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The National Oceanic and Atmospheric Administration is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere. NOAA warns of dangerous weather, charts seas and skies, guides the use and protection of ocean and coastal resources, and conducts research to improve understanding and stewardship of the environment. In addition to its civilian employees, 12,000 as of 2012, NOAA research and operations are supported by 300 uniformed service members who make up the NOAA Commissioned Officer Corps. The current Under Secretary of Commerce for Oceans and Atmosphere at the Department of Commerce and the agency's administrator is Kathryn D. Sullivan, who was nominated February 28, 2013, and confirmed March 6, 2014. Wikipedia.

Cziczo D.J.,Massachusetts Institute of Technology | Froyd K.D.,National Oceanic and Atmospheric Administration | Froyd K.D.,University of Colorado at Boulder
Atmospheric Research | Year: 2014

Cirrus are high altitude clouds composed of ice crystals. They are the first tropospheric clouds that can scatter incoming solar radiation and the last which can trap outgoing terrestrial heat. Considering their extensive global coverage, estimated at between 25 and 33% of the Earth's surface, cirrus exert a measurable climate forcing. The global radiative influence depends on a number of properties including their altitude, ice crystal size and number density, and vertical extent. These properties in turn depend on the ability of upper tropospheric aerosol particles to initiate ice formation. Because aerosol populations, and therefore cirrus formation mechanisms, may change due to human activities, the sign of cirrus forcing (a net warming or cooling) due to anthropogenic effects is not universally agreed upon although most modeling studies suggest a positive effect. Cirrus also play a major role in the water cycle in the tropopause region, affecting not only redistribution in the troposphere but also the abundance of vapor entering the stratosphere. Both the current lack of understanding of cirrus properties and the need to improve our ability to project changes due to human activities in the future highlight the critical need to determine the aerosol particles on which cirrus form.This review addresses what is currently known about the abundance, size and composition of cirrus-forming particles. We review aircraft-based field studies which have either collected cirrus ice residuals for off-line analysis or determined their size, composition and other properties in situ by capturing ice crystals and sublimating/removing the condensed phase water. This review is predominantly restricted to cirrus clouds. Limited comparisons are made to other ice-containing (e.g., mixed-phase) cloud types. The findings of recent reviews on laboratory measurements that mimic upper tropospheric cirrus formation are briefly summarized. The limitations of the current state of the art in cirrus ice residual studies are outlined. Important ancillary measurements and how they are integrated with ice residual data are also presented. Concluding statements focus on the need for specific instrumentation and future studies. © 2013 Elsevier B.V. Source

Haynie A.C.,National Oceanic and Atmospheric Administration
Fisheries Science | Year: 2014

An important element in the U.S. management of fisheries in the North Pacific is the existence of Community Development Quotas (CDQs) which grant community corporations the right to fish in many fisheries off the coast of Alaska. The eastern Bering Sea pollock fishery is the largest of these fisheries, with 10 % of the quota allocated to CDQs. The CDQ program evolved from a partial catch share program that existed from 1992 to 1999 within a limited-entry fishery to a full catch share program with separate spatial rights. In this paper I examine the temporal and spatial uses of CDQ rights and how these uses have changed since the implementation of catch shares throughout the fishery. I also discuss the dispersion of CDQ royalties since the program's inception and examine the prices of CDQ fishing rights from 1992 to 2005 when data on quota value were reported to the government. I compare quota prices to information about walleye pollock fishing and examine the evolving use of CDQ rights. The use of the CDQ right has changed from extending the season to enabling fishing in otherwise closed areas during the season. The number of vessels fishing with CDQ rights has declined substantially, with all pollock CDQ fishing now done by at-sea processors. © 2014 The Japanese Society of Fisheries Science. Source

Polkinghorne R.,University of Colorado at Boulder | Vukicevic T.,National Oceanic and Atmospheric Administration
Monthly Weather Review | Year: 2011

Assimilation of cloud-affected infrared radiances from the Geostationary Operational Environmental Satellite-8 (GOES-8) is performed using a four-dimensional variational data assimilation (4DVAR) system designated as the Regional Atmospheric Modeling Data Assimilation System (RAMDAS). A cloud mask is introduced in order to limit the assimilation to points that have the same type of cloud in the model and observations, increasing the linearity of the minimization problem. A series of experiments is performed to determine the sensitivity of the assimilation to factors such as the maximum-allowed residual in the assimilation, the magnitude of the background error decorrelation length for water variables, the length of the assimilation window, and the inclusion of other data such as ground-based data including data from the Atmospheric Emitted Radiance Interferometer (AERI), a microwave radiometer, radiosonde, and cloud radar. In addition, visible and near-infrared satellite data are included in a separate experiment. The assimilation results are validated using independent ground-based data. The introduction of the cloud mask where large residuals are allowed has the greatest positive impact on the assimilation. Extending the length of the assimilation window in conjunction with the use of the cloud mask results in a better-conditioned minimization, as well as a smoother response of the model state to the assimilation. © 2011 American Meteorological Society. Source

Lin Y.,State University of New York at Stony Brook | Lin Y.,University Corporation for Atmospheric Research | Lin Y.,National Oceanic and Atmospheric Administration | Colle B.A.,State University of New York at Stony Brook
Monthly Weather Review | Year: 2011

A new bulk microphysical parameterization (BMP) scheme is presented that includes a diagnosed riming intensity and its impact on ice characteristics. As a result, the new scheme represents a continuous spectrum from pristine ice particles to heavily rimed particles and graupel using one prognostic variable [precipitating ice (PI)] rather than two separate variables (snow and graupel). In contrast to most existing parameterization schemes that use fixed empirical relationships to describe ice particles, general formulations are proposed to consider the influences of riming intensity and temperature on the projected area, mass, and fall velocity of PI particles. The proposed formulations are able to cover the variations of empirical coefficients found in previous observational studies. The new scheme also reduces the number of parameterized microphysical processes by~50% as compared to conventional six-category BMPs and thus it is more computationally efficient. The new scheme (called SBU-YLIN) has been implemented in the Weather Research and Forecasting (WRF) model and compared with three other schemes for two events during the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE-2) over the central Oregon Cascades. The new scheme produces surface precipitation forecasts comparable to more complicated BMPs. The new scheme reduces the snow amounts aloft as compared to other WRF schemes and compares better with observations, especially for an event with moderate riming aloft. Sensitivity tests suggest both reduced snow depositional growth rate and more efficient fallout due to the contribution of riming to the reduction of ice water content aloft in the new scheme, with a larger impact from the partially rimed snow and fallout. © 2011 American Meteorological Society. Source

Cheung W.W.L.,University of British Columbia | Sarmiento J.L.,Princeton University | Dunne J.,National Oceanic and Atmospheric Administration | Frolicher T.L.,Princeton University | And 4 more authors.
Nature Climate Change | Year: 2013

Changes in temperature, oxygen content and other ocean biogeochemical properties directly affect the ecophysiology of marine water-breathing organisms1-3. Previous studies suggest that the most prominent biological responses are changes in distribution4-6, phenology 7-8 and productivity9. Both theory and empirical observations also support the hypothesis that warming and reduced oxygen will reduce body size of marine fishes10-12. However, the extent to which such changes would exacerbate the impacts of climate and ocean changes on global marine ecosystems remains unexplored. Here, we employ a model to examine the integrated biological responses of over 600 species of marine fishes due to changes in distribution, abundance and body size. The model has an explicit representation of ecophysiology, dispersal, distribution, and population dynamics3. We show that assemblage-averaged maximum body weight is expected to shrink by 14-24% globally from 2000 to 2050 under a high-emission scenario. About half of this shrinkage is due to change in distribution and abundance, the remainder to changes in physiology. The tropical and intermediate latitudinal areas will be heavily impacted, with an average reduction of more than 20%. Our results provide a new dimension to understanding the integrated impacts of climate change on marine ecosystems. Copyright © 2013 Macmillan Publishers Limited. Source

Rozas L.P.,National Oceanic and Atmospheric Administration | Minello T.J.,Galveston Laboratory
Estuaries and Coasts | Year: 2010

We examined the distribution of nekton across the marsh landscape using a 1-m2 drop sampler to compare nekton densities across three different salinity zones (intermediate, brackish, saline), three pond sizes (diameter <40 m= small, ~250-300 m=medium, >750 m=large), and two habitat types (pond, adjacent marsh) in the Barataria Bay Estuary, Louisiana. Nekton assemblages of ponds and the adjacent marsh appeared to be structured by the responses of individual species to the estuarine salinity gradient at the landscape scale and to pond habitat attributes locally. Our results indicate that ponds in the brackish and saline zones are more important nursery areas for most fishery species than ponds in the intermediate zone. Medium and large ponds supported higher densities of most species than small ponds. Most species of nekton were associated with vegetation structure, and individuals of these species were either concentrated among plant stems at the marsh edge or within submerged aquatic vegetation in ponds. © Coastal and Estuarine Research Federation 2010. Source

Akmaev R.A.,National Oceanic and Atmospheric Administration
Reviews of Geophysics | Year: 2011

At the turn of the century R. G. Roble advanced an ambitious program of developing an atmospheric general circulation model (GCM) extending from the surface to the exosphere. He outlined several areas of research and application to potentially benefit from what is now commonly called whole atmosphere modeling. The purpose of this article is to introduce this new field to a broader geophysical community and document its progress over the last decade. Vertically extended models are commonly built from existing weather and climate GCM codes incorporating a number of approximations, which may no longer be valid. Promising directions of further model development, potential applications, and challenges are outlined. One application is space weather or day-to-day and seasonal variability in the ionosphere and thermosphere driven by meteorological processes from below. Various modes of connection between the lower and upper atmosphere had been known before, but new and sometimes unexpected observational evidence has emerged over the last decade. Persistent "nonmigrating" wavy structures in plasma and neutral densities and a dramatic response of the equatorial ionosphere to sudden warmings in the polar winter stratosphere are just two examples. Because large-scale meteorological processes are predictable several days in advance, whole atmosphere weather prediction models open an opportunity for developing a real forecast capability for space weather. © 2011 by the American Geophysical Union. Source

Liu Y.,University of Wisconsin - Madison | Key J.R.,National Oceanic and Atmospheric Administration
Environmental Research Letters | Year: 2014

In September 2012, Arctic sea ice cover reached a record minimum for the satellite era. The following winter the sea ice quickly returned, carrying through to the summer when ice extent was 48% greater than the same time in 2012. Most of this rebound in the ice cover was in the Chukchi and Beaufort Seas, areas experiencing the greatest decline in sea ice over the last three decades. A variety of factors, including ice dynamics, oceanic and atmospheric heat transport, wind, and solar insolation anomalies, may have contributed to the rebound. Here we show that another factor, below-average Arctic cloud cover in January-February 2013, resulted in a more strongly negative surface radiation budget, cooling the surface and allowing for greater ice growth. More thick ice was observed in March 2013 relative to March 2012 in the western Arctic Ocean, and the areas of ice growth estimated from the negative cloud cover anomaly and advected from winter to summer with ice drift data, correspond well with the September ice concentration anomaly pattern. Therefore, decreased wintertime cloud cover appears to have played an important role in the return of the sea ice cover the following summer, providing a partial explanation for large year-to-year variations in an otherwise decreasing Arctic sea ice cover. © 2014 IOP Publishing Ltd. Source

Rykaczewski R.R.,Princeton University | Dunne J.P.,National Oceanic and Atmospheric Administration
Geophysical Research Letters | Year: 2010

A leading hypothesis relating productivity with climate variability in the California Current Ecosystem (CCE) describes an alternation between warmer, well-stratified periods of low productivity and cooler periods of high productivity. This empirical relationship suggests that productivity will decline with global warming. Here, we explore the response of productivity to future climate change in the CCE using an earth system model. This model projects increases in nitrate supply and productivity in the CCE during the 21st century despite increases in stratification and limited change in wind-driven upwelling. We attribute the increased nitrate supply to enrichment of deep source waters entering the CCE resulting from decreased ventilation of the North Pacific. Decreases in dissolved-oxygen concentration and increasing acidification accompany projected increases in nitrate. This analysis illustrates that anthropogenic climate change may be unlike past variability; empirical relationships based on historical observations may be inappropriate for projecting ecosystem responses to future climate change. © 2010 by the American Geophysical Union. Source

Mo K.C.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2010

Data from observations and the Intergovernmental Panel on Climate Change (IPCC) twentieth-century climate change model [phase 3 of the Coupled Model Intercomparison Project (CMIP3)] simulations were analyzed to examine the decadal changes of the impact of ENSO on air temperature Tair and precipitation P over the United States. The comparison of composites for the early period (1915-60) and the recent period (1962-2006) indicates that cooling (warming) over the south and warming (cooling) over the north during ENSO warm (cold) winters have been weakening. The ENSO influence on winter P over the Southwest is strengthening, while the impact on P over the Ohio Valley is weakening for the recent decades. These differences are not due to the long-term trends in Tair or P; they are attributed to the occurrence of the central Pacific (CPAC) ENSO events in the recent years. The CPAC ENSO differs from the canonical eastern Pacific (EPAC) ENSO. The EPAC ENSO has a sea surface temperature anomaly (SSTA) maximum in the eastern Pacific. Enhanced convection extends from the date line to the eastern Pacific, with negative anomalies in the western Pacific. The atmospheric responses resemble a tropical Northern Hemisphere pattern. The wave train is consistent with the north-south Tair contrast over North America during the EPAC ENSO winters. The CPAC ENSO has enhanced convection in the central Pacific. The atmospheric responses show a Pacific-North American pattern. It is consistent with west-east contrast in Tair and more rainfall over the Southwest during the CPAC ENSO winters. © 2010 American Meteorological Society. Source

Klotzbach P.J.,Colorado State University | Blake E.S.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2013

Both El Niño-Southern Oscillation (ENSO) and the Madden-Julian oscillation (MJO) have been documented in previous research to impact tropical cyclone (TC) activity around the globe. This study examines the relationship of each mode individually along with a combined index on tropical cyclone activity in the north-central Pacific. Approximately twice as many tropical cyclones form in the north-central Pacific in El Niño years compared with La Niña years. These differences are attributed to a variety of factors, including warmer sea surface temperatures, lower sea level pressures, increased midlevel moisture, and anomalous midlevel ascent in El Niño years. When the convectively enhanced phase of the MJO is located over the eastern and central tropical Pacific, the north-central Pacific tends to have more tropical cyclone activity, likely because of reduced vertical wind shear, lower sea level pressures, and increased vertical motion. The convectively enhanced phase of the MJO is also responsible for most of the TCs that undergo rapid intensification in the north-central Pacific. A combined MJO-ENSO index that is primarily associated with anomalous rising motion over the tropical eastern Pacific has an even stronger relationship with north-central Pacific TCs, as well as rapid intensification, than either individually. © 2013 American Meteorological Society. Source

Knopfmeier K.H.,University of Oklahoma | Stensrud D.J.,National Oceanic and Atmospheric Administration
Weather and Forecasting | Year: 2013

The expansion of surfacemesoscale networks (mesonets) across theUnited States provides a high-resolution observational dataset for meteorological analysis and prediction. To clarify the impact of mesonet data on the accuracy of surface analyses, 2-mtemperature, 2-m dewpoint, and 10-mwind analyses for 2-week periods during the warm and cold seasons produced through an ensemble Kalman filter (EnKF) approach are compared to surface analyses created by the Real-Time Mesoscale Analysis (RTMA). Results show in general a similarity between the EnKF analyses and the RTMA, with the EnKF exhibiting a smoother appearance with less smallscale variability.Root-mean-square (RMS) innovations are generally lower for temperature and dewpoint from the RTMA, implying a closer fit to the observations. Kinetic energy spectra computed from the two analyses reveal that the EnKF analysis spectra match more closely to the spectra computed from observations and numericalmodels in earlier studies.Data-denial experiments using theEnKF completed for the firstweek of the warm and cold seasons, as well as for two periods characterized by high mesoscale variability within the experimental domain, show that mesonet data removal imparts only minimal degradation to the analyses. This is because of the localized background covariances computed for the four surface variables having spatial scales much larger than the average spacing of mesonet stations. Results show that removing 75% of the mesonet observations has only minimal influence on the analysis. © 2013 American Meteorological Society. Source

Nicholls M.E.,University of Colorado at Boulder | Montgomery M.T.,Naval Postgraduate School, Monterey | Montgomery M.T.,National Oceanic and Atmospheric Administration
Atmospheric Chemistry and Physics | Year: 2013

Simulations are conducted with a cloud-resolving numerical model to examine the transformation of a weak incipient mid-level cyclonic vortex into a tropical cyclone. Results demonstrate that two distinct pathways are possible and that development along a particular pathway is sensitive to model physics and initial conditions. One pathway involves a steady increase of the surface winds to tropical cyclone strength as the radius of maximum winds gradually decreases. A notable feature of this evolution is the creation of small-scale lower tropospheric cyclonic vorticity anomalies by deep convective towers and subsequent merger and convergence by the low-level secondary circulation. The second pathway also begins with a strengthening low-level circulation, but eventually a significantly stronger mid-level circulation develops. Cyclogenesis occurs subsequently when a small-scale surface concentrated vortex forms abruptly near the center of the larger-scale circulation. The small-scale vortex is warm core throughout the troposphere and results in a fall in local surface pressure of a few millibars. It usually develops rapidly, undergoing a modest growth to form a small tropical cyclone. Many of the simulated systems approach or reach tropical cyclone strength prior to development of a prominent mid-level vortex so that the subsequent formation of a strong small-scale surface concentrated vortex in these cases could be considered intensification rather than genesis.

Experiments are performed to investigate the dependence on the inclusion of the ice phase, radiation, the size and strength of the incipient mid-level vortex, the amount of moisture present in the initial vortex, and the sea surface temperature. Notably, as the sea surface temperature is raised, the likelihood of development along the second pathway is increased. This appears to be related to an increased production of ice. The sensitivity of the pathway taken to model physics and initial conditions revealed by these experiments raise the possibility that the solution to this initial value problem is near a bifurcation point. Future improvements to model parameterizations and more accurate observations of the transformation of disturbances to tropical cyclones should clarify the conditions that favor a particular pathway when starting from a mid-level vortex. © 2013 Author(s). Source

Veenhuis B.A.,National Oceanic and Atmospheric Administration
Monthly Weather Review | Year: 2013

Ensemble forecasting systems often contain systematic biases and spread deficiencies that can be correctedby statistical postprocessing. This study presents an improvement to an ensemble statistical postprocessingtechnique, called ensemble kernel density model output statistics (EKDMOS). EKDMOS uses model outputstatistics (MOS) equations and spread-skill relationships to generate calibrated probabilistic forecasts. TheMOS equations are multiple linear regression equations developed by relating observations to ensemblemean-based predictors. The spread-skill relationships are one-term linear regression equations that predictthe expected accuracy of the ensemble mean given the ensemble spread. To generate an EKDMOS forecast,theMOSequations are applied to each ensemble member. Kernel density fitting is used to create a probabilitydensity function (PDF) from the ensemble MOS forecasts. The PDF spread is adjusted to match the spreadpredicted by the spread-skill relationship, producing a calibrated forecast. The improved EKDMOS techniquewas used to produce probabilistic 2-m temperature forecasts from the North American EnsembleForecast System (NAEFS) over the period 1 October 2007-31 March 2010. The results were compared withan earlier spread adjustment technique, as well as forecasts generated by rank sorting the bias-correctedensemble members. Compared to the other techniques, the new EKDMOS forecasts were more reliable, hada better calibrated spread-error relationship, and showed increased day-to-day spread variability. Source

Benedict J.J.,Colorado State University | Maloney E.D.,Colorado State University | Sobel A.H.,Lamont Doherty Earth Observatory | Frierson D.M.,University of Washington | Donner L.J.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2013

Tropical intraseasonal variability is examined in version 3 of the Geophysical FluidDynamics Laboratory Atmosphere Model (AM3). In contrast to its predecessorAM2, AM3 uses a new treatment of deep and shallow cumulus convection and mesoscale clouds. The AM3 cumulus parameterization is a massflux-based scheme but also, unlike that in AM2, incorporatessubgrid-scale vertical velocities; these play a key role in cumulus microphysical processes. The AM3 convection scheme allows multiphase water substance produced in deep cumuli to be transported directly into mesoscale clouds, which strongly influence large-scale moisture and radiation fields. The authors examine four AM3 simulations using a control model and three versions with different modifications to the deep convection scheme. In the control AM3, using a convective closure based on CAPE relaxation, both MJO and Kelvin waves are weak relative to those in observations. By modifying the convective closure and trigger assumptions to inhibit deep cumuli, AM3 produces reasonable intraseasonal variability but a degraded mean state. MJO-like disturbances in the modified AM3 propagate eastwardat roughly the observed speed in the Indian Ocean but up to 2 times the observed speed inthe west Pacific Ocean. Distinct differences in intraseasonal convective organization andpropagation exist among the modified AM3 versions. Differences in vertical diabatic heating profiles associated with the MJO are also found. The two AM3 versions with the strongest intraseasonal signals have a more prominent "bottom heavy" heating profile leading the disturbance center and "top heavy" heating profile following the disturbance. The more realistic heating structures are associated with an improved depiction of moisture convergence and intraseasonal convective organization in AM3. © 2013 American Meteorological Society. Source

Cordeira J.M.,Plymouth State University | Martin Ralph F.,National Oceanic and Atmospheric Administration | Moore B.J.,University of Colorado at Boulder
Monthly Weather Review | Year: 2013

This study investigates the evolution of two zonally elongated atmospheric rivers (ARs) that produced >200mm of rainfall over mountainous regions of Northern California in late October 2010. Synoptic-scale analysis and air parcel trajectory analysis indicate that the ARs developed within high-CAPE environments characterized by troposphere-deep ascent as water vapor was transported directly from western North Pacific tropical cyclones (TCs) toward the equatorward entrance region of an intensifying North Pacific jet stream (NPJ). The same ARs were subsequently maintained as water vapor was transported from extratropical and subtropical regions over the central and eastern North Pacific in an environment characterized by quasigeostrophic forcing for ascent and strong frontogenesis along the anticyclonic shear side of an intense and zonally extended NPJ. Although the ARs developed in conjunction with water vapor transported from regions near TCs and in the presence of troposphere-deep ascent, an atmospheric water vapor budget illustrates that decreases in integrated water vapor (IWV) via precipitation are largely offset by the horizontal aggregation of water vapor along the AR corridors via IWV flux convergence in the presence of frontogenesis. The frameworks used for investigations of predecessor rain events ahead of TCs and of interactions between recurving TCs and the NPJ are also utilized to illustrate many dynamically similar processes related to AR development and evolution. Similarities include the following: water vapor transport directly from a TC, troposphere-deep ascent in a high-CAPE environment beneath the equatorward entrance region of an intensifying upper-tropospheric jet streak, interactions between diabatic outflow and an upper-tropospheric jet streak, and strong frontogenesis. © 2013 American Meteorological Society. Source

Hoerling M.,National Oceanic and Atmospheric Administration | Eischeid J.,University of Colorado at Boulder | Perlwitz J.,University of Colorado at Boulder
Journal of Climate | Year: 2010

In this study, the nature and causes for observed regional precipitation trends during 1977-2006 are diagnosed. It is found that major features of regional trends in annual precipitation during 1977-2006 are consistent with an atmospheric response to observed sea surface temperature (SST) variability. This includes drying over the eastern Pacific Ocean that extends into western portions of the Americas related to a cooling of eastern Pacific SSTs, and broad increases in rainfall over the tropical Eastern Hemisphere, including a Sahelian rainfall recovery and increased wetness over the Indo-West Pacific related to North Atlantic and Indo-West Pacific ocean warming. It is further determined that these relationships between SST and rainfall change are generally not symptomatic of human-induced emissions of greenhouse gases (GHGs) and aerosols. The intensity of regional trends simulated in climate models using observed time variability in greenhouse gases, tropospheric sulfate aerosol, and solar and volcanic aerosol forcing are appreciably weaker than those observed and also weaker than those simulated in atmospheric models using only observed SST forcing. The pattern of rainfall trends occurring in response to such external radiative forcing also departs significantly from observations, especially a simulated increase in rainfall over the tropical Pacific and southeastern Australia that are opposite in sign to the actual drying in these areas. Additional experiments illustrate that the discrepancy between observed and GHG-forced rainfall changes during 1977-2006 results mostly from the differences between observed and externally forced SST trends. Only weak rainfall sensitivity is found to occur in response to the uniform distribution of SST warming that is induced byGHGand aerosol forcing, whereas the particular pattern of the observed SST change that includes an increased SST contrast between the east Pacific and the Indian Ocean, and strong regional warming of the North Atlantic Ocean, was a key driver of regional rainfall trends. The results of this attribution study on the causes for 1977-2006 regional rainfall changes are used to discuss prediction challenges including the likelihood that recent rainfall trends might persist. © 2010 American Meteorological Society. Source

Stensrud D.J.,National Oceanic and Atmospheric Administration | Gao J.,University of Oklahoma
Monthly Weather Review | Year: 2010

The assimilation of operational Doppler radar observations into convection-resolving numerical weather prediction models for very short-range forecasting represents a significant scientific and technological challenge. Numerical experiments over the past few years indicate that convective-scale forecasts are sensitive to the details of the data assimilation methodology, the quality of the radar data, the parameterized microphysics, and the storm environment. In this study, the importance of horizontal environmental variability to very short-range (0-1 h) convective-scale ensemble forecasts initialized using Doppler radar observations is investigated for the 4-5 May 2007 Greensburg, Kansas, tornadic thunderstorm event. Radar observations of reflectivity and radial velocity from the operational Doppler radar network at 0230 UTC 5 May 2007, during the time of the first large tornado, are assimilated into each ensemble member using a three-dimensional variational data assimilation system (3DVAR) developed at the Center for Analysis and Prediction of Storms (CAPS). Very short-range forecasts are made using the nonhydrostatic Advanced Regional Prediction System (ARPS) model from each ensemble member and the results are compared with the observations. Explicit three-dimensional environmental variability information is provided to the convective-scale ensemble using analyses from a 30-km mesoscale ensemble data assimilation system. Comparisons between convective-scale ensembles with initial conditions produced by 3DVAR using 1) background fields that are horizontally homogeneous but vertically inhomogeneous (i.e., have different vertical environmental profiles) and 2) background fields that are horizontally and vertically inhomogeneous are undertaken. Results show that the ensemble with horizontally and vertically inhomogeneous background fields provides improved predictions of thunderstorm structure, mesocyclone track, and low-level circulation track than the ensemble with horizontally homogeneous background fields. This suggests that knowledge of horizontal environmental variability is important to successful convective-scale ensemble predictions and needs to be included in real-data experiments. © 2010 American Meteorological Society. Source

Leech P.J.,Georgia Institute of Technology | Lynch-Stieglitz J.,Georgia Institute of Technology | Zhang R.,National Oceanic and Atmospheric Administration
Earth and Planetary Science Letters | Year: 2013

Paleoclimate proxy evidence suggests a southward shift of the Intertropical Convergence Zone (ITCZ) during times of Northern Hemisphere cooling, including the Last Glacial Maximum, 19-23. ka before present. However, evidence for movement over the Pacific has mainly been limited to precipitation reconstructions near the continents, and the position of the Pacific marine ITCZ is less well constrained. In this study, we address this problem by taking advantage of the fact that the upper ocean density structure reflects the overlying wind field. We reconstruct changes in the upper ocean density structure during the LGM using oxygen isotope measurements on the planktonic foraminifera G. ruber and G. tumida in a transect of sediment cores from the Western Tropical Pacific. The data suggests a ridge in the thermocline just north of the present-day ITCZ persists for at least part of the LGM, and a structure in the Southern Hemisphere that differs from today. The reconstructed structure is consistent with that produced in a General Circulation Model with both a Northern and Southern Hemisphere ITCZ. © 2012 Elsevier B.V. Source

Rogers R.,National Oceanic and Atmospheric Administration
Journal of the Atmospheric Sciences | Year: 2010

The role of convective-scale processes in a 1.67-km mesoscale model simulation of the rapid intensification (RI) of Hurricane Dennis (2005) is presented. The structure and evolution of inner-core precipitating areas during RI, the statistical properties of precipitation during times experiencing vigorous convection (termed convective bursts here) and how they differ from nonburst times, possible differences in convective bursts associated with RI and those not associated with RI, and the impacts of precipitation morphology on the vortex-scale structure and evolution during RI are all examined. The onset of RI is linked to an increase in the areal extent of convective precipitation in the inner core, while the inner-core stratiform precipitating area remains unchanged and the intensity increases only after RI has begun. RI is not tied to a dramatic increase in the number of convective bursts nor in the characteristics of the bursts, such as burst intensity. Rather, the immediate cause of RI is a significant increase in updraft mass flux, particularly in the lowest 1.5 km. This increase in updraft mass flux is accomplished primarily by updrafts on the order of 1-2 m s -1, representing the bulk of the vertical motion distribution. However, a period of enhanced updraft mass flux in the midlevels by moderate to strong (>5 m s -1) updrafts located inside the radius of maximum winds occurs ~6 h prior to RI, indicating a synergistic relationship between convective bursts and the background secondary circulation prior to RI. This result supports the assertion that both buoyantly driven updrafts and slantwise near-neutral ascent are important features in eyewall structure, evolution, and intensification, including RI. © 2010 American Meteorological Society. Source

Shribak M.,National Oceanic and Atmospheric Administration
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2013

We describe a quantitative orientation-independent differential interference contrast (DIC) microscope, which allows bias retardation to be modulated and shear directions to be switched rapidly without any mechanical movement. The shear direction is switched by a regular liquid-crystal cell sandwiched between two standard DIC prisms. Another liquid-crystal cell modulates the bias. Techniques for measuring parameters of DIC prisms and calibrating the bias are shown. Two sets of raw DIC images with the orthogonal shear directions are captured within 1 s. Then the quantitative image of optical path gradient distribution within a thin optical section is computed. The gradient data are used to obtain a quantitative distribution of the optical path, which represents the refractive index gradient or height distribution. Computing enhanced regular DIC images with any desired shear direction is also possible. © 2013 Optical Society of America. Source

DiNezio P.N.,University of Hawaii at Manoa | Vecchi G.A.,National Oceanic and Atmospheric Administration | Clement A.C.,University of Miami
Journal of Climate | Year: 2013

Changes in the gradients in sea level pressure (SLP) and sea surface temperature (SST) along the equatorial Pacific are analyzed in observations and 101 numerical experiments performed with 37 climate models participating in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). The ensemble of numerical experiments simulates changes in the earth's climate during the 2004-1870 period in response to changes in natural (solar variations and volcanoes) and anthropogenic (well-mixed greenhouse gases, ozone, direct aerosol forcing, and land use) radiative forcings. A reduction in the zonal SLP gradient is present in observational records and is the typical response of the ensemble, yet only 26 out of the 101 experiments exhibit a reduced SLP gradient within 95% statistical confidence of the observed value. The multimodel response indicates a reduction of the Walker circulation to historical forcings, albeit an order of magnitude smaller than the observed value. There are multiple nonexclusive interpretations of these results: (i) the observed trend may not be entirely forced and includes a substantial component from internal variability; (ii) there are problems with the observational record that lead to a spuriously large trend; and (iii) the strength of theWalker circulation, as measured by the zonal SLP gradient, may be less sensitive to external forcing in models than in the real climate system. Analysis of a subset of experiments suggests that greenhouse gases act to weaken the circulation, but aerosol forcing drives a strengthening of the circulation, which appears to be overestimated by the models, resulting in a muted response to the combined anthropogenic forcings. © 2013 American Meteorological Society. Source

Craig J.K.,National Oceanic and Atmospheric Administration | Bosman S.H.,Florida State University
Estuaries and Coasts | Year: 2013

Seasonal hypoxia [dissolved oxygen (DO) ≤ 2 mg l-1] occurs over large regions of the northwestern Gulf of Mexico continental shelf during the summer months (June-August) as a result of nutrient enrichment from the Mississippi-Atchafalaya River system. We characterized the community structure of mobile fishes and invertebrates (i. e., nekton) in and around the hypoxic zone using 3 years of bottom trawl and hydrographic data. Species richness and total abundance were lowest in anoxic waters (DO ≤ 1 mg l-1) and increased at intermediate DO levels (2-4 mg l-1). Species were primarily structured as a benthic assemblage dominated by Atlantic croaker (Micropogonias undulatus) and sand and silver seatrout (Cynoscion spp.), and a pelagic assemblage dominated by Atlantic bumper (Chloroscombrus chrysurus). Of the environmental variables examined, bottom DO and distance to the edge of the hypoxic zone were most strongly correlated with assemblage structure, while temperature and depth were important in some years. Hypoxia altered the spatial distribution of both assemblages, but these effects were more severe for the benthic assemblage than for the pelagic assemblage. Brown shrimp, the primary target of the commercial shrimp trawl fishery during the summer, occurred in both assemblages, but was more abundant within the benthic assemblage. Given the similarity of the demersal nekton community described here to that taken as bycatch in the shrimp fishery, our results suggest that hypoxia-induced changes in spatial dynamics have the potential to influence harvest and bycatch interactions in and around the Gulf hypoxic zone. © 2012 Coastal and Estuarine Research Federation (outside the USA). Source

Wang H.-J.,CAS Institute of Atmospheric Physics | Yang S.,National Oceanic and Atmospheric Administration
Meteorologische Zeitschrift | Year: 2012

In this paper, studies on extreme climate in China including extreme temperature and precipitation, dust weather activity, tropical cyclone activity, intense snowfall and cold surge activity, floods, and droughts are reviewed based on the peer-reviewed publications in recent decades. The review is focused first on the climatological features, variability, and trends in the past half century and then on simulations and projections based on global and regional climate models. As the annual mean surface air temperature (SAT) increased throughout China, heat wave intensity and frequency overall increased in the past half century, with a large rate after the 1980s. The daily or yearly minimum SAT increased more significantly than the mean or maximum SAT. The long-term change in precipitation is predominantly characterized by the so-called southern flood and northern drought pattern in eastern China and by the overall increase over Northwest China. The interdecadal variation of monsoon, represented by the monsoon weakening in the end of 1970s, is largely responsible for this change in mean precipitation. Precipitation-related extreme events (e.g., heavy rainfall and intense snowfall) have become more frequent and intense generally over China in the recent years, with large spatial features. Dust weather activity, however, has become less frequent over northern China in the recent years, as result of weakened cold surge activity, reinforced precipitation, and improved vegetation condition. State-of-the-art climate models are capable of reproducing some features of the mean climate and extreme climate events. However, discrepancies among models in simulating and projecting the mean and extreme climate are also demonstrated by many recent studies. Regional models with higher resolutions often perform better than global models. To predict and project climate variations and extremes, many new approaches and schemes based on dynamical models, statistical methods, or their combinations have been developed, resulting in improved skills. With the improvements of climate model capability and resolution as well as our understanding of regional climate variability and extremes, these new approaches and techniques are expected to further improve the prediction and projection on regional climate variability and extremes over China in the future. © 2012 Gebrüder Borntraeger, Stuttgart. Source

Johnson G.C.,National Oceanic and Atmospheric Administration | Chambers D.P.,University of South Florida
Journal of Geophysical Research: Oceans | Year: 2013

Ocean mass variations are important for diagnosing sea level budgets, the hydrological cycle, the global energy budget, and ocean circulation variability. Here seasonal cycles and decadal trends of ocean mass from January 2003 to December 2012, both global and regional, are analyzed using GRACE Release-05 data. The trend of global flux of mass into the ocean approaches 2 cm decade-1 in equivalent sea level rise. Regional trends are of similar magnitude, with the North Pacific, South Atlantic, and South Indian oceans generally gaining mass and other regions losing mass. These trends suggest a spin-down of the North Pacific western boundary current extension and the Antarctic Circumpolar Current in the South Atlantic and South Indian oceans. The global average seasonal cycle of ocean mass is about 1 cm in amplitude, with a maximum in early October and volume fluxes in and out of the ocean reaching 0.5 Sv (1 Sv = 1 × 106 m3 s-1) when integrated over the area analyzed here. Regional patterns of seasonal ocean mass change have typical amplitudes of 1-4 cm, and include maxima in the subtropics and minima in the subpolar regions in hemispheric winters. The subtropical mass gains and subpolar mass losses in the winter spin-up both subtropical and subpolar gyres, hence the western boundary current extensions. Seasonal variations in these currents are order 10 Sv, but since the associated depth-averaged current variations are only order 0.1 cm s-1, they would be difficult to detect using in situ oceanographic instruments. © 2013. American Geophysical Union. All Rights Reserved. Source

Kessler W.S.,National Oceanic and Atmospheric Administration | Cravatte S.,Ird Institute Of Recherche Pour Le Developpement | Cravatte S.,Toulouse University Midi-Pyrenees
Journal of Geophysical Research: Oceans | Year: 2013

The mean absolute geostrophic circulation of the Coral Sea is constructed from climatological hydrographic data referenced to a 1000 m velocity field derived from Argo float drift. Two branches of the South Equatorial Current (SEC) enter the Coral Sea between New Caledonia and the Solomon Islands: the broad, upper thermocline North Vanuatu Jet (NVJ), and the narrow North Caledonian Jet (NCJ) extending to at least 1500 m. Most of this incoming flow leaves to the Solomon Sea. Four distinct pathways through the Coral Sea are traced by their water properties: (1) The NCJ crosses the Sea to the coast of Australia and turns north at densities sigma 25-27.4 as the main source of the Gulf of Papua (GPC) western boundary current, eventually feeding the New Guinea Coastal Undercurrent; (2) part of the shallow NVJ turns into the Solomon Sea in midbasin, carrying high-salinity water above sigma 25.5; (3) another part of the NVJ continues to Australia, then turns north to join the GPC, extending it to the surface; (4) a shallow finger of NVJ water, traced by low oxygen above sigma 25, turns south along the coast, beginning the East Australian Current (EAC) at 15°S. Total transport from the Coral to the Tasman Sea is small and shallow; instead, most of the EAC is fed from south of New Caledonia, consistent with the Island Rule. However, large transport fractions occur in narrow jets close to coastlines and reefs and are not well sampled, precluding a quantitative estimate of meridional redistribution of the incoming SEC. Key Points Argo float drift references Coral Sea climatological geostrophic currents Interior and boundary current transports largely explained by the Island Rule Three distinct pathways carry the SEC through the Coral Sea to the equator © 2013 The Authors. Source

Ward-Paige C.A.,Dalhousie University | Ward-Paige C.A.,National Oceanic and Atmospheric Administration | Lotze H.K.,Dalhousie University
PLoS ONE | Year: 2011

Background: Around the world, researchers are using the observations and experiences of citizens to describe patterns in animal populations. This data is often collected via ongoing sampling or by synthesizing past experiences. Since elasmobranchs are relatively rare, obtaining data for broad-scale trend analysis requires high sampling effort. Elasmobranchs are also relatively large and conspicuous and therefore it may be possible to enlist recreational divers to collect data on their occurrence and relative abundance from daily dive activities. For this, however, a good understanding of the value of data collected by recreational divers is essential. Methodology/Principal Findings: Here, we explore the value of recreational divers for censusing elasmobranchs using a diverse set of data sources. First, we use a simulation experiment to explore detection rates of the roving diver technique, used by recreational divers, across a range of fish densities and speeds. Next, using a field survey, we show that inexperienced recreational divers detect and count elasmobranchs as well as experienced recreational divers. Finally, we use semi-structured interviews of recreational dive instructors to demonstrate the value of their recollections in terms of effort and their descriptions of spatial and temporal distributions of sharks in Thailand. Conclusions/Significance: Overall, this study provides initial ground-work for using recreational divers for monitoring elasmobranch populations. If used appropriately, citizen-collected data may provide additional information that can be used to complement more standardized surveys and to describe population trends across a range of spatial and temporal scales. Due to the non-extractive nature of this data, recreational divers may also provide important insight into the success of conservation initiatives, such as shark sanctuaries and no-take zones. © 2011 Ward-Paige, Lotze. Source

Capotondi A.,University of Colorado at Boulder | Capotondi A.,National Oceanic and Atmospheric Administration
Journal of Geophysical Research: Oceans | Year: 2013

In this study we examine ENSO diversity in a 500 year control simulation of the National Center for Atmospheric Research (NCAR) Community Climate System Model version 4 (CCSM4), focusing on warm events. Standard and modified Niño3 and Niño4 indices are used to identify different event types. CCSM4 shows a rich diversity of El Niño flavors with characteristics that are comparable to what was found in observations, the SODA 2.0.2/3 ocean reanalysis, and the GFDL CM2.1 model, a climate model whose ENSO characteristics have been extensively analyzed. In agreement with previous studies available in the literature, warm events peaking in the central/western Pacific are characterized by wind stress and precipitation fields confined to the western side of the basin, and show weak or absent recharge/discharge thermocline processes. A heat budget analysis of four different El Niño flavors, peaking at different longitudes, confirms the leading role of the thermocline and zonal advective feedbacks in the Niño3 and Niño4 regions, respectively. However, the growth of events centered further west appears to be controlled by nonlinear zonal advection, a result that differs from what was found in the GFDL CM2.1 model, but that is consistent with some observational evidence. Key Points CCSM4 has different El Nino types Different dynamical processes control different types Most results are consistent with previous studies ©2013. American Geophysical Union. All Rights Reserved. Source

Waples R.S.,National Oceanic and Atmospheric Administration | Waples R.K.,Casa Azul
Molecular Ecology Resources | Year: 2011

An important use of genetic parentage analysis is the ability to directly calculate the number of offspring produced by each parent (ki) and hence effective population size, Ne. But what if parental genotypes are not available? In theory, given enough markers, it should be possible to reconstruct parental genotypes based entirely on a sample of progeny, and if so the vector of parental ki values. However, this would provide information only about parents that actually contributed offspring to the sample. How would ignoring the 'null' parents (those that produced no offspring) affect an estimate of Ne? The surprising answer is that null parents have no effect at all. We show that: (i) The standard formula for inbreeding Ne can be rewritten so that it is a function only of sample size and ; it is not necessary to know the total number of parents (N). This same relationship does not hold for variance Ne. (ii) This novel formula provides an unbiased estimate of Ne even if only a subset of progeny is available, provided the parental contributions are accurately determined, in which case precision is also high compared to other single-sample estimators of Ne. (iii) It is not necessary to actually reconstruct parental genotypes; from a matrix of pairwise relationships (as can be estimated by some current software programs), it is possible to construct the vector of ki values and estimate Ne. The new method based on parentage analysis without parents (PwoP) can potentially be useful as a single-sample estimator of contemporary Ne, provided that either (i) relationships can be accurately determined, or (ii) can be estimated directly. © 2011 Blackwell Publishing Ltd. Source

Fiore A.M.,National Oceanic and Atmospheric Administration | Levy Ii H.,University of Washington | Jaffe D.A.,University of Washington
Atmospheric Chemistry and Physics | Year: 2011

Changing land-use and climate may alter emissions of biogenic isoprene, a key ozone (O3) precursor. Isoprene is also a precursor to peroxy acetyl nitrate (PAN) and thus affects partitioning among oxidized nitrogen (NOy) species, shifting the balance towards PAN, which more efficiently contributes to long-range transport relative to nitric acid (HNO3) which rapidly deposits. With a suite of sensitivity simulations in the MOZART-2 global tropospheric chemistry model, we gauge the relative importance of the intercontinental influence of a 20% increase in North American (NA) isoprene and a 20% decrease in NA anthropogenic emissions (nitrogen oxides (NOx), non-methane volatile organic compounds (NMVOC) and NOx + NMVOC + carbon monoxide + aerosols). The surface O3 response to NA isoprene emissions (ΔO3-ISOP) in surface air over NA is about one third of the response to all NA anthropogenic emissions (ΔO 3-ANTH; although with different signs). Over intercontinental distances, ΔO3-ISOP is relatively larger; in summer and fall, ΔO3-ISOP in surface air over Europe and North Africa (EU region) is more than half of ΔO3-ANTH. Future increases in NA isoprene emissions could thus offset decreases in EU surface O 3 resulting from controls on NA anthropogenic emissions. Over the EU region, ΔPAN-ISOP at 700 hPa is roughly the same magnitude as ΔPAN-ANTH (oppositely signed). Outside of the continental source region, the percentage changes in PAN are at least twice as large as for surface O3, implying that long-term PAN measurements at high altitude sites may help to detect O3 precursor emission changes. We find that neither the baseline level of isoprene emissions nor the fate of isoprene nitrates contributes to the large diversity in model estimates of the anthropogenic emission influence on intercontinental surface O3 or oxidized nitrogen deposition reported in the recent TF HTAP multi-model studies (TFHTAP, 2007). © 2011 Author(s). Source

Pothoven S.A.,National Oceanic and Atmospheric Administration | Fahnenstiel G.L.,Michigan Technological University
Journal of Great Lakes Research | Year: 2013

Six offshore stations in southeastern Lake Michigan were sampled during a pre quagga mussel Dreissena rostriformis bugensis period (1995-2000) and a post quagga mussel period (2007-2011). Chlorophyll a fluorescence profiles were used to characterize chlorophyll a concentrations during early (June-July) and late (August-September) summer stratification. During the early summer period the average whole water column chlorophyll a, the deep chlorophyll maximum, and the size of deep chlorophyll layer decreased 50%, 55%, and 92%, respectively, between 1995-2000 and 2007-2011. By contrast, in late summer there were no changes in these metrics between periods. Surface mixed layer chlorophyll a in early and late summer did not differ between time periods. On the other hand, chlorophyll a in the near bottom zone (bottom 20. m) declined 63% and 54% between 1995-2000 and 2007-2011 in early and late summer respectively. Changes in total phosphorus between 1995-2000 and 2007-2011 were less dramatic, with declines of 22-27% in early summer and 11-30% in late summer. Changes in the chlorophyll a conditions were attributed to dreissenid mussels which reduced material available from the spring bloom and disrupted the horizontal transport of nutrients to the offshore. Although light availability increased (i.e., increased secchi depths), reduced nutrient availability and spring diatom abundance resulted in a much smaller deep chlorophyll layer in 2007-2011. © 2013. Source

Xu Q.,National Oceanic and Atmospheric Administration
Journal of the Atmospheric Sciences | Year: 2010

Modal and nonmodal growths of nonhydrostatic symmetric perturbations in an unbounded domain are examined in comparison with their hydrostatic counterparts. It is shown that themodal growth rate is a function of a single internal parameter s, the slope of the cross-band wave pattern. The maximum nonmodal growth of total perturbation energy norm is produced, also as a function of s, by an optimal combination of one geostrophic neutral mode and two paired nongeostrophic growing and decaying (or propagating) modes in the unstable (or stable) region. The hydrostatic approximation inflates the maximum modal growth rate significantly (or boundlessly) as the basic-state Richardson number Ri is small (or→0) and inflates the maximum nonmodal growth rate significantly (or boundlessly) as |s| is large (or → ∞). Inside the unstable region, the maximum nonmodal growth scaled by the modal growth is a bounded increasing function of growth time τ but reduces to 1 at (Ri, s) = (1/4, -2) where the three modes become orthogonal to each other. Outside the unstable region, themaximumnonmodal growth is a periodic function of τ and the maximum growth time τm is bounded between 1/4 and 1/2 of the period of the paired propagating modes. The scaled maximum nonmodal growth reaches the global maximum at s=-Ri-1 ± Ri-1(1 - Ri)1/2 (themarginal-stability boundary) for any τ if Ri≤1, or at s=-1±(1-Ri-1)1/2 for τ =τm if Ri>1.When the neutralmode is filtered, the nonmodal growth becomes nongeostrophic and smaller than its counterpart growth constructed by the three modes but still significantly larger than the modal growth in general. The scaled maximum nongeostrophic nonmodal growth reaches the global maximum at s=-Ri-1 ± Ri-1(1 - Ri)1/2 for any τ if Ri ≤ 1, or at s 5 =Ri-1/2 for τ = τm if Ri > 1. Normalized inner products between the modes are introduced to measure their nonorthogonality and interpret their constructed nonmodal growths physically. Source

Stensrud D.J.,National Oceanic and Atmospheric Administration
Journal of the Atmospheric Sciences | Year: 2013

The ability of deep monsoon convection to influence the larger-scale circulation over North America is investigatedfor a 6-day-long case study during the 2006 North American monsoon. Results from Rossby wave ray tracing and numerical simulations using the Advanced Research Weather Research and Forecasting model indicate that North American monsoon convection provides a source region for stationary Rossby waves. Two wave trains are seen in the numerical model simulations,with behaviors that agree well with expectations from theory and ray tracing. The shorter and faster-moving wave train moves eastward from the source region in Mexico and reaches the western Atlantic within 4 days. The longer and slower-moving wave train travels northeastward and reaches the coastal New England region within 6 days. An upstream tail of anticyclonic vorticity extends westward from the source region into the central Pacific Ocean. The monsoon convection appearsto help cut off the low-level anticyclonic flow by developing low-level southerly flow in the Gulf of Mexico and northerly flow in the eastern Pacific, as suggested in earlier global model studies. However, the stationary Rossby wave trainsfurther alter the location and intensity of deep convection in locations remote from the monsoon. These results suggest that unless a numerical model can correctly predict monsoon convection, the ability of the model to produce accurate forecasts of the large-scale pattern and associated convective activity beyond a few days is in question. This result may be important for global climate modeling, since an inaccurate prediction of monsoon convection would lead to an inaccurate Rossby wave response. © 2013 American Meteorological Society. Source

Joyce T.M.,Woods Hole Oceanographic Institution | Zhang R.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2010

The Atlantic meridional overturning circulation (AMOC) simulated in various ocean-only and coupled atmosphere-ocean numerical models often varies in time because of either forced or internal variability. The path of the Gulf Stream (GS) is one diagnostic variable that seems to be sensitive to the amplitude of the AMOC, yet previous modeling studies show a diametrically opposed relationship between the two variables. In this note this issue is revisited, bringing together ocean observations and comparisons with the GFDL Climate Model version 2.1 (CM2.1), both of which suggest a more southerly (northerly) GS path when the AMOCis relatively strong (weak). Also shown are some examples of possible diagnostics to compare various models and observations on the relationship between shifts in GS path and changes in AMOC strength in future studies. © 2010 American Meteorological Society. Source

Lamarque J.-F.,U.S. National Center for Atmospheric Research | Solomon S.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2010

The primary focus of this paper is the analysis of the roles of long-term increases in carbon dioxide (CO2) and sea surface temperatures (used as indicators of climate change) and man-made halocarbons (indicators of chemical ozone depletion linked to halogens) in explaining the observed trend of ozone in the tropical lower stratosphere and implications for related variables including temperature and tropopause height. Published estimates indicate a decrease of approximately 10% in observed ozone concentrations in this region between 1979 and 2005. Using a coupled chemistry-climate atmosphere model forced by observed sea surface temperatures and surface concentrations of long-lived greenhouse gases and halocarbons, the authors show that the simulations display substantial decreases in tropical ozone that compare well in both latitudinal and vertical structure with those observed. Based on sensitivity simulations, the analysis indicates that the decreases in the lower stratospheric (85-50 hPa) tropical ozone distribution are mostly associated with increases in CO2 and sea surface temperatures, in contrast to those at higher latitudes, which are largely driven by halocarbon increases. Factors influencing temperature trends and tropopause heights in this region are also probed. It is shown that the modeled temperature trends in the lower tropical stratosphere are also associated with increases in CO2 and sea surface temperatures. Following the analysis of lower stratospheric tropical temperature trends, the secondary focus of this paper is on related changes in tropopause height. Much of the simulated tropopause rise in the tropical zone as measured by tropopause height is found to be linked to increases in sea surface temperatures and CO2, while increases in halocarbons dominate the tropopause height changes in the subtropics near 30°; both drivers thus affect different regions of the simulated changes in the position of the tropopause. Finally, it is shown that halocarbon increases dominate the changes in the width of the region where modeled total ozone displays tropical character (as indicated by low values of the column abundance). Hence the findings suggest that climate changes and halocarbon changes make different contributions to different metrics used to characterize tropical change. © 2010 American Meteorological Society. Source

Tanhua T.,Leibniz Institute of Marine Science | Waugh D.W.,Johns Hopkins University | Bullister J.L.,National Oceanic and Atmospheric Administration
Geophysical Research Letters | Year: 2013

Transient tracer measurements can constrain the rates and pathways of ocean ventilation and act as proxies for biogeochemically relevant gases such as CO2 and oxygen. Various techniques have deduced changes in ocean ventilation over decadal timescales using transient tracer measurements made on repeat sections, but these require a priori assumptions about mixing in the ocean interior. Here, we introduce a simple, direct observational method that takes advantage of the similar atmospheric increase rates of chlorofluorocarbon-12 and sulfur hexafluoride, but with a time lag (offset) of 14-15 years. Such repeat measurements can be directly compared without prior assumptions about mixing. A difference larger than ∼2 years between modern sulfur hexafluoride and historical chlorofluorocarbon-12 tracer ages implies a change in ventilation, although lack of difference does not necessarily imply no change. Several tracer data sets are presented, which suggest changes in ventilation in the South Pacific and North Atlantic Oceans. © 2013. American Geophysical Union. All Rights Reserved. Source

Aberson S.D.,National Oceanic and Atmospheric Administration
Monthly Weather Review | Year: 2010

In 1997, the National Hurricane Center and the Hurricane Research Division began operational synoptic surveillance missions with the Gulfstream IV-SP jet aircraft to improve the numerical guidance for hurricanes that threaten the continental United States, Puerto Rico, the U.S. Virgin Islands, and Hawaii. During the first 10 yr, 176 such missions were conducted. Global Positioning System dropwindsondes were released from the aircraft at 150-200-km intervals along the flight track in the environment of each tropical cyclone to obtain wind, temperature, and humidity profiles from flight level (about 150 hPa) to the surface. The observations were processed and formatted aboard the aircraft and sent to the National Centers for Environmental Prediction and the Global Telecommunications System to be ingested into the Global Forecast System, which serves as initial and boundary conditions for regional numerical models that also forecast tropical cyclone track and intensity. The results of an observing system experiment using these data are presented. © 2010 American Meteorological Society. Source

Riemer M.,Naval Postgraduate School, Monterey | Montgomery M.T.,Naval Postgraduate School, Monterey | Montgomery M.T.,National Oceanic and Atmospheric Administration | Nicholls M.E.,University of Colorado at Boulder
Atmospheric Chemistry and Physics | Year: 2010

An important roadblock to improved intensity forecasts for tropical cyclones (TCs) is our incomplete understanding of the interaction of a TC with the environmental flow. In this paper we re-visit the canonical problem of a TC in vertical wind shear on an f-plane. A suite of numerical experiments is performed with intense TCs in moderate to strong vertical shear. We employ a set of simplified model physics ĝ€" a simple bulk aerodynamic boundary layer scheme and "warm rain" microphysics ĝ€" to foster better understanding of the dynamics and thermodynamics that govern the modification of TC intensity. In all experiments the TC is resilient to shear but significant differences in the intensity evolution occur.

The ventilation of the TC core with dry environmental air at mid-levels and the dilution of the upper-level warm core are two prevailing hypotheses for the adverse effect of vertical shear on storm intensity. Here we propose an alternative and arguably more effective mechanism how cooler and drier (lower θe) air ĝ€" "anti-fuel" for the TC power machine ĝ€" can enter the core region of the TC. Strong and persistent, shear-induced downdrafts flux low θe air into the boundary layer from above, significantly depressing the θe values in the storm's inflow layer. Air with lower θe values enters the eyewall updrafts, considerably reducing eyewall θ e values in the azimuthal mean. When viewed from the perspective of an idealised Carnot-cycle heat engine a decrease of storm intensity can thus be expected. Although the Carnot cycle model is ĝ€" if at all ĝ€" only valid for stationary and axisymmetric TCs, a close association of the downward transport of low θe into the boundary layer and the intensity evolution offers further evidence in support of our hypothesis.

The downdrafts that flush the boundary layer with low θe air are tied to a quasi-stationary, azimuthal wave number 1 convective asymmetry outside of the eyewall. This convective asymmetry and the associated downdraft pattern extends outwards to approximately 150 km. Downdrafts occur on the vortex scale and form when precipitation falls out from sloping updrafts and evaporates in the unsaturated air below. It is argued that, to zero order, the formation of the convective asymmetry is forced by frictional convergence associated with the azimuthal wave number 1 vortex Rossby wave structure of the outer-vortex tilt. This work points to an important connection between the thermodynamic impact in the near-core boundary layer and the asymmetric balanced dynamics governing the TC vortex evolution. Source

Lee S.-K.,University of Miami | Wang C.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2010

A simple dynamic model is proposed to illustrate the multidecadal oscillation of the Atlantic Ocean thermohaline circulation. The proposed oscillation relies on alternating actions of positive and negative feedbacks, which are operated by a slow adjustment of the ocean circulation and the associated time delay in the advective flux response to a change in meridional density gradient. The key element of the oscillation is the time delay, which is conceptually related to the basin-crossing time of long Rossby waves in the highlatitude North Atlantic. For a sufficiently long time delay, the solution becomes unstable in some regions of model parameter space and oscillates with a period of approximately 2 times the delay time. © 2010 American Meteorological Society. Source

Fogarty M.J.,National Oceanic and Atmospheric Administration
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2014

The perception that ecosystem-based fishery management is too complex and poorly defined remains a primary impediment to its broadscale adoption and implementation. Here, I attempt to offer potential solutions to these concerns. Specifically, I focus on pathways that can contribute to overall simplification by moving toward integrated place-based management plans and away from large numbers of species-based plans; by using multispecies or ecosystem models and indicators that permit the simultaneous and consistent assessment of ecosystem components while also incorporating broader environmental factors; and by consolidating individual administrative and regulatory functions now mostly dealt with on a species-by-species basis into a more integrated framework for system-wide decision-making. The approach focuses on emergent properties at the community and ecosystem levels and seeks to identify simpler modeling and analysis tools for evaluation. Adoption of ecosystem-based management procedures relying on simple decision rules and metrics is advocated. It is recommended that we replace static concepts for individual species focusing on maximum sustainable yield with a dynamic ecosystem yield framework that involves setting system-wide reference points along with constraints to protect individual species, habitats, and nontarget organisms in a dynamic environmental setting. Source

Emile-Geay J.,University of Southern California | Cobb K.M.,Georgia Institute of Technology | Mann M.E.,Pennsylvania State University | Wittenberg A.T.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2013

Reducing the uncertainties surrounding the impacts of anthropogenic climate change requires vetting general circulation models (GCMs) against long records of past natural climate variability. This is particularly challenging in the tropical Pacific Ocean, where short, sparse instrumental data preclude GCM validation on multidecadal to centennial time scales. This two-part paper demonstrates the application of two statistical methodologies to a network of accurately dated tropical climate records to reconstruct sea surface temperature (SST) variability in the Niño-3.4 region over the past millennium. While Part I described the methods and established their validity and limitations, this paper presents several reconstructions of Niño-3.4, analyzes their sensitivity to procedural choices and input data, and compares them to climate forcing time series and previously published tropical Pacific SST reconstructions. The reconstructions herein show remarkably similar behavior at decadal to multidecadal scales, but diverge markedly on centennial scales. The amplitude of centennial variability in each reconstruction scales with the magnitude of the A.D. 1860-1995 trend in the target dataset's Niño-3.4 index, with Extended Reconstructed SST, version 3 (ERSSTv3)>the Second Hadley Centre SST dataset (HadSST2)> Kaplan SST; these discrepancies constitute a major source of uncertainty in reconstructing preinstrumental Niño-3.4 SST. Despite inevitable variance losses, the reconstructed multidecadal variability exceeds that simulated by a state-of-the-art GCM (forced and unforced) over the past millennium, while reconstructed centennial variability is incompatible with constant boundary conditions. Wavelet coherence analysis reveals a robust antiphasing between solar forcing and Niño-3.4 SST on bicentennial time scales, but not on shorter time scales. Implications for GCM representations of the tropical Pacific climate response to radiative forcing are then discussed.© 2013 American Meteorological Society. Source

Kessler W.S.,National Oceanic and Atmospheric Administration | Cravatte S.,Institute Of Recherche Pour Le Developpement
Journal of Physical Oceanography | Year: 2013

Historical section data extending to 1985 are used to estimate the interannual variability of transport entering the Coral Sea between New Caledonia and the Solomon Islands. Typical magnitudes of this variability are ±5-8 Sv (Sv = 106 m3 s-1) in the 0-400-m layer relative to 400 m, and ±8-12 Sv in the 0-2000-m layer relative to 2000 m, on a mean of close to 230 Sv (relative to 2000 m). Transport increases a few months after an El Nin~o event and decreases following a La Niña. Interannual transport variability is well simulated by a reduced-gravity long Rossby wave model. Vigorous westward-propagating mesoscale eddies can yield substantial aliasing on individual ship or glider surveys. Since transport variability is surface intensified and well correlated with satellite-derived surface geostrophic currents, a simple index of South Equatorial Current transport based on satellite altimetry is developed. © 2013 American Meteorological Society. Source

Johnson D.S.,National Oceanic and Atmospheric Administration | Short M.I.,Brown University
Estuaries and Coasts | Year: 2013

In summer 2009, the effects of 6 years of landscape-level experimental nutrient enrichment on the eastern mudsnail, Nassarius obsoletus (formerly Ilyanassa obsoleta), were examined. The experiment was conducted in five tidal creeks (two nutrient-enriched, three reference creeks) in the Plum Island Estuary, Massachusetts, USA. (42°44′ N, 70°52′ W). After 6 years of enrichment, N. obsoletus size structure differed between treatment creeks with adult snails on average 14 % larger in enriched creeks. N. obsoletus densities (in individuals per square meter) and biomass (in grams dry weight per square meter) were four times higher in nutrient-enriched versus reference creeks. Nutrient enrichment did not significantly affect the biomass of benthic microalgae (a N. obsoletus food resource), but snail density was significantly correlated with benthic microalgal biomass, suggesting bottom-up control of snails. N. obsoletus is abundant on the east and west coast of North America; thus, N. obsoletus density and biomass may be useful variables for monitoring eutrophication effects on North American estuaries. © 2012 Coastal and Estuarine Research Federation. Source

Ming Y.,Stanford University | Ramaswamy V.,Stanford University | Persad G.,Stanford University | Persad G.,National Oceanic and Atmospheric Administration
Geophysical Research Letters | Year: 2010

Absorbing aerosols affect global-mean precipitation primarily in two ways. They give rise to stronger shortwave atmospheric heating, which acts to suppress precipitation. Depending on the top-of-the-atmosphere radiative flux change, they can also warm up the surface with a tendency to increase precipitation. Here, we present a theoretical framework that takes into account both effects, and apply it to analyze the hydrological responses to increased black carbon burden simulated with a general circulation model. It is found that the damping effect of atmospheric heating can outweigh the enhancing effect of surface warming, resulting in a net decrease in precipitation. The implications for moist convection and general circulation are discussed. © 2010 by the American Geophysical Union. Source

Lupton J.,National Oceanic and Atmospheric Administration | Evans L.,Oregon State University
Geophysical Research Letters | Year: 2013

We have compared the helium isotope ratio in five samples of Pacific marine air spanning the 40 year period between 1973 and 2013 against a secondary gas standard. In a separate experiment we directly compared the 3He/ 4He ratio in air samples collected in 1973 and 2013 at the same location in La Jolla, California, eliminating any geographical bias. Both experiments are consistent with zero time rate of change for atmospheric 3He/4He. Our best estimate for the rate of change of the 3He/4He ratio in Pacific marine air is -0.0014 ± 0.0045%/yr (2σ), indicating that air helium is still a valid standard for terrestrial helium isotope measurements. Key Points Air helium isotope ratio has not changed significantly Study covers air helium variations over last 40 years Air helium is a viable standard for helium isotope measurements ©2013. American Geophysical Union. All Rights Reserved. Source

Soden B.J.,University of Miami | Vecchi G.A.,National Oceanic and Atmospheric Administration
Geophysical Research Letters | Year: 2011

We assess the vertical distribution of cloud feedbacks in coupled climate models, taking care to distinguish between cloud feedbacks and a change in cloud forcing. We show that the effect of cloud changes on the longwave fluxes provides a strong positive feedback that is broadly consistent across models. In contrast, the effect of cloud changes on the shortwave fluxes ranges from a modest negative to a strong positive feedback, and is responsible for most of the intermodel spread in net cloud feedback. The feedback from high clouds is positive in all models, and is consistent with that anticipated by the Proportionately Higher Anvil Temperature hypothesis over the tropics. In contrast, low cloud cover is responsible for roughly three-quarters of the difference in global mean net cloud feedback among models, with the largest contributions from regions associated with low-level subtropical marine cloud systems. Copyright 2011 by the American Geophysical Union. Source

Irisov V.,Zel Technologies, LLC | Voronovich A.,National Oceanic and Atmospheric Administration
Journal of Physical Oceanography | Year: 2011

The wave breaking events in a continuous spectrum of surface gravity waves are investigated numerically in 2D within a framework of the potential motion model. It is claimed that the major physical mechanism leading to wave breaking is "squeezing" of relatively short waves by the surface currents due to longer waves (the "concertina" effect), which causes the shorter waves to steepen and become unstable. It is demonstrated that locations of the breaking events are well correlated with the maximumof local current convergence, although slightly worse correlation of the locations with the local steepness of undulating surface cannot reliably exclude the latter mechanism either. It is found also that the breaking events are very rare for random surfaces with a root-mean-square (RMS) current gradient below a threshold value of about 1 s-1. The process of wave breaking was investigated by two numerical codes. One of them is based on approximation of continuous media with a discrete Hamiltonian system, which can be integrated in time very efficiently and accurately but is limited to single-valued profiles. The other is the Laplacian approach, which can explicitly exhibit the overturning of plunging breakers. Study of the discrete system shows that wave breaking is associated with the explosive growth of a certain spatially localized mode of the system. © 2011 American Meteorological Society. Source

Yuan Y.,National Climate Center | Yang S.,National Oceanic and Atmospheric Administration | Zhang Z.,National Climate Center
Journal of Climate | Year: 2012

The authors examine different evolution features of the low-level anticyclone over the tropical northwestern Pacific between eastern Pacific (EP) El Niño events and central Pacific (CP) El Niño events. During EP El Niño, the low-level anticyclone shows an eastward movement from the northern Indian Ocean to the east of the Philippines. During CP El Niño, however, the anticyclone is mostly confined to the west of the Philippines. It is weaker, exhibits a shorter lifetime, and lacks eastward movement compared to the Philippine Sea anticyclone (PSAC) during EP El Niño. Investigation into the possible impact of Indian Ocean (IO) sea surface temperature (SST) on the evolution of the low-level anticyclone during EP and CP El Niño indicates that both SST and low-level atmospheric circulation over the IO are related more strongly with EP El Niño than with CP El Niño. The IO SST tends to exert a more prominent influence on PSAC during EP El Niño than during CP El Niño. During the developing summer and autumn of EP El Niño, the anomalous anticyclone over the northern Indian Ocean excited by positive IO dipole may contribute to an early development of the PSAC. During the winter and decaying spring, the anomalous anticyclone to the east of the Philippines instigated by the IO basin-wide warming mode also favors a larger persistence of the PSAC. During CP El Niño, however, IO SST shows a negligible impact on the evolution of the anticyclone. © 2012 American Meteorological Society. Source

Juang H.H.,National Oceanic and Atmospheric Administration | Hong S.-Y.,Yonsei University
Monthly Weather Review | Year: 2010

A semi-Lagrangian advection scheme is developed for falling hydrometeors in hopes of replacing the conventional Eulerian scheme that has been widely used in the cloud microphysics scheme of numerical atmospheric models. This semi-Lagrangian scheme uses a forward advection method to determine the advection path with or without iteration, and advected mass in a two-time-level algorithm with mass conservation. Monotonicity is considered in mass-conserving interpolation between Lagrangian grids and model Eulerian grids, thus making it a positive definite advection scheme. For mass-conserving interpolation between the two grid systems, the piecewise constant method (PCM), piecewise linear method (PLM), and piecewise parabolic method (PPM) are proposed. The falling velocity at the bottom cell edge is modified to avoid unphysical deformation by scanning from the top layer to the bottom of the model, which enables the use of a large time step with reasonable accuracy. The scheme is implemented and tested in the Weather Research and Forecasting (WRF) Single-Moment 3-Class Microphysics Scheme (WSM3). In a theoretical test bed with constant terminal velocity, the proposed semi-Lagrangian algorithm shows that the higher-order interpolation scheme produces less diffusive features at maximal precipitation. Results from another idealized test bed with mass-weighted terminal velocity demonstrate that the accuracy of the proposed scheme is still satisfactory even with a time step of 120 s when the mean terminal velocity averaged at the departure and arrival points is employed. A two-dimensional (2D) squall-line test using the WSM3 scheme shows that the control run with the Eulerian advection scheme and the semi-Lagrangian run with the PCM method reveal similar results, whereas behaviors using the PLM and PPM are similar with higherresolution features, such as mammatus-like clouds. © 2010 American Meteorological Society. Source

Seo K.-H.,Pusan National University | Wang W.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2010

This study investigates the capability for simulating the Madden-Julian oscillation (MJO) in a series of atmosphere-ocean coupled and uncoupled simulations using NCEP operational general circulation models. The effect of air-sea coupling on the MJO is examined by comparing long-term simulations from the coupled Climate Forecast System (CFS T62) and the atmospheric Global Forecast System (GFS T62) models. Another coupled simulation with a higher horizontal resolution model (CFS T126) is performed to investigate the impact of model horizontal resolution. Furthermore, to examine the impact on a deep convection scheme, an additional coupled T126 run (CFS T126RAS) is conducted with the relaxed Arakawa-Schubert (RAS) scheme. The most important factors for the proper simulation of the MJO are investigated from these runs. The empirical orthogonal function, lagged regression, and spectral analyses indicated that the interactive air-sea coupling greatly improved the coherence between convection, circulation, and other surface fields on the intraseasonal time scale. A higher horizontal resolution run (CFS T126) did not show significant improvements in the intensity and structure. However, GFS T62, CFS T62, and CFS T126 all yielded the 30-60-day variances that were not statistically distinguishable from the background red noise spectrum. Their eastward propagation was stalled over the Maritime Continent and far western Pacific. In contrast to the model simulations using the simplified Arakawa-Schubert (SAS) cumulus scheme, CFS T126RAS produced statistically significant spectral peaks in the MJO frequency band, and greatly improved the strength of the MJO convection and circulation. Most importantly, the ability of MJO convection signal to penetrate into the Maritime Continent and western Pacific was demonstrated. In this simulation, an early-stage shallow heating and moistening preconditioned the atmosphere for subsequent intense MJO convection and a top-heavy vertical heating profile was formed by stratiform heating in the upper and middle troposphere, working to increase temperature anomalies and hence eddy available potential energy that sustains the MJO. The stratiform heating arose from convective detrainment of moisture to the environment and stratiform anvil clouds. Therefore, the following factors were analyzed to be most important for the proper simulation of the MJO rather than the correct simulations of basic-state precipitation, sea surface temperature, intertropical convergence zone, vertical zonal wind shear, and lower-level zonal winds: 1) an elevated vertical heating structure (by stratiform heating), 2) a moisture-stratiform instability process (a positive feedback process between moisture and convective-stratiform clouds), and 3) the low-level moisture convergence to the east of MJO convection (through the appropriate moisture and convective-stratiform cloud processes-circulation interactions). The improved MJO simulation did improve the global circulation response to the tropical heating and may extend the predictability of weather and climate over Asia and North America. © 2010 American Meteorological Society. Source

Wang K.,Beijing Normal University | Augustine J.,National Oceanic and Atmospheric Administration | Dickinson R.E.,University of Texas at Austin
Journal of Geophysical Research: Atmospheres | Year: 2012

Surface incident solar radiation (Rs) drives weather and climate changes. Observations of Rs have been widely used as reference data to evaluate climate model simulations and satellite retrievals. However, few have studied uncertainties of Rs observations, especially long term. This paper compares Rs from 1995 to 2011 at collocated sites collected by the Surface Radiation Budget Network (SURFRAD), the U.S. Climate Reference Network (USCRN) and the AmeriFlux network. SURFRAD stations have measured separately the diffuse and direct components of Rs as well as Rs by a pyranometer, while Rs was measured by a pyranometer or a net radiometer at the USCRN and AmeriFlux sites. Rs can be calculated by summing the diffuse and direction radiation measurements. Rs measured by the summation technique was compared those measured by a pyranometer or a net radiometer at collocated sites. Agreement among these four independent Rs measurements is good with correlation coefficients higher than 0.98 and an average error (one standard deviation) of about 4% at both hourly and monthly time scales. Rs has a large spatial variability at the hourly time scale, even exceeding 100Wm-2 in ∼6km. This spatial variability is substantially reduced at the monthly time scale. The two independent measurement systems at the SURFRAD sites agree rather well in annual variability of Rs with an average relative standard deviation error of 34%. The errors are 71% and 85% for the USCRN and AmeriFlux sites. Evidently, caution should be taken when using the Rs data collected at the USCRN and AmeriFlux sites to study annual variability of Rs. © 2012. American Geophysical Union. All Rights Reserved. Source

Asaf D.,Weizmann Institute of Science | Rotenberg E.,Weizmann Institute of Science | Tatarinov F.,Weizmann Institute of Science | Dicken U.,Weizmann Institute of Science | And 2 more authors.
Nature Geoscience | Year: 2013

Limited understanding of carbon dioxide sinks and sources on land is often linked to the inability to distinguish between the carbon dioxide taken up by photosynthesis, and that released by respiration1,2. Carbonyl sulphide, a sulphur-containing analogue of carbon dioxide, is also taken up by plants, and could potentially serve as a powerful proxy for photosynthetic carbon dioxide uptake, which cannot be directly measured above the leaf scale. Indeed, variations in atmospheric concentrations of carbonyl sulphide are closely related to those of carbon dioxide at regional, local and leaf scales3-9. Here, we use eddy covariance and laser spectroscopy 10 to estimate the net exchange of carbon dioxide and carbonyl sulphide across three pine forests, a cotton field and a wheat field in Israel. We estimate gross primary productivity-a measure of ecosystem photosynthesis-directly from the carbonyl sulphide fluxes, and indirectly from carbon dioxide fluxes. The two estimates agree within an error of ±15%. The ratio of carbonyl sulphide to carbon dioxide flux at the ecosystem scale was consistent with the variability in mixing ratios observed on seasonal timescales in the background atmosphere. We suggest that atmospheric measurements of carbonyl sulphide flux could provide an independent constraint on estimates of gross primary productivity, key to projecting the response of the land biosphere to climate change. Copyright © 2013 Macmillan Publishers Limited. Source

Fang Y.,Princeton University | Fang Y.,Carnegie Institution for Science | Naik V.,UCAR Geophysical Fluid Dynamics Laboratory | Horowitz L.W.,National Oceanic and Atmospheric Administration | Mauzerall D.L.,Princeton University
Atmospheric Chemistry and Physics | Year: 2013

Increases in surface ozone (O3) and fine particulate matter (≤2.5 μm aerodynamic diameter, PM2.5) are associated with excess premature human mortalities. We estimate changes in surface O3 and PM2.5 from pre-industrial (1860) to present (2000) and the global present-day (2000) premature human mortalities associated with these changes. We extend previous work to differentiate the contribution of changes in three factors: emissions of short-lived air pollutants, climate change, and increased methane (CH4) concentrations, to air pollution levels and associated premature mortalities. We use a coupled chemistry-climate model in conjunction with global population distributions in 2000 to estimate exposure attributable to concentration changes since 1860 from each factor. Attributable mortalities are estimated using health impact functions of long-term relative risk estimates for O3 and PM2.5 from the epidemiology literature. We find global mean surface PM2.5 and health-relevant O3 (defined as the maximum 6-month mean of 1-h daily maximum O 3 in a year) have increased by 8 ± 0.16 μg m-3 and 30 ± 0.16 ppbv (results reported as annual average ±standard deviation of 10-yr model simulations), respectively, over this industrial period as a result of combined changes in emissions of air pollutants (EMIS), climate (CLIM) and CH4 concentrations (TCH4). EMIS, CLIM and TCH4 cause global population-weighted average PM2.5 (O3) to change by +7.5 ± 0.19 μg m-3 (+25 ± 0.30 ppbv), +0.4 ± 0.17 μg m-3 (+0.5 ± 0.28 ppbv), and 0.04 ± 0.24 μg m-3 (+4.3 ± 0.33 ppbv), respectively. Total global changes in PM2.5 are associated with 1.5 (95% confidence interval, CI, 1.2-1.8) million cardiopulmonary mortalities and 95 (95% CI, 44-144) thousand lung cancer mortalities annually and changes in O3 are associated with 375 (95% CI, 129-592) thousand respiratory mortalities annually. Most air pollution mortality is driven by changes in emissions of short-lived air pollutants and their precursors (95% and 85% of mortalities from PM2.5 and O3 respectively). However, changing climate and increasing CH4 concentrations also contribute to premature mortality associated with air pollution globally (by up to 5% and 15%, respectively). In some regions, the contribution of climate change and increased CH4 together are responsible for more than 20% of the respiratory mortality associated with O3 exposure. We find the interaction between climate change and atmospheric chemistry has influenced atmospheric composition and human mortality associated with industrial air pollution. Our study highlights the benefits to air quality and human health of CH4 mitigation as a component of future air pollution control policy. © 2013 Author(s). Source

Byron C.J.,University of New England at Biddeford | Burke B.J.,National Oceanic and Atmospheric Administration
Reviews in Fish Biology and Fisheries | Year: 2014

Many species of salmon around the world migrate to open ocean environments for multiple years and then return to their natal rivers to spawn. How exactly salmon are able to execute these long distance migrations, and the impact of environmental conditions on migration behavior, is not well understood. Individual based modeling is one tool that has been used to explore salmon migration in the ocean. Although models are usually not able to confirm whether a particular behavior is used, they can rule out some behaviors as unrealistic. An extensive review of published literature suggests that there is no universal migration behavior. Behaviors that fish use to navigate depend on where they are in the ocean relative to where they are going, as well as the ocean flows and conditions along the way. Future models of salmon migration should be flexible and at an appropriate scale to capture variable oceanographic conditions and fish responses. © 2014 Springer International Publishing Switzerland. Source

Overland J.E.,National Oceanic and Atmospheric Administration | Wang M.,University of Washington
Geophysical Research Letters | Year: 2013

The observed rapid loss of thick multiyear sea ice over the last 7 years and the September 2012 Arctic sea ice extent reduction of 49% relative to the 1979-2000 climatology are inconsistent with projections of a nearly sea ice-free summer Arctic from model estimates of 2070 and beyond made just a few years ago. Three recent approaches to predictions in the scientific literature are as follows: (1) extrapolation of sea ice volume data, (2) assuming several more rapid loss events such as 2007 and 2012, and (3) climate model projections. Time horizons for a nearly sea ice-free summer for these three approaches are roughly 2020 or earlier, 2030 ± 10 years, and 2040 or later. Loss estimates from models are based on a subset of the most rapid ensemble members. It is not possible to clearly choose one approach over another as this depends on the relative weights given to data versus models. Observations and citations support the conclusion that most global climate model results in the CMIP5 archive are too conservative in their sea ice projections. Recent data and expert opinion should be considered in addition to model results to advance the very likely timing for future sea ice loss to the first half of the 21st century, with a possibility of major loss within a decade or two. © 2013 American Geophysical Union. All Rights Reserved. Source

Melet A.,Princeton University | Hallberg R.,National Oceanic and Atmospheric Administration | Legg S.,Princeton University | Polzin K.,Woods Hole Oceanographic Institution
Journal of Physical Oceanography | Year: 2013

The ocean interior stratification and meridional overturning circulation are largelysustained by diapycnal mixing. The breaking of internal tides is a major source of diapycnal mixing. Many recent climate models parameterize internal-tide breaking using the scheme of St. Laurent et al. While this parameterization dynamically accounts for internal-tide generation, the vertical distribution of the resultant mixing is ad hoc, prescribing energy dissipation to decay exponentially above the ocean bottomwith a fixed-length scale.Recently, Polzin formulated a dynamically based parameterization, in which the vertical profile of dissipation decays algebraically with a varying decay scale, accounting for variable stratification using Wentzel-Kramers-Brillouin (WKB) stretching. This study compares two simulations using the St. Laurent and Polzin formulations in the Climate Model, version 2G (CM2G), ocean-ice-atmosphere coupled model, with the same formulation for internal-tide energy input. Focusing mainly on the Pacific Ocean, where the deep low-frequency variability is relatively small, the authors show that the ocean state shows modest but robust and significant sensitivity to the vertical profile of internal-tide-driven mixing.Therefore, not only the energy input to the internal tides matters, but also where in thevertical it is dissipated. © 2013 American Meteorological Society. Source

Johnson D.S.,National Oceanic and Atmospheric Administration
Journal of Crustacean Biology | Year: 2014

A northern range extension is presented here for the marsh fiddler crab Uca pugnax (Smith, 1870). In summer 2014, adult crabs were found as far north as Hampton, New Hampshire (42°5527N, 70°4913W), which is 80 km north of its previously established northern limit determined in 2003. Thus, the mean annual northern movement of U. pugnax is currently 7.2 km year-1. I hypothesize that crabs recruited to the most northern sites during 2012 or 2013 when ocean temperatures were up to 1.3°C higher than the average of the previous decade. In a scenario of continued warming oceans associated with climate change, the range of U. pugnax is thus predicted to continue to extend northward. Given that fiddler crabs are ecosystem engineers affecting coastal wetland productivity, biogeochemistry and sediment structure, the introduction of this species into northern salt marshes may have consequences for marsh structure and function.. © Copyright 2014 by The Crustacean Society. Published by Brill NV, Leiden. Source

Wu B.,Chinese Academy of Meteorological Sciences | Overland J.E.,National Oceanic and Atmospheric Administration | D'arrigo R.,Lamont Doherty Earth Observatory
Tellus, Series A: Dynamic Meteorology and Oceanography | Year: 2012

We used monthly mean surface wind data from the National Centers for Environmental Prediction/National Centers for Atmospheric Research (NCEP/NCAR) reanalysis dataset during the period 1979-2010 to describe the first two patterns of Arctic surface wind variability by means of the complex vector empirical orthogonal function (CVEOF) analysis. The first two patterns respectively account for 31 and 16% of its total anomalous kinetic energy. The leading pattern consists of the two subpatterns: the northern Laptev Sea (NLS) pattern and the Arctic dipole (AD) pattern. The second pattern contains the northern Kara Sea (NKS) pattern and the central Arctic (CA) pattern. Over the past two decades, the combined dynamical forcing of the first two patterns has contributed to Arctic September sea ice extent (SIE) minima and its declining trend. September SIE minima are mainly associated with the negative phase of the AD pattern and the positive phase of the CA pattern during the summer (July to September) season, and both phases coherently show an anomalous anticyclone over the Arctic Ocean. Wind patterns affect September SIE through their frequency and intensity. The negative trend in September SIE over the past two decades is associated with increased frequency and enhanced intensity of the CA pattern during the melting season from April to September. Thus, it cannot be simply attributed to the AD anomaly characterised by the second empirical orthogonal function mode of sea level pressure north of 70 N. The CA pattern exhibited interdecadal variability in the late 1990s, and an anomalous cyclone prevailed before 1997 and was then replaced by an anomalous anticyclone over the Arctic Ocean that is consistent with the rapid decline trend in September SIE. This paper provides an alternative way to identify the dominant patterns of climate variability and investigate their associated Arctic sea ice variability from a dynamical perspective. Indeed, this study investigates only the role of surface wind dynamical forcing in resulting September SIE minima and trend in terms of CVEOF, without even considering contributions from other factors. © 2012 B. Wu et al. Source

Holland D.S.,National Oceanic and Atmospheric Administration | Herrera G.E.,Bowdoin College
Ecological Economics | Year: 2012

Failure to manage the harvest of a metapopulation at its underlying ecological scale can lead to extirpation of discrete subpopulations and reduce productivity. However, it may be difficult and costly to assess and manage stocks at a finer spatial scale, and there is generally greater uncertainty about the size of substocks than about the aggregate stock. We use a two-patch, age-structured metapopulation model to compare the performance of global vs. area-specific total allowable catch constraints (TACs). The relative performance of these approaches, in terms of profits and risk of depleting subpopulations, depends upon biological, technical and economic parameters - in particular various kinds of uncertainty, aggregation of fish stocks, and the spatial dynamics of different age classes. Surprisingly, a global TAC is less risky when there is little mixing of the subpopulations, as long as target mortality rates are not set too high. The advantage of the global TAC is reduced when there is mixing and migration between the subpopulations, particularly when these dynamics are asymmetric. However, a regulator naïve to the nature of the true spatial dynamics (and hence the spatially optimal target fishing mortality rates) may still be better off employing a global TAC. © 2012 . Source

Pfeiffer L.,National Oceanic and Atmospheric Administration | Lin C.-Y.C.,University of California at Davis
Journal of Environmental Economics and Management | Year: 2012

We investigate the behavior of farmers who share an underground aquifer. In the case where seepage may occur the resource is nonexclusive, giving rise to a spatial externality whereby pumping by one user affects others nearby. Theoretically, these externalities are potentially important causes of welfare loss. Using a unique spatial data set of groundwater users in western Kansas, we are able to empirically measure the physical and behavioral effects of groundwater pumping by neighbors. To address the simultaneity of neighbors' pumping, we use the neighbors' permitted water allocation as an instrument for their pumping. We estimate that 2.5% of the total groundwater extracted each year in western Kansas is over-extraction due to the effects of spatial externalities. Individuals who own multiple wells internalize their own externality by trading off pumping at one well for pumping at another. © 2012 Elsevier Inc.. Source

Reyes-Tomassini J.,National Oceanic and Atmospheric Administration
Fish Physiology and Biochemistry | Year: 2013

The manner in which behavior influences the gonadotropin-releasing hormone (GnRH) axis in hermaphroditic fishes is not understood. The Gilthead seabream, Sparus aurata, is a protandrous hermaphrodite with a complex gonadal cycle consisting of a quiescent, pre-spawning, spawning, and post-spawning stage. On two separate experiments, I used real-time quantitative PCR to measure the mRNA expression of three GnRH isoforms in homogenized seabream whole-brain extracts. In the first experiment, I measured the levels of GnRH-1, GnRH-2, and GnRH-3 mRNA throughout the gonad cycle. All three GnRH mRNAs increase around the peak of the spawning season (December). GnRH-3 mRNA expression is also elevated in August, which coincides with the beginning of gonad differentiation. All three GnRH mRNAs have the lowest expression levels in the month of September. There was no difference between males and females in the expression levels of any of the three GnRH mRNA. In the second experiment, I measured individual dominance ranks in six groups of fish, three during quiescence and three during spawning. GnRH-1 mRNA expression was positively correlated with dominance rank only during the quiescent period. The more dominant fish tended to have higher GnRH-1 mRNA expression. The existence of a quiescent-only correlation between GnRH-1 mRNA and dominance rank suggests a mechanism by which activation of gonad maturation could occur first in the most dominant ambisexual fish. © 2012 Springer Science+Business Media Dordrecht (outside the USA). Source

Churnside J.H.,Earth System Research Laboratory | Marchbanks R.D.,National Oceanic and Atmospheric Administration
Geophysical Research Letters | Year: 2015

The first synoptic measurements of subsurface plankton layers were made in the western Arctic Ocean in July 2014 using airborne lidar. Layers were detected in open water and in pack ice where up to 90% of the surface was covered by ice. Layers under the ice were less prevalent, weaker, and shallower than those in open water. Layers were more prevalent in the Chukchi Sea than in the Beaufort Sea. Three quarters of the layers observed were thinner than 5 m. The presence of these layers, which are not adequately captured in satellite data, will influence primary productivity, secondary productivity, fisheries recruitment, and carbon export to the benthos. © 2015. American Geophysical Union. All Rights Reserved. Source

Squires D.,National Oceanic and Atmospheric Administration
Journal of Environmental Economics and Management | Year: 2016

The theory of virtual quantities, the dual to virtual prices, provides a framework to analyze competitive multiproduct firm behavior under multiple quantity controls on inputs and outputs, including command-and-control quotas and transferable property rights. The framework addresses the firm[U+05F3]s reactions to regulatory controls, impacts of adding or dropping quantity controls, inferring unrationed from rationed production, and conversion from command-and-control quotas to cap-and-trade systems with transferable property rights and secondary market behavior. The paper develops reasons for failure of quasi-concavity of technology, extends the elasticity of intensity[U+05F3]s properties, and integrates the virtual price and virtual quantity frameworks. Virtual quantities are applied to assess potential firm responses to quantity controls and a potential transferable property right in a Malaysian fishery. © 2015. Source

The North Atlantic right whale (Eubalaena glacialis) is a critically endangered large whale species found in waters off the U.S. and Canadian Atlantic coasts. The primary human-caused threats are entanglement in fishing gear and collisions with vessels. Since 2002, NOAA's National Marine Fisheries Service has implemented both seasonally and dynamically managed protective zones where right whales occur to reduce these threats; Seasonal Area Management (SAM) and Dynamic Area Management (DAM) for the reduction of right whale entanglements with fishing gear, and Seasonal Management Areas (SMA) and Dynamic Management Areas (DMA) for reduction of vessel collisions. This paper analyzes the presence of frequent concentrations of right whales outside of SAM and SMA zones, represented by the spatial and temporal occurrence of DAMs and DMAs. A grid of 1 min×1 min squares was geospatially applied to locations of DAMs and DMAs from April 2002 through June 2011 and the number of management areas that intersected each 1 min square was populated. DAMs and DMAs were most highly concentrated along the central Gulf of Maine. Of the 131 DAMs and DMAs implemented, 97 (74.0%) intersected this area, and were primarily implemented from October through February. The results of this analysis will aid in consideration of possible modifications to the size and location of SMAs along the northern Atlantic coast of the U.S. and other management actions for the reduction of vessel collisions with right whales. © 2012. Source

Murphy D.M.,National Oceanic and Atmospheric Administration
Aerosol Science and Technology | Year: 2016

In free molecular flow the slower speed of heavier molecules means that they spend more time in the ion source of a mass spectrometer. Hence the sensitivity of the thermal desorption mass spectrometers such as the Aerodyne Aerosol Mass Spectrometer (AMS) should include a term that scales as the square root of the molecular weight. Thermal decomposition on the vaporizer reduces the molecular weight prior to ionization and changes electron impact cross-sections. Thermal decomposition therefore has the potential to change the sensitivity, in some cases by more than a factor of three. Current AMS calibrations that rely upon an ammonium nitrate calibration and scaling for other components with a relative ionization efficiency may overestimate the concentration of large, thermally stable molecules and underestimate small or thermally unstable molecules. The overall sensitivity of the AMS to organics includes a partial cancellation of these effects. There is an incomplete understanding of the vaporization process, including that of ammonium nitrate. © 2016 American Association for Aerosol Research. Source

Miller T.J.,National Oceanic and Atmospheric Administration
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2013

Selectivity and catch comparison studies are important for surveys that use two or more gears to collect relative abundance information. Prevailing model-based analytical methods for studies using a paired-gear design assume a binomial model for the data from each pair of gear sets. Important generalizations include nonparametric smooth size effects and normal random pair and size effects, but current methods for fitting models that account for random smooth size effects are restrictive, and observations within pairs may exhibit extra-binomial variation. I propose a hierarchical model that accounts for random smooth size effects among pairs and extra-binomial variation within pairs with a conditional beta-binomial distribution. I compared relative performance of models with different conditional distribution and random effects assumptions fit to data on 16 species from an experiment carried out in the US Northwest Atlantic Ocean comparing a new and a retiring vessel. For more than half of the species, conditional beta-binomial models performed better than binomial models, and accounting for random variation among pairs in the relative efficiency was important for all species. Source

Hoff G.R.,National Oceanic and Atmospheric Administration
Journal of Fish Biology | Year: 2016

The use of more than a single nursery habitat type is examined for oviparous elasmobranchs using data summarized from studies conducted on the Alaska skate Bathyraja parmifera and the Aleutian skate Bathyraja aleutica in the eastern Bering Sea. The eastern Bering Sea skate species use two discrete areas as nurseries, one for egg deposition and a second for newly emergent juveniles. Egg deposition sites were located along the outer shelf and upper slope near canyons in the eastern Bering Sea. Newly emergent juveniles were found along the outer and middle shelf for B. parmifera and deep-slope for B. aleutica, suggesting that habitat used by newly emergent juvenile skates is distinct from habitat used for egg deposition and embryo development. In reviewing many studies on oviparous elasmobranchs, similar patterns emerge of habitat use during their early life history. To distinguish these distinct habitats, appropriate terminology is proposed. Egg case nursery is suggested for areas of egg deposition and juvenile nursery is suggested for areas where juveniles aggregate after emergence. Criteria to describe each habitat type are outlined. © 2016 The Fisheries Society of the British Isles. Source

Mo K.C.,National Oceanic and Atmospheric Administration | Lyon B.,Columbia University
Journal of Hydrometeorology | Year: 2015

Precipitation forecasts from six climate models in the North American Multi-Model Ensemble (NMME) are combined with observed precipitation data to generate forecasts of the standardized precipitation index (SPI) for global land areas, and their skill was evaluated over the period 1982-2010. The skill of monthly precipitation forecasts from the NMME is also assessed. The value-added utility in using the NMME models to predict the SPI is identified by comparing the skill of its forecasts with a baseline skill based solely on the inherent persistence characteristics of the SPI itself. As expected, skill of the NMME-generated SPI forecasts depends on the season, location, and specific index considered (the 3- and 6-month SPI were evaluated). In virtually all locations and seasons, statistically significant skill is found at lead times of 1-2 months, although the skill comes largely from initial conditions. Added skill from the NMME is primarily in regions exhibiting El Niño-Southern Oscillation (ENSO) teleconnections. Knowledge of the initial drought state is critical in SPI prediction, and there are considerable differences in observed SPI values between different datasets. Root-mean-square differences between datasets can exceed typical thresholds for drought, particularly in the tropics. This is particularly problematic for precipitation products available in near-real time. Thus, in the near term, the largest advances in the global prediction of meteorological drought are obtainable from improvements in near-real-time precipitation observations for the globe. In the longer term, improvements in precipitation forecast skill from dynamical models will be essential in this effort. © Oxford University Press, 2015. Source

Snyder J.C.,University of Oklahoma | Ryzhkov A.V.,National Oceanic and Atmospheric Administration
Journal of Applied Meteorology and Climatology | Year: 2015

Although radial velocity data from Doppler radars can partially resolve some tornadoes, particularly large tornadoes near the radar, most tornadoes are not explicitly resolved by radar owing to inadequate spatiotemporal resolution. In addition, it can be difficult to determine which mesocyclones typically observed on radar are associated with tornadoes. Since debris lofted by tornadoes has scattering characteristics that are distinct from those of hydrometeors, the additional information provided by polarimetric weather radars can aid in identifying debris from tornadoes; the polarimetric tornadic debris signature (TDS) provides what is nearly "ground truth" that a tornado is ongoing (or has recently occurred). This paper outlines a modification to the hydrometeor classification algorithm used with the operational Weather Surveillance Radar-1988 Doppler (WSR-88D) network in the United States to include a TDS category. Examples of automated TDS classification are provided for several recent cases that were observed in the United States. © 2015 American Meteorological Society. Source

Sobash R.A.,University of Oklahoma | Wicker L.J.,National Oceanic and Atmospheric Administration
Monthly Weather Review | Year: 2015

Storm-scale ensemble Kalman filter (EnKF) studies routinely use methods to accelerate the spinup of convective structures when assimilating convective-scale radar observations. This typically involves adding coherent perturbations into analyses at regular intervals in regions where radar observations indicate convection is ongoing. Significant uncertainty remains as to the most effective use of these perturbations, including appropriate perturbation magnitudes, spatial scales, fields, and smoothing kernels, as well as flexible strategies that can be applied across a spectrum of convective events with negligible a priori tuning. Here, several idealized experiments were performed to elucidate the impact and sensitivity of adding coherent perturbations into storm-scale analyses of convection. Through the use of toy experiments, it is demonstrated that various factors exhibit substantial influence on the postsmoothed perturbation magnitudes, making tuning challenging. Several OSSEs were performed to document the impact of these perturbations on the analyses, particularly thermodynamic analyses within convection. The repeated addition of coherent perturbations produced temperature and moisture biases that are most pronounced in analyses of the surface cold pool and aloft near the tropopause, and eventually lead to biases in the dynamic fields. In an attempt to reduce these biases and make the noise procedure more adaptive, reflectivity innovations were used to restrict the addition of noise to areas where these innovations are large. This produced analyses with reduced thermodynamic biases and RMSE values comparable to the best-performing experiment where the noise magnitudes were manually adjusted. The impact of these findings on previous and future convective-scale EnKF analyses and forecasts are discussed. Source

Pothoven S.A.,National Oceanic and Atmospheric Administration | Madenjian C.P.,U.S. Geological Survey
North American Journal of Fisheries Management | Year: 2013

We evaluated the diet of Lake Whitefish Coregonus clupeaformis in Lake Huron during 2002-2011 to determine the importance of Round Goby Neogobius melanostomus and other fish as prey items. Lake Whitefish that had reached approximately 400 mm in length incorporated fish into their diets. The overall percentage of adult Lake Whitefish in Lake Huron that had eaten fish increased from 10% in 2002-2006 to 20% in 2007-2011, with a corresponding decrease in the frequency of Lake Whitefish that ate Dreissena spp. from 52% to 33%. During 2002-2006, Round Goby (wet mass, 38%), sculpins (Cottidae) (34%), and Ninespine Stickleback Pungitius pungitius (18%) were the primary fish eaten, whereas Round Goby accounted for 92% of the fish eaten in 2007-2011. Overall, Round Goby were found in the fewest Lake Whitefish stomachs in the north region of Lake Huron (6%) and in the most in the central (23%) and south (19%) regions of the lake. In the central region, Round Goby were eaten during all seasons that were sampled (spring through fall). In the south region, Round Goby were eaten only in the winter and spring but not in the summer when Dreissena spp. and spiny water flea Bythotrephes longimanus dominated the diet. Based on the 2007-2011 diet composition, an individual Lake Whitefish would need to have increased their consumption relative to that in 1983-1994 by 6% in the north region, 12% in the central region, and 41% in the southern region in order to achieve the same growth that was observed before dreissenid mussels arrived. However, Lake Whitefish weight adjusted for length only increased by 2% between 2002-2006 and 2007-2011 in the central region, decreased by 4% in the northern region, and remained constant in the southern region. This suggests that a shift toward more frequent piscivory does not necessarily improve the condition of a generalist feeder like Lake Whitefish. Received June 14, 2013; accepted August 28, 2013. © 2013 Copyright Taylor and Francis Group, LLC. Source

Funkhouser S.,National Oceanic and Atmospheric Administration
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2010

The change in entropy, ΔS, associated with the quasi-static absorption of a particle of energy ε by a Schwarzschild black hole (ScBH) is approximately (ε/T) - s, where T is the Hawking temperature of the black hole and s is the entropy of the particle. Motivated by the statistical interpretation of entropy, it is proposed here that the absorption should be suppressed, but not forbidden, when ΔS <0, which requires the absorption cross section to be sensitive to ΔS. A purely thermodynamic formulation of the probability for the absorption is obtained from the standard relationship between microstates and entropy. If ΔS 1 and s ε/T, then the probability for the particle not to be absorbed is approximately exp[-ε/T], which is identical to the probability for quantum mechanical reflection by the horizon of an ScBH. The manifestation of quantum behaviours in the new probability function may intimate a fundamental physical unity between thermodynamics and quantum mechanics. © 2010 The Royal Society. Source

Yuan Y.,National Climate Center | Yang S.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2012

Using multiple datasets and a partial correlation method, the authors analyze the different impacts of eastern Pacific (EP) and central Pacific (CP) El Niñoon East Asian climate, focusing on the features from El Niño developing summer to El Niño decaying summer. Unlike the positive-negative-positive (+/-/+) anomalous precipitation pattern over East Asia and the equatorial Pacific during EP El Niño, an anomalous -/+/- rainfall pattern appears during CP El Niño. The anomalous dry conditions over southeastern China and the northwestern Pacific during CP El Niño seem to result from the anomalous low-level anticyclone over southernChina andthe South China Sea, which is located more westward than the Philippine Sea anticyclone during EP El Niño. The continuous anomalous sinking motion over southeastern China, as part of the anomalous Walker circulation associated with CP El Niñ o, also contributes to these dry conditions. During the developing summer, the impact of CP El Niño on East Asian climate is more significant than the influence of EP El Niño. During the decaying summer, however, EP El Niño exerts a strongerinfluence on East Asia, probably due to the long-lasting anomalous warming over the tropical Indian Ocean accompanying EP El Niño. Temperaturesover portions of East Asia and the northwestern Pacific tend to be above normal during EP El Niño but below normal from the developing autumn to the next spring during CP El Niño. A possible reason is the weakened (enhanced) East Asian winter monsoon related to EP (CP) El Niño. © 2012 American Meteorological Society. Source

Gasparini S.,Louisiana State University Health Sciences Center | Gasparini S.,National Oceanic and Atmospheric Administration
Journal of Neurophysiology | Year: 2011

Layer V principal neurons of the medial entorhinal cortex receive the main hippocampal output and relay processed information to the neocortex. Despite the fundamental role hypothesized for these neurons in memory replay and consolidation, their dendritic features are largely unknown. Highspeed confocal and two-photon Ca2+ imaging coupled with somatic whole cell patch-clamp recordings were used to investigate spike back-propagation in these neurons. The Ca2+ transient associated with a single back-propagating action potential was considerably smaller at distal dendritic locations (>200 m from the soma) compared with proximal ones. Perfusion of Ba2+ (150 M) or 4-aminopyridine (2 mM) to block A-type K+ currents significantly increased the amplitude of the distal, but not proximal, Ca2+ transients, which is strong evidence for an increased density of these channels at distal dendritic locations. In addition, the Ca2+ transients decreased with each subsequent spike in a 20-Hz train; this activitydependent decrease was also more prominent at more distal locations and was attenuated by the perfusion of the protein kinase C activator phorbol-di-acetate. These data are consistent with a phosphorylationdependent control of back-propagation during trains of action potentials, attributable mainly to an increase in the time constant of recovery from voltage-dependent inactivation of dendritic Na+ channels. In summary, dendritic Na+ and A-type K+ channels control spike back-propagation in layer V entorhinal neurons. Because the activity of these channels is highly modulated, the extent of the dendritic Ca2+ influx is as well, with important functional implications for dendritic integration and associative synaptic plasticity. Source

Sun C.,National Climate Center | Yang S.,National Oceanic and Atmospheric Administration
Journal of Geophysical Research: Atmospheres | Year: 2012

Severe drought persisted in southern China from January to May in 2011. In this study, a statistical analysis is carried out to discuss the multiple possible impacting factors including La Nia, the North Atlantic Oscillation (NAO), and the thermal condition of the Tibetan Plateau (TP). The La Nia event in 2010-11 excited a lower-tropospheric anomalous cyclone over the northwestern Pacific, weakening the northwestern Pacific subtropical high and caused an eastward shift of the high. As a result, transportation of wet and warm moisture from tropical oceans to southern China decreased. The La Nia event also strengthened the upper-tropospheric East Asian jet stream and deepened the East Asian trough, favoring a southward intrusion of dry northerly flow from the Siberia. The La Nia condition in the previous two seasons also seemed to provide precursory signals for the drought. Moreover, in January-May 2011, the NAO was in a positive phase and it tended to excite stationary Rossby waves that were distributed along the sub-polar and subtropical waveguides, respectively. The sub-polar one induced an anomalous anticyclone over the Siberia, favoring a southward intrusion of high-latitude northerly flow to southern China. The subtropical one, associated possibly with the enhanced convection over the broad region from the Mediterranean to Sahara, was favorable for an influence of upper-tropospheric flow on southern China. The TP might also exert an influence on the drought by weakening the westerly flow to the southern flank of TP and reducing water vapor transport from the Bay of Bengal to southern China. © Copyright 2012 by the American Geophysical Union. Source

Baskett M.L.,University of California at Davis | Waples R.S.,National Oceanic and Atmospheric Administration
Conservation Biology | Year: 2013

Artificial propagation strategies often incur selection in captivity that leads to traits that are maladaptive in the wild. For propagation programs focused on production rather than demographic contribution to wild populations, effects on wild populations can occur through unintentional escapement or the need to release individuals into natural environments for part of their life cycle. In this case, 2 alternative management strategies might reduce unintended fitness consequences on natural populations: (1) reduce selection in captivity as much as possible to reduce fitness load (keep them similar), or (2) breed a separate population to reduce captive-wild interactions as much as possible (make them different). We quantitatively evaluate these 2 strategies with a coupled demographic-genetic model based on Pacific salmon hatcheries that incorporates a variety of relevant processes and dynamics: selection in the hatchery relative to the wild, assortative mating based on the trait under selection, and different life cycle arrangements in terms of hatchery release, density dependence, natural selection, and reproduction. Model results indicate that, if natural selection only occurs between reproduction and captive release, the similar strategy performs better. However, if natural selection occurs between captive release and reproduction, the different and similar strategies present viable alternatives to reducing unintended fitness consequences because of the greater opportunity to purge maladaptive individuals. In this case, the appropriate approach depends on the feasibility of each strategy and the demographic goal (e.g., increasing natural abundance, or ensuring that a high proportion of natural spawners are naturally produced). In addition, the fitness effects of hatchery release are much greater if hatchery release occurs before (vs. after) density-dependent interactions. Given the logistical challenges to achieving both the similar and different strategies, evaluation of not just the preferred strategy but also the consequences of failing to achieve the desired target is critical. © 2012 Society for Conservation Biology. Source

Mansell E.R.,National Oceanic and Atmospheric Administration
Journal of the Atmospheric Sciences | Year: 2010

In two-moment bulk microphysics schemes, the practice of using different weighted fall velocities for the various moments is known to lead to artificial growth in reflectivity values for fast-falling particles, particularly at the downward leading edge of a precipitation column. Two simple correction schemes that prevent these artifacts while still allowing some effects of size sorting are presented. The corrections are obtained by comparing particle number concentrations that result from two or three different sedimentation calculations. The corrections do not conserve particle number concentrations but do prevent spurious reflectivity growth automatically without the need to place ad hoc limits on mean particle size. Multimoment bulk microphysics schemes often have used inconsistent variables in terms of the appropriate advection equation (e.g., mass mixing ratio and particle number concentration). A brief review of consistent advection and turbulent mixing for such variables is presented to provide clarification. © 2010 American Meteorological Society. Source

Jenkins C.N.,Institute Pesquisas Ecologicas | Van Houtan K.S.,National Oceanic and Atmospheric Administration | Van Houtan K.S.,Duke University | Pimm S.L.,Duke University | Sexton J.O.,University of Maryland University College
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

Because habitat loss is the main cause of extinction, where and how much society chooses to protect is vital for saving species. The United States is well positioned economically and politically to pursue habitat conservation should it be a societal goal. We assessed the US protected area portfolio with respect to biodiversity in the country. New synthesis maps for terrestrial vertebrates, freshwater fish, and trees permit comparison with protected areas to identify priorities for future conservation investment. Although the total area protected is substantial, its geographic configuration is nearly the opposite of patterns of endemism within the country. Most protected lands are in the West, whereas the vulnerable species are largely in the Southeast. Private land protections are significant, but they are not concentrated where the priorities are. To adequately protect the nation's unique biodiversity, we recommend specific areas deserving additional protection, some of them including public lands, but many others requiring private investment. © 2015, National Academy of Sciences. All rights reserved. Source

Pavolonis M.J.,National Oceanic and Atmospheric Administration | Sieglaff J.,Cooperative Institute for Meteorological Satellite Studies | Cintineo J.,Cooperative Institute for Meteorological Satellite Studies
Journal of Geophysical Research D: Atmospheres | Year: 2015

A new approach for quantitatively detecting volcanic ash and dust from satellite has been developed. The Spectrally Enhanced Cloud Objects (SECO) algorithm utilizes a combination of radiative transfer theory, a statistical model, and image processing techniques to identify volcanic ash and dust clouds in satellite imagery with a very low false alarm rate. This fully automated technique is globally applicable (day and night) and can be adapted to a wide range of low Earth orbit and geostationary satellite sensors or even combinations of satellite sensors. The SECO algorithm consists of four primary components: conversion of satellite measurements into robust spectral metrics, application of a Bayesian method to estimate the probability that a given satellite pixel contains volcanic ash and/or dust, construction of cloud objects, and the selection of cloud objects deemed to have the physical attributes consistent with volcanic ash and/or dust clouds. The first two components of the SECO algorithm were described in Part 1 of this study. The final two components are described in this paper. In addition, case studies and a global analysis are utilized to illustrate the benefits of the SECO approach relative to the traditional "split window" ash/dust detection technique. The SECO algorithm can form the basis for more advanced applications such as volcanic cloud alerting and data assimilation. © 2015. American Geophysical Union. All Rights Reserved. Source

Wahl E.R.,National Oceanic and Atmospheric Administration | Smerdon J.E.,Lamont Doherty Earth Observatory
Geophysical Research Letters | Year: 2012

The performance of climate field reconstruction (CFR) and index reconstruction methods is evaluated using proxy and non-informative predictor experiments. The skill of both reconstruction methods is determined using proxy data targeting the western region of North America. The results are compared to those targeting the same region, but derived from non-informative predictors comprising red-noise time series reflecting the full temporal autoregressive structure of the proxy network. All experiments are performed as probabilistic ensembles, providing estimated Monte Carlo distributions of reconstruction skill. Results demonstrate that the CFR skill distributions from proxy data are statistically distinct from and outperform the corresponding skill distributions generated from non-informative predictors; similar relative performance is demonstrated for the index reconstructions. In comparison to the CFR results using proxy information, the index reconstructions exhibit similar skill in calibration, but somewhat less skill in validation and a tendency to underestimate the amplitude of the validation period mean. Copyright 2012 by the American Geophysical Union. Source

Holman K.D.,University of Wisconsin - Madison | Gronewold A.,National Oceanic and Atmospheric Administration | Notaro M.,University of Wisconsin - Madison | Zarrin A.,Ferdowsi University of Mashhad
Geophysical Research Letters | Year: 2012

Lake Superior, the northern-most of the Laurentian Great Lakes, is the largest (by surface area) freshwater lake on the planet. Due in part to its high water surface to land area ratio, over one-third of the Lake Superior basin water budget is derived from precipitation falling directly on the lake surface. For most of the Great Lakes (including Lake Superior), historical precipitation estimates extend back to the early 1880s, and are based primarily on land-based gauge measurements. While alternatives to gauge-based estimates have been explored, there is no clear history of applying regional climate models (RCMs) to improve historical over-lake precipitation estimates. To address this gap in regional research, and to advance the state-of-the-art in Great Lakes regional hydrological modeling, we compare 21years of output (1980-2000) from an RCM to conventional gauge-based precipitation estimates for the same time period over the Lake Superior basin. We find that the RCM, unlike the gauge-based method, simulates realistic variations in over-lake atmospheric stability, which propagate into basin-wide precipitation estimates with a relatively low over-lake to over-land precipitation ratio in warm months (roughly 0.7 to 0.8 in June, July, and August) and a relatively high over-lake to over-land precipitation ratio in cold months (roughly 1.3 to 1.4 in December and January), compared to gauge-based estimates. Our findings underscore a need to potentially update historical gauge-based precipitation estimates for large lake systems, including Lake Superior, and that RCMs appear to provide a robust and defensible basis for making those updates. Copyright 2012 by the American Geophysical Union. Source

Zheng J.,Ocean University of China | Liu Q.,Ocean University of China | Wang C.,National Oceanic and Atmospheric Administration | Zheng X.-T.,Ocean University of China
Climate Dynamics | Year: 2013

Observational data show that the dominant mode of the boreal winter rainfall anomalies in the tropical Indo-Western Pacific (IWP) is a west-east dipolar pattern, which is called the Indo-Western Pacific Dipole (IWPD) mode and is related to El Niño-Southern Oscillation. It is found that corresponded to the IWPD mode is a new atmospheric teleconnection pattern-a wave train pattern emitted from the IWP toward Asia and the northwest Pacific in winter. During the positive (negative) phase of the IWPD, the teleconnection pattern features the negative (positive) anomalies of 200-hPa geopotential height (H200) centered at 30°N, 110°E and the positive (negative) anomalies of H200 centered at 45°N, 140°E. The teleconnection pattern represents the dominant mode of the boreal winter H200 anomaly over Asia. A series of simple atmospheric model experiments are performed to confirm that this winter teleconnection pattern is induced by the heating anomalies associated with the IWPD, and the heating anomalies over the equatorial central Pacific are not important to this teleconnection pattern from the IWP toward Asia and the northeast Pacific. The IWPD is strengthened after the climate regime shift of the 1970s, which leads to a stronger teleconnection pattern. © 2012 Springer-Verlag. Source

Wang C.,National Oceanic and Atmospheric Administration | Li C.,CAS Institute of Atmospheric Physics | Li C.,University of Chinese Academy of Sciences | Mu M.,CAS Qingdao Institute of Oceanology | Duan W.,CAS Institute of Atmospheric Physics
Climate Dynamics | Year: 2013

The paper examines different impacts of eastern Pacific warm/cold (EPW/EPC) and central Pacific warm/cold (CPW/CPC) events on tropical cyclones (TCs) in the western North Pacific (WNP) by considering the early season of April-June (AMJ), the peak season of July-September (JAS) and the late season of October-December (OND). During AMJ, EPW (EPC) is associated with a significant increase of the TC genesis number in the southeastern (southwestern) sub-region of the WNP, but no class of El Niño-Southern Oscillation (ENSO) events shows a significant change in the TC lifetime and intensity. During JAS, EPW corresponds to an increase (decrease) of the TC genesis number in the southeastern (northwestern) sub-region, but CPW shows no significant change. EPC increases the TC genesis in the northwestern and northeastern sub-regions and decreases the genesis in the southwestern sub-region, whereas CPC suppresses the genesis in the southeastern sub-region. Both the lifetime and intensity of TCs are increased in EPW, but only a shortened lifetime is seen for CPC. During OND, EPW reduces the TC genesis in the southwestern and northwestern sub-regions, whereas CPW enhances the genesis in the southeastern sub-region. Over the South China Sea, CPW and CPC show a significant decrease and increase of the TC genesis, respectively. The TC lifetime is significantly longer in both EPW and CPW and shorter in EPC, and TCs tend to be more (less) intense in EPW (CPC). All of these variations are consistent with the development of ENSO-related SST anomalies during different seasons and are supported by distributions of the genesis potential index-a combination of large-scale oceanic and atmospheric factors that affect TC activity. TCs in the WNP mainly take the straight westward, northwestward and recurving tracks. During AMJ of EPW years, the TC steering flow patterns favor the recurving track and suppress the straight westward and northwestward tracks. During JAS, EPW is associated with the steering flows that are unfavorable for TCs to move northwestward or westward, whereas CPW favors the northwestward track and suppresses the straight westward track. The steering flow patterns during OND are similar to those during JAS, except that EPC may increase the possibility of the northwestward track. © 2012 Springer-Verlag (outside the USA). Source

Vargas-Angel B.,National Oceanic and Atmospheric Administration
Coral Reefs | Year: 2010

Despite the critical role of crustose coralline algae (CCA) in coral reef formation, maintenance, and ecology, little is known about coralline algal disease abundance, distribution, etiology, or the potential implications of declining CCA flora. This paper presents the first quantitative study of CCA disease on U. S. Pacific coral reefs, based on Rapid Ecological Assessments conducted at 337 discrete sites, at 42 different U. S.-Affiliated Pacific Islands and Atolls, within 5 major geographical regions: main Hawaiian Islands, Northwestern Hawaiian Islands, American Samoa, the Pacific Remote Island Areas (PRIA), and Guam and the Commonwealth of the Northern Mariana Islands (CNMI). Five major disease categories were enumerated, and a disease occurrence index was estimated, based on case counts relative to percent CCA cover. CCA disease occurrence exhibited considerable spatial variability both between and within islands/atolls, with some regions being disproportionately affected by disease. No diseases were observed at remote Johnston and Wake Atolls, or the main Hawaiian Islands. Diseases were rare in the Northwestern Hawaiian Islands and the Northern Mariana Islands; occasional to common around the PRIA, and common to abundant in American Samoa, Guam, and the Southern Mariana Islands. Pacific-wide, disease occurrence was statistically associated with CCA percent cover and sea surface temperatures (SSTs) but not with human population density; nonetheless, disease occurrence and population density were statistically correlated for those islands containing disease. Although Pacific-wide, the occurrence of disease was low, with no active outbreaks detected in any region, hot spots of disease were detected around Guam, the southern CNMI, American Samoa, and the PRIA. The high levels of spatial and temporal variability in disease occurrence herein underscore the patchy nature and fluctuating distribution dynamics of these afflictions. Also, the widespread dispersal capabilities and extraordinary infective properties of some of these pathogens highlight the importance of better understanding CCA disease dynamics and discerning the relative threat levels on coral reef ecosystems. © 2010 US Government. Source

Hoff G.R.,National Oceanic and Atmospheric Administration
Marine Ecology Progress Series | Year: 2010

Identification of habitat used for skate egg deposition has been rarely studied or reported worldwide. Four nursery sites for the Alaska skate Bathyraja parmifera, 2 for the Aleutian skate B. aleutica and 2 for the Bering skate B. interrupta were identified along the upper continental slope in the eastern Bering Sea. All sites were located near undersea canyons from 145 to 380 m depth in relatively flat sandy to muddy bottom habitat. Bottom temperatures were relatively constant throughout the year, varying from 3.7 to 4.6°C. Egg case densities varied between nursery sites and were encountered at the Alaska skate nursery in Bering Canyon at densities greater than 800 000 eggs km-2. Based on egg case composition, sites were predominantly used by a single skate species for egg deposition; however, up to 6 skate species used the habitat commonly. Seasonal sampling indicated that sites were continuously occupied throughout the year, and embryo length composition showed multiple cohorts developing simultaneously. Data from bottom trawl surveys suggest juvenile skates occupy habitats different than nursery sites. The movement of juvenile skates out of nursery habitat after hatching may lessen predation by common predators such as the Pacific cod Gadus macrocephalus and the Pacific halibut Hippoglossus stenolepis. © Inter-Research 2010. Source

Bali M.,University of Maryland University College | Collins D.,National Oceanic and Atmospheric Administration
Climate Dynamics | Year: 2015

Soil moisture and phenology are seasonally varying modes of the land system. Due to their seasonal persistence, they have the ability to predictably influence seasonal weather. Hence, their use in seasonal forecasts can potentially improve the skill of the forecasts. However a complete measure of their influence in geographical locations and in different seasons is not known. As a result, modern seasonal forecasting techniques have not been able to fully exploit their persistence in improving skill of seasonal forecasts. By measuring similarity between model ensemble members that are forced by soil moisture and phenology respectively, in this study, we identify global hot spots where soil moisture and phenology impact key atmospheric variables in spring and summer seasons. Results indicate that over South East Asia (SEA) and the Sahel the phenology and soil moisture impact precipitation to an equal extent. Results show that 5–7 % of the variance in Indian summer monsoon precipitation is caused by soil moisture and phenology anomalies. Prior to the monsoon they influence predictors of the SEA monsoon. Hence, their persistence can be used to improve skill of seasonal forecasts, particularly of mesoscale systems like the SEA monsoon. © 2015 Springer-Verlag Berlin Heidelberg Source

Waples R.S.,National Oceanic and Atmospheric Administration
Molecular Ecology Resources | Year: 2010

The concept of effective population size (Ne) is based on an elegantly simple idea which, however, rapidly becomes very complex when applied to most real-world situations. In natural populations, spatial and temporal stratifications create different classes of individuals with different vital rates, and this in turn affects (generally reduces) Ne in complex ways. I consider how these natural stratifications influence our understanding of effective size and how to estimate it, and what the consequences are for conservation and management of natural populations. Important points that emerge include the following:1. The relative influences of local vs metapopulation Ne depend on a variety of factors, including the time frame of interest.2. Levels of diversity in local populations are strongly influenced by even low levels of migration, so these measures are not reliable indicators of local Ne.3. For long-term effective size, obtaining a reliable estimate of mutation rate is the most important consideration; unless this is accomplished, estimates can be biased by orders of magnitude.4. At least some estimators of contemporary Ne appear to be robust to relatively high (approximately 10%) equilibrium levels of migration, so under many realistic scenarios they might yield reliable estimates of local Ne.5. Age structure probably has little effect on long-term estimators of Ne but can strongly influence contemporary estimates.6. More research is needed in several key areas: (i) to disentangle effects of selection and drift in metapopulations connected by intermediate levels of migration; (ii) to elucidate the relationship between Nb (effective number of breeders per year) and Ne per generation in age-structured populations; (iii) to perform rigorous sensitivity analyses of new likelihood and coalescent-based methods for estimating demographic and evolutionary histories. Published 2010. This article is a US Government work and is in the public domain in the USA. Source

White J.W.,University of North Carolina at Wilmington | Rassweiler A.,University of California at Santa Barbara | Samhouri J.F.,National Oceanic and Atmospheric Administration | Stier A.C.,University of British Columbia | White C.,California Polytechnic State University, San Luis Obispo
Oikos | Year: 2014

Simulation models are widely used to represent the dynamics of ecological systems. A common question with such models is how changes to a parameter value or functional form in the model alter the results. Some authors have chosen to answer that question using frequentist statistical hypothesis tests (e.g. ANOVA). This is inappropriate for two reasons. First, p-values are determined by statistical power (i.e. replication), which can be arbitrarily high in a simulation context, producing minuscule p-values regardless of the effect size. Second, the null hypothesis of no difference between treatments (e.g. parameter values) is known a priori to be false, invalidating the premise of the test. Use of p-values is troublesome (rather than simply irrelevant) because small p-values lend a false sense of importance to observed differences. We argue that modelers should abandon this practice and focus on evaluating the magnitude of differences between simulations. © 2013. Source

Churnside J.H.,National Oceanic and Atmospheric Administration
Optical Engineering | Year: 2014

This paper provides a review of the development of profiling oceanographic lidars. These can provide quantitative profiles of the optical properties of the water column to depths of 20 to 30min productive coastal waters and to depths of 100 m for a blue lidar in the open ocean. The properties that can be measured include beam attenuation, diffuse attenuation, absorption, volume scattering at the scattering angle of 180 deg, and total backscattering. Lidar can be used to infer the relative vertical distributions of fish, plankton, bubbles, and other scattering particles. Using scattering as a tracer, lidar can provide information on the dynamics of the upper ocean, including mixed-layer depth, internal waves, and turbulence. Information in the polarization of the lidar return has been critical to the success of many of these investigations. Future progress in the field is likely through a better understanding of the variability of the lidar ratio and the application of high-spectral-resolution lidar to the ocean. Somewhat farther into the future, capabilities are likely to include lidar profiling of temperature in the ocean and an oceanographic lidar in space. © The Authors. Source

Carey M.P.,University of Illinois at Urbana - Champaign | Carey M.P.,National Oceanic and Atmospheric Administration | Wahl D.H.,University of Illinois at Urbana - Champaign
Ecology | Year: 2010

Aquatic communities have been altered by invasive species, with impacts on native biodiversity and ecosystem function. At the same time, native biodiversity may mitigate the effects of an invader. Common carp (Cyprinus carpio) is a ubiquitous, invasive fish species that strongly influences community and ecosystem processes. We used common carp to test whether the potential effects of an invasive species are altered across a range of species diversity in native communities. in mesocosms, treatments of zero, one, three, and six native fish species were used to represent the nested subset patterns observed in fish communities of lakes in Illinois, USA. The effect of the invader was tested across fish richness treatments by adding common carp to the native community and substituting native biomass with common carp. Native species and intraspecific effects reduced invader growth. The invader reduced native fish growth; however, the negative effect was minimized with increasing native richness. The zooplankton grazer community was modified by a top-down effect from the invader that increased the amount of phytoplankton. Neither the invader nor richness treatments influenced total phosphorus or community metabolism. Overall, the invader reduced resources for native species, and the effect scaled with how the invader was incorporated into the community. Higher native diversity mitigated the impact of the invader, confirming the need to consider biodiversity when predicting the impacts of invasive species. © 2010 by the Ecological Society of America. Source

Kasperski S.,National Oceanic and Atmospheric Administration
Environmental and Resource Economics | Year: 2015

Single-species management of multi-species fisheries ignores ecological interactions in addition to important economic interactions to the detriment of the health of the ecosystem, the stocks of fish species, and fishery profits. This study maximizes the net present value from a multi-species fishery where species interact ecologically in the ecosystem, and economically through vessels’ multi-product harvesting technology, switching gear types, and interactions in output markets. Numerical optimization techniques are used to determine the optimal harvest quota of each species over time. This study highlights the need to incorporate both ecological and economic interactions that occur between species in an ecosystem. © 2014, US Government. Source

Putman N.F.,National Oceanic and Atmospheric Administration
Integrative and Comparative Biology | Year: 2015

Migration in animals has evolved as an adaptation to environmental variability across space and through time. The availability of reliable sensory cues and guidance mechanisms used in navigating among disparate locations is an essential component of this behavior. An "inherited magnetic map" is navigational solution that has evolved in some marine animals that, without prior experience or guidance from older conspecifics, migrate to oceanic foraging grounds. Laboratory experiments demonstrate that navigationally naïve salmon encountering magnetic fields characteristic of certain regions along their migratory route will bias their swimming in a particular direction. Simulations of this behavior within realistic models of oceanic circulation suggest that such behavior is highly adaptive, making the migratory route more predictable and facilitating movement into favorable oceanic regions. Such behavior is possible due to the spatial gradients of components of the geomagnetic field (e.g., the inclination angle of field lines and the total field intensity) that provide a bicoordinate grid across much of the Earth's surface. However, this environmental feature is not static, but experiences gradual and unpredictable changes that can be substantial over successive generations. Thus, drift of the geomagnetic field, in addition to variable oceanic conditions, could play a major role in shaping the distribution of marine taxa that are dependent upon such mechanisms for migratory guidance. Several possibilities are discussed for how animals might mitigate the effects of geomagnetic drift, such as calibrating their inherited magnetic map relative to the field in which they develop. Further exploration of the dynamics of the geomagnetic field in context of animal navigation is a promising avenue for understanding the how animals deal with an ever-changing environment. © 2015 The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com. Source

Overland J.E.,National Oceanic and Atmospheric Administration | Wood K.R.,University of Washington | Wang M.,University of Washington
Polar Research | Year: 2011

Recent Arctic changes are likely due to coupled Arctic amplification mechanisms with increased linkage between Arctic climate and sub-Arctic weather. Historically, sea ice grew rapidly in autumn, a strong negative radiative feedback. But increased sea-ice mobility, loss of multi-year sea ice, enhanced heat storage in newly sea ice-free ocean areas, and modified wind fields form connected positive feedback processes. One-way shifts in the Arctic system are sensitive to the combination of episodic intrinsic atmospheric and ocean variability and persistent increasing greenhouse gases. Winter 2009/10 and December 2010 showed a unique connectivity between the Arctic and more southern weather patterns when the typical polar vortex was replaced by high geopotential heights over the central Arctic and low heights over mid-latitudes that resulted in record snow and low temperatures, a warm Arctic-cold continents pattern. The negative value of the winter (DJF 2009/10) North Atlantic Oscillation (NAO) index associated with enhanced meridional winds was the lowest observed value since the beginning of the record in 1865. Wind patterns in December 2007 and 2008 also show an impact of warmer Arctic temperatures. A tendency for higher geopotential heights over the Arctic and enhanced meridional winds are physically consistent with continued loss of sea ice over the next 40 years. A major challenge is to understand the interaction of Arctic changes with climate patterns such as the NAO, Pacific North American and El Niño-Southern Oscillation. © 2011 J.E. Overland et al. Source

Waples R.S.,National Oceanic and Atmospheric Administration
Journal of Heredity | Year: 2015

Testing for Hardy-Weinberg proportions (HWP) is routine in almost all genetic studies of natural populations, but many researchers do not demonstrate a full understanding of the purposes of these tests or how to interpret the results. Common problems include a lack of understanding of statistical power and the difference between statistical significance and biological significance, how to interpret results of multiple tests, and how to distinguish between various factors that can cause statistically significant departures. In this perspective, which focuses on analysis of genetic data for nonmodel species, I 1) review factors that can cause departures from HWP at individual loci and linkage disequilibrium (LD) at pairs of loci; 2) discuss commonly used tests for HWP and LD, with an emphasis on multiple-testing issues; 3) show how to distinguish among possible causes of departures from HWP; and 4) outline some simple steps to follow when significant test results are found. Finally, I 5) identify some issues that merit particular attention as we move into an era in which analysis of genomics-scale datasets for nonmodel species is commonplace. Source

Lemoine D.,University of Arizona | Kapnick S.,National Oceanic and Atmospheric Administration
Nature Climate Change | Year: 2016

To evaluate policies to reduce greenhouse-gas emissions, economic models require estimates of how future climate change will affect well-being. So far, nearly all estimates of the economic impacts of future warming have been developed by combining estimates of impacts in individual sectors of the economy. Recent work has used variation in warming over time and space to produce top-down estimates of how past climate and weather shocks have affected economic output. Here we propose a statistical framework for converting these top-down estimates of past economic costs of regional warming into projections of the economic cost of future global warming. Combining the latest physical climate models, socioeconomic projections, and economic estimates of past impacts, we find that future warming could raise the expected rate of economic growth in richer countries, reduce the expected rate of economic growth in poorer countries, and increase the variability of growth by increasing the climateâ ?(tm) s variability. This study suggests we should rethink the focus on global impacts and the use of deterministic frameworks for modelling impacts and policy. © 2015 Macmillan Publishers Limited. Source

Lee M.-Y.,National Oceanic and Atmospheric Administration
Marine Resource Economics | Year: 2014

Atlantic cod (Gadus morhua) has been culturally important in the northeast United States (US) for hundreds of years. This research estimates a hedonic model of cod prices in the Northeast US from 2005-2011. While large fish typically receive premium prices, the largest cod receive prices that are approximately $0.20 per pound lower than fish in the next largest market category. A moderate premium for freshness is found: cod caught on trips that last four days receive $0.04 less per pound than fish that is caught on shorter trips. This discount rises to nearly $0.15 per pound for trips lasting 10 days or longer. A similar discount exists for fish that are stored for two or more days after landing. The premia estimated by the hedonic price model are quite different from the group mean premia, suggesting that bioeconomic models that incorporate price heterogeneity should consider more sophisticated price models. © 2011 MRE Foundation, Inc. All rights reserved. Source

Manzello D.P.,National Oceanic and Atmospheric Administration
Coral Reefs | Year: 2010

The rapid growth of scleractinian corals is responsible for the persistence of coral reefs through time. Coral growth rates have declined over the past 30 years in the western Pacific, Indian, and North Atlantic Oceans. The spatial scale of this decline has led researchers to suggest that a global phenomenon like ocean acidification may be responsible. A multi-species inventory of coral growth from Pacific Panamá confirms that declines have occurred in some, but not all species. Linear extension declined significantly in the most important reef builder of the eastern tropical Pacific, Pocillopora damicornis, by nearly one-third from 1974 to 2006. The rate of decline in skeletal extension for P. damicornis from Pacific Panamá (0. 9% year -1) was nearly identical to massive Porites in the Indo-Pacific over the past 20-30 years (0.89-1.23% year -1). The branching pocilloporid corals have shown an increased tolerance to recurrent thermal stress events in Panamá, but appear to be susceptible to acidification. In contrast, the massive pavonid corals have shown less tolerance to thermal stress, but may be less sensitive to acidification. These differing sensitivities will be a fundamental determinant of eastern tropical Pacific coral reef community structure with accelerating climate change that has implications for the future of reef communities worldwide. © 2010 Springer-Verlag. Source

Byron C.J.,University of Rhode Island | Link J.S.,National Oceanic and Atmospheric Administration
Marine Ecology Progress Series | Year: 2010

Evidence of species interactions are generally well understood over broad temporal and spatial scales, particularly for commercially valuable species. Yet species that are not as commercially valuable may nonetheless be ecologically important in stabilizing trophic interactions in large marine ecosystems. We examined the diets for 4 of these demersal fish species: black sea bass Centropristis striata, scup Stenotomus chrysops, Northern searobin Prionotus carolinus, and striped searobin P. evolans. We examined food habits data across size class, season, 5 yr time block, and geographic region to evaluate the major determinants of diet composition. We used multivariate statistics, specifically canonical correspondence analysis, as the primary method to explore diet determinants. Our results showed that the scup and 2 searobin species are primarily benthivorous, whereas black sea bass notably shifts towards piscivory with ontogeny. Our results also showed that the diet of these predators was mainly influenced by size class, region, and (to a lesser extent) season, whereas 5 yr time block did not notably influence diet composition, a surprising observation given the welldocumented changes to benthic habitat in this ecosystem. These results suggest that these species feed opportunistically in proportion to the relative abundance of available prey given the constraints of their morphology, which implies that despite notable impacts to benthic habitat, the prey field for these understudied species has been consistent (within seasonal variation) over the past 3 decades. Stable feeding dynamics such as these may act to enhance resilience in large marine ecosystems. © Inter-Research 2010. Source

Zhang J.,National Oceanic and Atmospheric Administration | Qi Y.,Nanjing University of Information Science and Technology | Qi Y.,University of Oklahoma
Journal of Hydrometeorology | Year: 2010

The bright band (BB) is a layer of enhanced reflectivity due to melting of aggregated snow and ice crystals. The locally high reflectivity causes significant overestimation in radar precipitation estimates if an appropriate correction is not applied. The main objective of the current study is to develop a method that automatically corrects for large errors due to BB effects in a real-time national radar quantitative precipitation estimation (QPE) product. An approach that combines the mean apparent vertical profile of reflectivity (VPR) computed from a volume scan of radar reflectivity observations and an idealized linear VPR model was used for computational efficiency. The methodology was tested for eight events from different regions and seasons in the United States. The VPR correction was found to be effective and robust in reducing overestimation errors in radar-derived QPE, and the corrected radar precipitation fields showed physically continuous distributions. The correction worked consistently well for radars in flat land regions because of the relatively uniform spatial distributions of the BB in those areas. For radars in mountainous regions, the performance of the correction is mixed because of limited radar visibility in addition to large spatial variations of the vertical precipitation structure due to underlying topography. © 2010 American Meteorological Society. Source

Bejarano A.C.,Research Planning | Farr J.K.,National Oceanic and Atmospheric Administration
Environmental Toxicology and Chemistry | Year: 2013

Management decisions aimed at protecting aquatic resources following accidental chemical spills into rivers and coastal estuaries require estimates of toxic thresholds derived from realistic spill conditions: acute pulse exposures of short duration (h), information which often is unavailable. Most existing toxicity data (median lethal concentration or median effective concentration) come from tests performed under constant exposure concentrations and exposure durations in the 24-h to 96-h range, conditions not typical of most chemical spills. Short-exposure hazard concentration estimates were derived for selected chemicals using empirical toxicity data. Chemical-specific 5th percentile hazard concentrations (HC5) of species sensitivity distributions (SSD) from individual exposure durations (6-96h) were derived via bootstrap resampling and were plotted against their original exposure durations to estimate HC5s and 95% confidence intervals (CIs) at shorter exposures (1, 2, and 4h). This approach allowed the development of short-exposure HC5s for 12 chemicals. Model verification showed agreement between observed and estimated short-exposure HC5s (r2 adjusted=0.95, p<0.0001), and comparison of estimated short-exposure HC5s with empirical toxicity data indicated generally conservative hazard estimates. This approach, applied to 2 real spill incidents, indicated hazard estimates above expected environmental concentrations (acrylonitrile), and suggested that environmental concentrations likely exceeded short-exposure hazard estimates (furfural). Although estimates generated through this approach were likely overprotective, these were derived from environmentally realistic exposure durations, providing risk-assessors with a tool to manage field decisions. © 2013 SETAC. Source

Stumpf R.P.,National Oceanic and Atmospheric Administration | Werdell P.J.,Science Systems And Applications Inc.
Optics Express | Year: 2010

The band-by-band vicarious calibration of on-orbit satellite ocean color instruments, such as SeaWiFS and MODIS, using ground-based measurements has significant residual uncertainties. This paper applies spectral shape and population statistics to tune the calibration of the blue bands against each other to allow examination of the interband calibration and potentially provide an analysis of calibration trends. This adjustment does not require simultaneous matches of ground and satellite observations. The method demonstrates the spectral stability of the SeaWiFS calibration and identifies a drift in the MODIS instrument onboard Aqua that falls within its current calibration uncertainties. © 2010 Optical Society of America. Source

Pirtle J.L.,University of Alaska Fairbanks | Stoner A.W.,National Oceanic and Atmospheric Administration
Journal of Experimental Marine Biology and Ecology | Year: 2010

Little is known about nursery habitat function for red king crab (Paralithodes camtschaticus), a commercially important species that associates with complex benthic habitats from settlement through the first two years of life. During settlement, the red king crab actively seeks complex benthic habitats, with high availability of vertical structure and crevice space. Habitat choice for early juvenile red king crab may be driven by habitat complexity, or a function of several potential mechanisms, including foraging requirements, and shifting ontogeny. We established habitat preference and foraging behavior for two size classes of age-0 red king crab (small 2-4. mm, and large 7.5-9. mm carapace length) with laboratory experiments using habitat treatments composed of individual complex substrates that were living, biogenic substrates, including structural invertebrates, bryozoans and hydroids, and macroalgae in branched and blade forms. Non-living structural mimics of the biogenic substrates were presented to crabs as clean and fouled mimic treatments. We quantified the proportion of crab associations and foraging activity with single habitat treatments within a 24. h period. Substrates that were statistically attractive to small crabs were paired to test small crab foraging behavior. A variety of substrates were statistically attractive to red king crab. Small crabs associated with complex biogenic habitats and fouled mimics (group mean ± SE 64% ± 4%) more often than clean mimics (29% ± 4%), and preferred to forage on the structural invertebrates (foraging frequency 81%) when presented with paired biogenic and fouled mimic substrates. Large crabs associated with habitats composed of structural invertebrates (group mean ± SE 78% ± 2%) statistically more often than macroalgae and fouled and clean mimics (32% ± 5%). Strong attraction to structural invertebrates by early juvenile red king crab is likely driven by foraging opportunities. Our experiments demonstrate that biological habitat features may be functionally more important to early juvenile red king crab than complex physical structure alone. Habitats formed by structural invertebrates, in particular, may enhance growth and survival of early post-settlement stage red king crab in excess of other highly structured habitats, including macroalgae and complex physical substrates. © 2010 Elsevier B.V. Source

Schaefer K.,University of Colorado at Boulder | Zhang T.,University of Colorado at Boulder | Bruhwiler L.,National Oceanic and Atmospheric Administration | Barrett A.P.,University of Colorado at Boulder
Tellus, Series B: Chemical and Physical Meteorology | Year: 2011

The thaw and release of carbon currently frozen in permafrost will increase atmospheric CO2 concentrations and amplify surface warming to initiate a positive permafrost carbon feedback (PCF) on climate. We use surface weather from three global climate models based on the moderate warming, A1B Intergovernmental Panel on Climate Change emissions scenario and the SiBCASA land surface model to estimate the strength and timing of the PCF and associated uncertainty. By 2200, we predict a 29-59% decrease in permafrost area and a 53-97 cm increase in active layer thickness. By 2200, the PCF strength in terms of cumulative permafrost carbon flux to the atmosphere is 190 ± 64 Gt C. This estimate may be low because it does not account for amplified surface warming due to the PCF itself and excludes some discontinuous permafrost regions where SiBCASA did not simulate permafrost. We predict that the PCF will change the arctic from a carbon sink to a source after the mid-2020s and is strong enough to cancel 42-88% of the total global land sink. The thaw and decay of permafrost carbon is irreversible and accounting for the PCF will require larger reductions in fossil fuel emissions to reach a target atmospheric CO2 concentration. Tellus B©2011 John Wiley & Sons A/S No claim to original US government works. Source

Ndiaye O.,Columbia University | Ward M.N.,Columbia University | Thiaw W.M.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2011

The ability of several atmosphere-only and coupled ocean-atmosphere general circulation models (AGCMs and CGCMs, respectively) is explored for the prediction of seasonal July-September (JAS) Sahel rainfall. The AGCMs driven with observed sea surface temperature (SST) over the period 1968-2001 confirm the poor ability of such models to represent interannual Sahel rainfall variability. However, using a model output statistics (MOS) approach with the predicted low-level wind field over the tropical Atlantic and western part of West Africa yields good Sahel rainfall skill for all models. Skill is mostly captured in the leading empirical orthogonal function (EOF1), representing large-scale fluctuation in the regional circulation system over the tropical Atlantic. This finding has operational significance for the utility of AGCMs for short lead-time prediction based on persistence of June SST information; however, studies have shown that for longer lead-time forecasts, there is substantial loss of skill, relative to that achieved using the observed JAS SST. The potential of CGCMs is therefore explored for extending the lead time of Sahel rainfall predictions. Some of the models studied, when initialized using April information, show potential to at least match the levels of skill achievable from assuming persistence of April SST. One model [NCEP Climate Forecasting System (CFS)] was found to be particularly promising. Diagnosis of the hindcasts available for the CFS (from lead times up to six months for 1981-2008) suggests that, especially by applying the same MOSapproach, skill is achieved through capturing interannual variations in Sahel rainfall (primarily related to El Niño-Southern Oscillation in the period of study), as well as the upward trend in Sahel rainfall that is observed over 1981-2008, which has been accompanied by a relative warming in the North Atlantic compared to the South Atlantic. At lead times up to six months (initialized forecasts in December), skill levels are maintained with the correlation between predicted and observed Sahel rainfall at approximately r 5 0.6. While such skill levels at these long lead times are notably higher than previously achieved, further experiments, such as over the same period and with comparable AGCMs, are required for definitive attribution of the advance to the use of a coupled ocean-atmosphere modeling approach. Nonetheless, the detrended skill achieved here by the January-March initializations (r = 0.33) must require an approach that captures the evolution of the key ocean-atmosphere anomalies from boreal winter to boreal summer, and approaches that draw on persistence in ocean conditions have not previously been successful. © 2011 American Meteorological Society. Source

Furtado J.C.,Georgia Institute of Technology | Furtado J.C.,Atmospheric and Environmental Research Inc. | Di Lorenzo E.,Georgia Institute of Technology | Schneider N.,University of Hawaii at Manoa | Bond N.A.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2011

The two leading modes of North Pacific sea surface temperature (SST) and sea level pressure (SLP), as well as their connections to tropical variability, are explored in the 24 coupled climate models used in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) to evaluate North Pacific decadal variability (NPDV) in the past [twentieth century; climate of the twentieth century (20C3M) scenario] and future [twenty-first century; Special Report on Emissions Scenarios (SRES) A1B scenario] climate. Results indicate that the two dominant modes of North Pacific oceanic variability, the Pacific decadal oscillation (PDO) and the North Pacific Gyre Oscillation (NPGO), do not exhibit significant changes in their spatial and temporal characteristics under greenhouse warming. However, the ability of the models to capture the dynamics associated with the leading North Pacific oceanic modes, including their link to the corresponding atmospheric forcing patterns and to tropical variability, is questionable. The temporal and spatial statistics of the North Pacific Ocean modes exhibit significant discrepancies from observations in their twentieth-century climate, most visibly for the second mode, which has significantly more low-frequency power and higher variance than in observations. The dynamical coupling between the North Pacific Ocean and atmosphere modes evident in the observations is very strong in the models for the first atmosphere-ocean coupled mode, which represents covariability of the PDO pattern with the Aleutian low (AL). However, the link for the second atmosphere-ocean coupled mode, describing covariability of an NPGO-like SST pattern with the North Pacific Oscillation (NPO), is not as clearly reproduced, with some models showing no relationship between the two. Exploring the tropical Pacific-North Pacific teleconnections reveals more issues with the models. In contrast with observations, the atmospheric teleconnection excited by the El Niño-Southern Oscillation in the models does not project strongly on the AL-PDO coupled mode because of the displacement of the center of action of the AL in most models. Moreover, most models fail to show the observational connection between El Niño Modoki-central Pacific warming and NPO variability in the North Pacific. In fact, the atmospheric teleconnections associated with El Niño Modoki in some models have a significant projection on, and excite the AL-PDO coupled mode instead. Because of the known links between tropical Pacific variability and NPDV, these analyses demonstrate that focus on the North Pacific variability of climate models in isolation from tropical dynamics is likely to lead to an incomplete view, and inadequate prediction, of NPDV. © 2011 American Meteorological Society. Source

Palecki M.A.,National Oceanic and Atmospheric Administration | Groisman P.Y.,U.S. National Center for Atmospheric Research
Journal of Hydrometeorology | Year: 2011

The U.S. Climate Reference Network (USCRN) was deployed between 2001 and 2008 for the purpose of yielding high-quality and temporally stable in situ climate observations in pristine environments over the twenty-first century. Given this mission, USCRN stations are engineered to operate largely autonomously with great reliability and accuracy. A triplicate approach is used to provide redundant measurements of temperature and precipitation at each location, allowing for observations at a specific time to be compared for quality control. This approach has proven to be robust in the most extreme environments, from extreme cold (-49°C) to extreme heat (+52°C), in areas of heavy precipitation (4700 mm yr -1), and in locations impacted by strong winds, freezing rain, and other hazards. In addition to a number of stations enduring extreme winter environments in Alaska and the northern United States, seven of the USCRN stations are located at elevations over 2000 m, including stations on Mauna Loa, Hawaii (3407 m) and on Niwot Ridge above Boulder, Colorado (2996 m). The USCRN temperature instruments and radiation shield have also been installed and run successfully at a station on the Quelccaya Ice Cap in Peru (5670 m). This paper reviews the performance of the USCRN station network during its brief lifetime and the potential utility of its triplicate temperature instrument configuration for measuring climate change at elevation. © 2011 American Meteorological Society. Source

Mayer T.D.,U.S. Fish and Wildlife Service | Naman S.W.,National Oceanic and Atmospheric Administration
Journal of the American Water Resources Association | Year: 2011

This study examines the regional streamflow response in 25 predominately unregulated basins to warmer winter temperatures and snowpack reductions over the last half century in the Klamath Basin of California and Oregon. Geologic controls of streamflow in the region result in two general stream types: surface-dominated and groundwater-dominated basins. Surface-dominated basins were further differentiated into rain basins and snowmelt basins on the basis of elevation and timing of winter runoff. Streamflow characteristics and response to climate vary with stream type, as discussed in the study. Warmer winter temperatures and snowpack reductions have caused significantly earlier runoff peaks in both snowmelt and groundwater basins in the region. In the groundwater basins, the streamflow response to changes in snowpack is smoothed and delayed and the effects are extended longer in the summer. Our results indicate that absolute decreases in July-September base flows are significantly greater, by an order of magnitude, in groundwater basins compared to surface-dominated basins. The declines are important because groundwater basins sustain Upper Klamath Lake inflows and mainstem river flows during the typically dry summers of the area. Upper Klamath Lake April-September net inflows have decreased an estimated 16% or 84thousand acre-feet (103.6Mm 3) since 1961, with the summer months showing proportionately more decline. These changes will exacerbate water supply problems for agriculture and natural resources in the region. © 2011 American Water Resources Association. This article is a U.S. Government work and is in the public domain in the USA. Source

Yashayaev I.,Bedford Institute of Oceanography | Seidov D.,National Oceanic and Atmospheric Administration
Progress in Oceanography | Year: 2015

The focus of this work is on the temporal and spatial variability of the Atlantic Water (AW). We analyze the existing historic hydrographic data from the World Ocean Database to document the long-term variability of the AW throughflow across the Norwegian Sea to the western Barents Sea. Interannual-to-multidecadal variability of water temperature, salinity and density are analyzed along six composite sections crossing the AW flow and coastal currents at six selected locations. The stations are lined up from southwest to northeast - from the northern North Sea (69°N) throughout the Norwegian Sea to the Kola Section in the Barents Sea (33°30'E). The changing volume and characteristics of the AW throughflow dominate the hydrographic variability on decadal and longer time scales in the studied area. We examine the role of fluctuations of the volume of inflow versus the variable local factors, such as the air-sea interaction and mixing with the fresh coastal and cold Arctic waters, in controlling the long-term regional variability. It is shown that the volume of the AW, passing through the area and affecting the position of the outer edge of the warm and saline core, correlates well with temperature and salinity averaged over the central portions of the studied sections. The coastal flow (mostly associated with the Norwegian Coastal Current flowing over the continental shelf) is largely controlled by seasonal local heat and freshwater impacts. Temperature records at all six lines show a warming trend superimposed on a series of relatively warm and cold periods, which in most cases follow, with a delay of four to five years, the periods of relatively low and high North Atlantic Oscillation (NAO), and the periods of relatively high and low Atlantic Multidecadal Oscillation (AMO), respectively. In general, there is a relatively high correlation between the year-to-year changes of the NAO and AMO indices, which is to some extent reflected in the (delayed) AW temperature fluctuations. It takes about two years for freshening and salinification events and a much shorter time (of about a year or less) for cooling and warming episodes to propagate or spread across the region. This significant difference in the propagation rates of salinity and temperature anomalies is explained by the leading role of horizontal advection in the propagation of salinity anomalies, whereas temperature is also controlled by the competing air-sea interaction along the AW throughflow. Therefore, although a water parcel moves within the flow as a whole, the temperature, salinity and density anomalies split and propagate separately, with the temperature and density signals leading relative to the salinity signal. A new hydrographic index, coastal-to-offshore density step, is introduced to capture variability in the strength of the AW volume transport. This index shows the same cycles of variability as observed in temperature, NAO and AMO but without an obvious trend. © 2014 . Source

Goethel D.R.,University of Massachusetts Amherst | Legault C.M.,National Oceanic and Atmospheric Administration | Cadrin S.X.,University of Massachusetts Amherst
ICES Journal of Marine Science | Year: 2014

Ignoring population structure and connectivity in stock assessment models can introduce bias into important management metrics. Tag-integrated assessment models can account for spatially explicit population dynamics by modelling multiple population components, each with unique demographics, and estimating movement among them. A tagging submodel is included to calculate predicted tag recaptures, and observed tagging data are incorporated in the objective function to inform estimates of movement and mortality. We describe the tag-integrated assessment framework and demonstrate its use through an application to three stocks of yellowtail flounder (Limanda ferruginea) off New England. Movement among the three yellowtail flounder stocks has been proposed as a potential source of uncertainty in the closed population assessments of each. A tagging study was conducted during 2003-2006 with over 45 000 tagged fish released in the region, and the tagging data were included in the tag-integrated model. Results indicated that movement among stocks was low, estimates of stock size and fishing mortality were similar to those from conventional stock assessments, and incorporating stock connectivity did not resolve residual patterns. Despite low movement estimates, new interpretations of regional stock dynamics may have important implications for regional fisheries management given the source-sink nature of movement estimates. © 2014 © International Council for the Exploration of the Sea 2014. All rights reserved. Source

A new vertical discretization used in the atmospheric dynamics of the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) is illustrated, with enthalpy as the thermodynamic prognostic variable to reduce computation in thermodynamic equations while concerning all gas tracers in the model. Mass, energy, entropy, and angular momentum conservations are utilized as constraints to discretize the vertical integration with a finite-difference scheme. A specific definition of a generalized hybrid vertical coordinate, including sigma, isobaric, and isentropic surfaces, is introduced to define pressure at the model levels. Vertical fluxes are obtained by the equation of local changes in variables defined for vertical coordinates at all model layers. The forward-weighting semi-implicit time scheme is utilized to eliminate computational noise for stable integration. Because of time splitting between the dynamic and physics processes, the vertical advection is required both in the model dynamics and model physics, and the semi-implicit time scheme is used both in dynamics and after physics computation. Three configurations-sigma, sigma pressure, and sigma entropy-from the specific hybrid vertical coordinates with layer definition similar to NCEP operational GFS have been implemented in the NCEP GFS. Results from the sigma-isentropic coordinate show the largest anomaly correlation and the smallest root-mean-square error in tropical wind among all results at all layers, especially the upper layers. The scores from a period of daily forecast up to 5 days with the sigma-isentropic coordinate show the same level of skill as compared to the NCEP operational GFS. The results from the hurricane tracks for the fall of 2005 with sigma-isentropic coordinates show better scores compared with the operational GFS. © 2011 American Meteorological Society. Source

Karmalkar A.V.,University of Oxford | Bradley R.S.,University of Massachusetts Amherst | Diaz H.F.,National Oceanic and Atmospheric Administration
Climate Dynamics | Year: 2011

Central America has high biodiversity, it harbors high-value ecosystems and it's important to provide regional climate change information to assist in adaptation and mitigation work in the region. Here we study climate change projections for Central America and Mexico using a regional climate model. The model evaluation shows its success in simulating spatial and temporal variability of temperature and precipitation and also in capturing regional climate features such as the bimodal annual cycle of precipitation and the Caribbean low-level jet. A variety of climate regimes within the model domain are also better identified in the regional model simulation due to improved resolution of topographic features. Although, the model suffers from large precipitation biases, it shows improvements over the coarse-resolution driving model in simulating precipitation amounts. The model shows a dry bias in the wet season and a wet bias in the dry season suggesting that it's unable to capture the full range of precipitation variability. Projected warming under the A2 scenario is higher in the wet season than that in the dry season with the Yucatan Peninsula experiencing highest warming. A large reduction in precipitation in the wet season is projected for the region, whereas parts of Central America that receive a considerable amount of moisture in the form of orographic precipitation show significant decreases in precipitation in the dry season. Projected climatic changes can have detrimental impacts on biodiversity as they are spatially similar, but far greater in magnitude, than those observed during the El Niño events in recent decades that adversely affected species in the region. © 2011 Springer-Verlag. Source

Winton M.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2011

The sensitivity of Northern Hemisphere sea ice cover to global temperature change is examined in a group of climate models and in the satellite-era observations. The models are found to have well-defined, distinguishable sensitivities in climate change experiments. The satellite-era observations show a larger sensitivity-a larger decline per degree of warming-than any of the models. To evaluate the role of natural variability in this discrepancy, the sensitivity probability density function is constructed based upon the observed trends and natural variability of multidecadal ice cover and global temperature trends in a long control run of the GFDL Climate Model, version 2.1 (CM2.1). This comparison shows that the model sensitivities range from about 1 to more than 2 pseudostandard deviations of the variability smaller than observations indicate. The impact of natural Atlantic multidecadal temperature trends (as simulated by the GFDL model) on the sensitivity distribution is examined and found to be minimal. © 2011 American Meteorological Society. Source

Frankignoul C.,University Pierre and Marie Curie | Chael N.S.,University Pierre and Marie Curie | Kwon Y.-O.,Woods Hole Oceanographic Institution | Alexander M.A.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2011

The meridional shifts of the Oyashio Extension (OE) and of the Kuroshio Extension (KE), as derived from high-resolution monthly sea surface temperature (SST) anomalies in 1982-2008 and historical temperature profiles in 1979-2007, respectively, are shown based on lagged regression analysis to significantly influence the large-scale atmospheric circulation. The signals are independent from the ENSO teleconnections, which were removed by seasonally varying, asymmetric regression onto the first three principal components of the tropical Pacific SST anomalies. The response to the meridional shifts of the OE front is equivalent barotropic and broadly resembles the North Pacific Oscillation/western Pacific pattern in a positive phase for a northward frontal displacement. The response may reach 35 mat 250 hPa for a typicalOE shift, a strong sensitivity since the associated SST anomaly is 0.5 K. However, the amplitude, but not the pattern or statistical significance, strongly depends on the lag and an assumed 2-month atmospheric response time. The response is stronger during fall and winter and when the front is displaced southward. The response to the northward KE shifts primarily consists of a high centered in the northwestern North Pacific and hemispheric teleconnections. The response is also equivalent barotropic, except near Kamchatka, where it tilts slightly westward with height. The typical amplitude is half as large as that associated with OE shifts. © 2011 American Meteorological Society. Source

Quay P.D.,University of Washington | Peacock C.,National Oceanic and Atmospheric Administration | Bjrkman K.,University of Hawaii at Manoa | Karl D.M.,University of Hawaii at Manoa
Global Biogeochemical Cycles | Year: 2010

Primary production (PP) rates were estimated using concurrent 14C and 18O bottle incubations and a non-incubation oxygen isotope (17) based method during monthly cruises to the time series station ALOHA in the subtropical N. Pacific Ocean between March, 2006 and February, 2008. The mean gross oxygen production (GOP) rate in the photic layer (0-200m) at ALOHA was estimated at 103 ± 43 and 78 ± 17 mmol O2 m-2 d-1 from the 17 and 18O methods, respectively. In comparison, the mean 14C-PP rate (daytime incubations) in the photic layer was 42 ± 7 mmol C m -2 d-1 (502 ± 84 mg C m-2 d -1). Seasonal and depth variability (% change) for GOP rate was 2-3 times that for 14C-PP. The non-incubation 17-GOP rates consistently exceeded the incubation 18O-GOP rates by 25-60%, and possible methodological biases were evaluated. A supersaturation of the dissolved O2/Ar gas ratio was measured every month yielding a mean annual value of 101.3 ± 0.1% and indicating a consistent net autotrophic condition in the mixed layer at ALOHA. The mean annual net community production (NCP) rate at ALOHA estimated from dissolved O2/Ar gas ratio was 14 ± 4 mmol O2 m-2 d-1 (120 ± 33 mg C m-2 d-1 or 3.7 ± 1.0 mol C m-2 yr -1) for the mixed layer. A NCP/GOP ratio of 0.19 ± 0.08 determined from 17 and O2/Ar measurements indicated that ∼20% of gross photosynthetic production was available for export and harvest. © 2010 by the American Geophysical Union. Source

Overland J.E.,National Oceanic and Atmospheric Administration | Wang M.,University of Washington
Tellus, Series A: Dynamic Meteorology and Oceanography | Year: 2010

Recent loss of summer sea ice in the Arctic is directly connected to shifts in northern wind patterns in the following autumn, which has the potential of altering the heat budget at the cold end of the global heat engine. With continuing loss of summer sea ice to less than 20% of its climatological mean over the next decades, we anticipate increased modification of atmospheric circulation patterns. While a shift to a more meridional atmospheric climate pattern, the Arctic Dipole (AD), over the last decade contributed to recent reductions in summer Arctic sea ice extent, the increase in late summer open water area is, in turn, directly contributing to a modification of large scale atmospheric circulation patterns through the additional heat stored in the Arctic Ocean and released to the atmosphere during the autumn season. Extensive regions in the Arctic during late autumn beginning in 2002 have surface air temperature anomalies of greater than 3°C and temperature anomalies above 850 hPa of 1°C. These temperatures contribute to an increase in the 1000-500 hPa thickness field in every recent year with reduced sea ice cover. While gradients in this thickness field can be considered a baroclinic contribution to the flow field from loss of sea ice, atmospheric circulation also has a more variable barotropic contribution. Thus, reduction in sea ice has a direct connection to increased thickness fields in every year, but not necessarily to the sea level pressure (SLP) fields. Compositing wind fields for late autumn 2002-2008 helps to highlight the baroclinic contribution; for the years with diminished sea ice cover there were composite anomalous tropospheric easterly winds of ~1.4ms-1, relative to climatological easterly winds near the surface and upper tropospheric westerlies of ~3 ms-1. Loss of summer sea ice is supported by decadal shifts in atmospheric climate patterns. A persistent positive Arctic Oscillation pattern in late autumn (OND) during 1988-1994 and in winter (JFM) during 1989-1997 shifted to more interannual variability in the following years. An anomalous meridional wind pattern with high SLP on the North American side of the Arctic-the AD pattern, shifted from primarily small interannual variability to a persistent phase during spring (AMJ) beginning in 1997 (except for 2006) and extending to summer (JAS) beginning in 2005. © 2010 Blackwell Munksgaard. Source

Seidel D.J.,National Oceanic and Atmospheric Administration | Ao C.O.,Jet Propulsion Laboratory | Li K.,University of Maryland University College
Journal of Geophysical Research: Atmospheres | Year: 2010

Planetary boundary layer (PBL) processes control energy, water, and pollutant exchanges between the surface and free atmosphere. However, there is no observation-based global PBL climatology for evaluation of climate, weather, and air quality models or for characterizing PBL variability on large space and time scales. As groundwork for such a climatology, we compute PBL height by seven methods, using temperature, potential temperature, virtual potential temperature, relative humidity, specific humidity, and refractivity profiles from a 10 year, 505-station radiosonde data set. Six methods are directly compared; they generally yield PBL height estimates that differ by several hundred meters. Relative humidity and potential temperature gradient methods consistently give higher PBL heights, whereas the parcel (or mixing height) method yields significantly lower heights that show larger and more consistent diurnal and seasonal variations (with lower nighttime and wintertime PBLs). Seasonal and diurnal patterns are sometimes associated with local climatological phenomena, such as nighttime radiation inversions, the trade inversion, and tropical convection and associated cloudiness. Surface-based temperature inversions are a distinct type of PBL that is more common at night and in the morning than during midday and afternoon, in polar regions than in the tropics, and in winter than other seasons. PBL height estimates are sensitive to the vertical resolution of radiosonde data; standard sounding data yield higher PBL heights than high-resolution data. Several sources of both parametric and structural uncertainty in climatological PBL height values are estimated statistically; each can introduce uncertainties of a few 100 m. Copyright 2010 by the American Geophysical Union. Source

Cucurull L.,National Oceanic and Atmospheric Administration
Weather and Forecasting | Year: 2010

As of May 2007, the National Centers for Environmental Prediction (NCEP) implemented a new Global Data Assimilation System. This system incorporated the assimilation of global positioning system (GPS) radio occultation (RO) profiles from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) mission, which was launched in April 2006. Since then, this new type of observation has been shown to provide additional information on the thermodynamic state of the atmosphere, resulting in a significant increase in the model skill. Recent updates of the analysis and modeling codes have required a revision of the algorithm that assimilates GPS RO data. In addition, some modifications in the processing of the observations have further enhanced the need for a revisiting of the assimilation code. Better characterizations of the quality control procedures, observation error structure, and forward modeling for the GPS RO observations are described. The updated system significantly improves the data usage, in particular in the tropics. Different sets of the atmospheric refractive indices are also evaluated in this study. The model performance is proven to be quite sensitive to the chosen coefficients and a reevaluation of these constants is recommended within the GPS community. The new assimilation configuration results in an improvement in the anomaly correlation scores for the Southern Hemisphere extratropics (~4.5 h for the 500-mb geopotential heights at day 7) and a reduction of the high- and low-level tropical wind errors. Overall, the benefits of using COSMIC on top of all the other observations used in the operational system are still very significant. The loss in model skill when COSMIC is removed from the observing system is remarkable at day 4 (~8 h) and steadily increases beyond 12 h with the extended forecast range. © 2010 American Meteorological Society. Source

Toggweiler J.R.,National Oceanic and Atmospheric Administration | Lea D.W.,University of California at Santa Barbara
Paleoceanography | Year: 2010

The Earth became warmer and cooler during the ice ages along with changes in the Earth?s orbit, but the orbital changes themselves are not nearly large enough to explain the magnitude of the warming and cooling. Atmospheric CO 2 also rose and fell, but again, the CO2 changes are rather small in relation to the warming and cooling. So, how did the Earth manage to warm and cool by so much? Here we argue that, for the big transitions at least, the Earth did not warm and cool as a single entity. Rather, the south warmed instead at the expense of a cooler north through massive redistributions of heat that were set off by the orbital forcing. Oceanic CO2 was vented up to the atmosphere by the same redistributions. The north then warmed later in response to higher CO2 and a reduced albedo from smaller ice sheets. This form of northsouth displacement is actually very familiar, as it is readily observed during the Younger Dryas interval 13,000 years ago and in the various millennial-scale events over the last 90,000 years. © Copyright 2010 by the American Geophysical Union. Source

Park T.-W.,Seoul National University | Ho C.-H.,Seoul National University | Yang S.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2011

The present study reveals the changes in the characteristics of cold surges over East Asia associated with the Arctic Oscillation (AO). Based on circulation features, cold surges are grouped into two general types: wave train and blocking types. The blocking type of cold surge tends to occur during negative AO periods, that is, the AO-related polarity of the blocking type. However, the wave train type is observed during both positive and negative AO periods, although the wave train features associated with negative AO are relatively weaker. The cold surges during negative AO are stronger than those during positive AO in terms of both amplitude and duration. The cold surges during positive AO in which the extent of effect is confined to inland China passes through East Asia quickly because of weaker Siberian high and Aleutian low, leading to short duration of these cold surges. In contrast, the cold surge during negative AO, characterized by a well-organized anticyclone-cyclone couplet with high pressure over continental East Asia and low pressure over Japan, brings continuous cold air into the entire East Asian region for more than one week with long-lasting cold advection. It is also found that the tracks of the cold surges during negative AO tend to occur more frequently over Korea and Japan and less frequently over China, compared with those during positive AO. The tracks are related to a west-east dipole structure of the ratio of rain conversion to snow according to AO phase, resulting in freezing precipitation or snowfall events over inland China (Korea and Japan) are likely to occur more frequently during the positive (negative) AO periods. © 2011 American Meteorological Society. Source

Waples R.S.,National Oceanic and Atmospheric Administration | Luikart G.,University of Montana
Genetics | Year: 2014

Use of single-sample genetic methods to estimate effective population size has skyrocketed in recent years. Although the underlying models assume discrete generations, they are widely applied to age-structured species. We simulated genetic data for 21 iteroparous animal and plant species to evaluate two untested hypotheses regarding performance of the single-sample method based on linkage disequilibrium (LD): (1) estimates based on single-cohort samples reflect the effective number of breeders in one reproductive cycle (Nb), and (2) mixed-age samples reflect the effective size per generation (Ne). We calculated true Ne and Nb, using the model species' vital rates, and verified these with individual-based simulations. We show that single-cohort samples should be equally influenced by Nb and Ne and confirm this with simulated results: N̂b was a linear (r2 = 0.98) function of the harmonic mean of Ne and Nb. We provide a quantitative bias correction for raw Nb based on the ratio Nb/Ne, which can be estimated from two or three simple life history traits. Bias-adjusted estimates were within 5% of true Nb for all 21 study species and proved robust when challenged with new data. Mixed-age adult samples produced downwardly biased estimates in all species, which we attribute to a two-locus Wahlund effect (mixture LD) caused by combining parents from different cohorts in a single sample. Results from this study will facilitate interpretation of rapidly accumulating genetic estimates in terms of both Ne (which influences long-term evolutionary processes) and Nb (which is more important for understanding eco-evolutionary dynamics and mating systems). © 2014 by the Genetics Society of America. Source

Kasperski S.,National Oceanic and Atmospheric Administration
Marine Policy | Year: 2016

Current knowledge of the complex relationships within ecological and economic systems make operationalizing ecosystem approaches within fisheries management difficult. As these approaches are developed, it is important to include non-target species that affect the productivity (as prey) and availability (as predators) of targeted species. This study develops a multispecies bioeconomic model that incorporates ecological and economic interactions to determine the optimal harvest of each species in the presence of a "nuisance" species, which lowers the value of the fishery by negatively affecting the growth of the other species in the ecosystem, and has little harvest value of its own. The populations of walleye pollock, Pacific cod, and arrowtooth flounder (a nuisance species) in the Bering Sea/Aleutian Islands region of Alaska are used as a case study. Vessel-and gear-specific profit functions with multi-output production technologies are used, along with estimated multispecies stock dynamics equations, to determine the optimal multispecies quotas and subsidy on the harvest of the nuisance species to maximize the value of this fishery. Ignoring the nuisance species results in a substantially less productive and lower value fishery than optimal joint management. This study highlights the importance of incorporating the impact of non-targeted species in ecosystem-based fisheries management. © 2015. Source

Dessler A.E.,Texas A&M University | Davis S.M.,National Oceanic and Atmospheric Administration | Davis S.M.,University of Colorado at Boulder
Journal of Geophysical Research: Atmospheres | Year: 2010

A recent paper (Paltridge et al., 2009) found that specific humidity in the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis declined between 1973 and 2007, particularly in the tropical mid and upper troposphere, the region that plays the key role in the water vapor feedback. If borne out, this result suggests potential problems in the consensus view of a positive water vapor feedback. Here we consider whether this result holds in other reanalyses and what time scale of climate fluctuation is associated with the negative specific humidity trends. The five reanalyses analyzed here (the older NCEP/NCAR and ERA40 reanalyses and the more modern Japanese Reanalysis (JRA), Modern Era Retrospective-Analysis for Research and Applications (MERRA), and European Centre for Medium-Range Weather Forecasts (ECMWF)-interim reanalyses) unanimously agree that specific humidity generally increases in response to short-term climate variations (e.g., El Niño). In response to decadal climate fluctuations, the NCEP/NCAR reanalysis is unique in showing decreases in tropical mid and upper tropospheric specific humidity as the climate warms. All of the other reanalyses show that decadal warming is accompanied by increases in mid and upper tropospheric specific humidity. We conclude from this that it is doubtful that these negative long-term specific humidity trends in the NCEP/NCAR reanalysis are realistic for several reasons. First, the newer reanalyses include improvements specifically designed to increase the fidelity of long-term trends in their parameters, so the positive trends found there should be more reliable than in the older reanalyses. Second, all of the reanalyses except the NCEP/NCAR assimilate satellite radiances rather than being solely dependent on radiosonde humidity measurements to constrain upper tropospheric humidity. Third, the NCEP/NCAR reanalysis exhibits a large bias in tropical upper tropospheric specific humidity. And finally, we point out that there exists no theoretical support for having a positive short-term water vapor feedback and a negative long-term one. Copyright 2010 by the American Geophysical Union. Source

Wang C.,National Oceanic and Atmospheric Administration | Lee S.-K.,University of Miami | Mechoso C.R.,University of California at Los Angeles
Journal of Climate | Year: 2010

The Atlantic warm pool (AWP) is a large body of warm water comprising the Gulf of Mexico, Caribbean Sea, and western tropical North Atlantic. The AWP can vary on seasonal, interannual, and multidecadal time scales. The maximum AWP size is in the boreal late summer and early fall, with the largest extent in the year being about 3 times the smallest one. The AWP alternates with the Amazon basin in South America as the seasonal heating source for circulations of the Hadley and Walker type in the Western Hemisphere. During the boreal summer/fall, a strong Hadley-type circulation is established, with ascending motion over the AWP and subsidence over the southeastern tropical Pacific. This is accompanied by equatorward flow in the lower troposphere over the southeastern tropical Pacific, as dynamically required by the Sverdrup vorticity balance. It is shown by analyses of observational data and NCAR community atmospheric model simulations that an anomalously large (small) AWP during the boreal summer/fall results in a strengthening (weakening) of the Hadley-type circulation with enhanced descent (ascent) over the southeastern tropical Pacific. It is further demonstrated-by using a simple two-level model linearized about a specified background mean state-that the interhemispheric connection between the AWP and the southeastern tropical Pacific depends on the configuration of the background mean zonal winds in the Southern Hemisphere. © 2010 American Meteorological Society. Source

Munoz E.,University of Miami | Wang C.,National Oceanic and Atmospheric Administration | Enfield D.,University of Miami
Journal of Climate | Year: 2010

The influence of teleconnections on the Intra-Americas Sea (IAS; Gulf of Mexico and Caribbean Sea) has been mostly analyzed from the perspective of El Niño-Southern Oscillation (ENSO) on the Caribbean Sea (the latter being an extension of the tropical North Atlantic). This emphasis has overlooked both 1) the influence of other teleconnections on the IAS and 2) which teleconnections affect the Gulf of Mexico climate variability. In this study the different fingerprints that major teleconnection patterns have on the IAS during boreal spring are analyzed. Indices of teleconnection patterns are regressed and correlated to observations of oceanic temperature and atmospheric data from reanalyses and observational datasets. It is found that the Pacific teleconnection patterns that influence the IAS SSTs do so by affecting the Gulf of Mexico in an opposite manner to the Caribbean Sea. These analyzed Pacific climate patterns are the Pacific-North American (PNA) teleconnection, the Pacific decadal oscillation (PDO), and ENSO. The North Atlantic Oscillation (NAO) is related to a lesser degree with the north-south SST anomaly dipole than are Pacific teleconnection patterns. It is also found that the IAS influence from the midlatitude Pacific mostly affects the Gulf of Mexico, whereas the influence from the tropical Pacific mostly affects the Caribbean Sea. Therefore, the combination of a warm ENSO event and a positive PNA event induces a strong IAS SST anomaly dipole between the Gulf of Mexico and the Caribbean Sea during spring. By calculating an index that represents the IAS SST anomaly dipole, it is found that the dipole forms mostly in response to changes in the air-sea heat fluxes. In the Gulf of Mexico the dominant mechanisms are the air-sea differences in humidity and temperature. The changes in shortwave radiation also contribute to the dipole of net air-sea heat flux. The changes in shortwave radiation arise, in part, by the cloudiness triggered by the air-sea differences in humidity, and also by the changes in the convection cell that connects the Amazon basin to the IAS. Weaker Amazon convection (e.g., in the event of a warm ENSO event) reduces the subsidence over the IAS, and henceforth the IAS cloudiness increases (and the shortwave radiation decreases). This study contributes to a greater understanding of how the IAS is influenced by different Pacific and Atlantic teleconnections. © 2010 American Meteorological Society. Source

Barnes E.A.,University of Washington | Hartmann D.L.,University of Washington | Frierson D.M.W.,University of Washington | Kidston J.,National Oceanic and Atmospheric Administration
Geophysical Research Letters | Year: 2010

An asymmetry in the persistence of the eddy-driven jet is demonstrated, whereby the equatorward-shifted (low-phase) jet is more persistent than the poleward-shifted (high-phase) jet. The asymmetry is investigated by stirring the non-divergent vorticity equation on the sphere and is shown to arise due to the sphericity of the earth, which inhibits poleward wave breaking when the jet is at high latitudes. This spherical effect becomes increasingly important as the mean jet is positioned at higher latitudes. The persistence of the annular mode decreases as the mean jet moves closer to the pole due to the decreased persistence of the high-phase state, while the low-phase state exhibits similar persistence regardless of the jet position. These results suggest that with the expected poleward shift of the jet due to increasing greenhouse gases, the annular mode's total persistence will decrease due to a decrease in the persistence of the high-phase. Copyright © 2010 by the American Geophysical Union. Source

Wang C.,National Oceanic and Atmospheric Administration | Dong S.,University of Miami | Munoz E.,University of Miami
Climate Dynamics | Year: 2010

Seawater property changes in the North Atlantic Ocean affect the Atlantic meridional overturning circulation (AMOC), which transports warm water northward from the upper ocean and contributes to the temperate climate of Europe, as well as influences climate globally. Previous observational studies have focused on salinity and freshwater variability in the sinking region of the North Atlantic, since it is believed that a freshening North Atlantic basin can slow down or halt the flow of the AMOC. Here we use available data to show the importance of how density patterns over the upper ocean of the North Atlantic affect the strength of the AMOC. For the long-term trend, the upper ocean of the subpolar North Atlantic is becoming cooler and fresher, whereas the subtropical North Atlantic is becoming warmer and saltier. On a multidecadal timescale, the upper ocean of the North Atlantic has generally been warmer and saltier since 1995. The heat and salt content in the subpolar North Atlantic lags that in the subtropical North Atlantic by about 8-9 years, suggesting a lower latitude origin for the temperature and salinity anomalies. Because of the opposite effects of temperature and salinity on density for both long-term trend and multidecadal timescales, these variations do not result in a density reduction in the subpolar North Atlantic for slowing down the AMOC. Indeed, the variations in the meridional density gradient between the subpolar and subtropical North Atlantic Ocean suggest that the AMOC has become stronger over the past five decades. These observed results are supported by and consistent with some oceanic reanalysis products. © 2009 Springer-Verlag. Source

Averyt K.,National Oceanic and Atmospheric Administration
Bulletin of the American Meteorological Society | Year: 2010

The climate scientists need to be provided with the tools required to address the multifaceted challenges posed by climate change. Climate scientists should not assume that those who need climate information for planning purposes are exposed to the relevant science. Stakeholders need to be included in the scientific process and connections need to be made across disciplinary areas in order to enhance decision-making with the use of climate science. The culture of the academic climate-science community fails to teach the younger generation of postgraduate students to work with decision-makers in order to develop successful applied science strategies, and it fails to reward junior faculty members for focusing on multidisciplinary, user-involved climate science. Several programs that offer training for young scientists in communicating with decision makers, includes the American Association for the Advancement of Science Policy Fellowships, NOAA Knauss Sea Grant Fellowships, and Aldo Leopold Fellowships. Source

Kossin J.P.,National Oceanic and Atmospheric Administration | Camargo S.J.,Lamont Doherty Earth Observatory | Sitkowski M.,University of Wisconsin - Madison
Journal of Climate | Year: 2010

The variability of North Atlantic tropical storm and hurricane tracks, and its relationship to climate variability, is explored. Tracks from the North Atlantic hurricane database for the period 1950-2007 are objectively separated into four groups using a cluster technique that has been previously applied to tropical cyclones in other ocean basins. The four clusters form zonal and meridional separations of the tracks. The meridional separation largely captures the separation between tropical and more baroclinic systems, while the zonal separation segregates Gulf of Mexico and Cape Verde storms. General climatologies of the seasonality, intensity, landfall probability, and historical destructiveness of each cluster are documented, and relationships between cluster membership and climate variability across a broad spectrum of time scales are identified. Composites, with respect to cluster membership, of sea surface temperature and other environmental fields show that regional and remote modes of climate variability modulate the cluster members in substantially differing ways and further demonstrate that factors such as El Niño-Southern Oscillation (ENSO), Atlantic meridional mode (AMM), North Atlantic Oscillation (NAO), and Madden-Julian oscillation (MJO) have varying intrabasin influences on North Atlantic tropical storms and hurricanes. Relationships with African easterly waves are also considered. The AMM and ENSO are found to most strongly modulate the deep tropical systems, while the MJO most strongly modulates Gulf of Mexico storms and the NAO most strongly modulates storms that form to the north and west of their Cape Verde counterparts and closer to the NAO centers of action. Different clusters also contribute differently to the observed trends in North Atlantic storm frequency and may be related to intrabasin differences in sea surface temperature trends. Frequency trends are dominated by the deep tropical systems, which account for most of the major hurricanes and overall power dissipation. Contrarily, there are no discernable trends in the frequency of Gulf of Mexico storms, which account for the majority of landfalling storms. When the proportion that each cluster contributes to overall frequency is considered, there are clear shifts between the deep tropical systems and the more baroclinic systems. A shift toward proportionally more deep tropical systems began in the early to mid-1980s more than 10 years before the 1995 North Atlantic hurricane season, which is generally used to mark the beginning of the present period of heightened activity. © 2010 American Meteorological Society. Source

Wang X.,University of Wisconsin - Madison | Key J.R.,National Oceanic and Atmospheric Administration | Liu Y.,University of Wisconsin - Madison
Journal of Geophysical Research: Oceans | Year: 2010

Sea ice is a very important indicator and an effective modulator of regional and global climate change. Current remote sensing techniques provide an unprecedented opportunity to monitor the cryosphere routinely with relatively high spatial and temporal resolutions. In this paper, we introduce a thermodynamic model to estimate sea and lake ice thickness with optical (visible, near-infrared, and infrared) satellite data. Comparisons of nighttime ice thickness retrievals to ice thickness measurements from upward looking submarine sonar show that this thermodynamic model is capable of retrieving ice thickness up to 2.8 m. The mean absolute error is 0.18 m for samples with a mean ice thickness of 1.62 m, i.e., an 11% mean absolute error. Comparisons with in situ Canadian stations and moored upward looking sonar measurements show similar results. Sensitivity studies indicate that the largest errors come from uncertainties in surface albedo and downward solar radiation flux estimates from satellite data, followed by uncertainties in snow depth and cloud fractional coverage. Due to the relatively large uncertainties in current satellite retrievals of surface albedo and surface downward shortwave radiation flux, the current model is not recommended for use with daytime data. For nighttime data, the model is capable of resolving regional and seasonal variations in ice thickness and is useful for climatological analysis. © 2010 by the American Geophysical Union. Source

Lengaigne M.,Institute Of Rechrche Pour Le Developpement Laboratoire Doceanographie Et Of Climatologie | Vecchi G.A.,National Oceanic and Atmospheric Administration
Climate Dynamics | Year: 2010

As in the observed record, the termination of El Niño in the coupled IPCC-AR4 climate models involves meridional processes tied to the seasonal cycle. These meridional processes both precondition the termination of El Niño events in general and lead to a peculiar termination of extreme El Niño events (such as those of 1982-83 and 1997-98), in which the eastern equatorial Pacific warm sea surface temperature anomalies (SSTA) persist well into boreal spring/early-summer. The mechanisms controlling the peculiar termination of extreme El Niño events, which involves to the development of an equatorially centred intertropical convergence zone, are consistent across the four models that exhibit extreme El Niños and observational record, suggesting that this peculiar termination represents a general feature of extreme El Niños. Further, due to their unusual termination, extreme El Niños exhibit an apparent eastward propagation of their SSTA, which can strongly influence estimates of the apparent propagation of ENSO over multi-decadal periods. Interpreting these propagation changes as evidence of changes in the underlying dynamical feedbacks behind El Niño could therefore be misleading, given the strong influence of a single extreme event. © 2009 Springer-Verlag. Source

Hu H.,Michigan State University | Wang J.,National Oceanic and Atmospheric Administration
Journal of Geophysical Research: Oceans | Year: 2010

Ocean circulation and the tidal current in the Bering Sea are simulated simultaneously using a coupled ice-ocean model (CIOM) with tidal and parameterized wave mixing to investigate several important physical processes. The simulated circulation pattern in the deep basin is relatively stable, cyclonic, and has little seasonal change. The Bering Slope Current is estimated at 5 Sv and the Kamchatka Current at 20 Sv. The modeled volume transports through the Aleutian passes compared reasonably well with observations. It is confirmed that subtidal clockwise circulation around St. George and St. Paul islands are driven by tidal rectification. The simulation results show that wind-wave mixing and tidal stirring are the main factors controlling the formation of the upper and the bottom mixed layers, respectively. The mechanism of thermocline and the cold pool (summer minimum-temperature water) formation in the middle shelf are investigated in depth. The CIOM reproduces the cold winter-convective water in the middle shelf that forms the bottom cold pool, which persists throughout the summer until sea surface cooling and strong wind mixing in fall, leading to an unstable vertical water column and eventually to vertically well-mixed water in the winter. Sensitivity experiments show that tidal and wind-wave mixing are two important factors in accurately estimating the volume of the cold pool, which is the ideal marine habitat for cold water species. Copyright 2010 by the American Geophysical Union. Source

Zhang R.,National Oceanic and Atmospheric Administration
Geophysical Research Letters | Year: 2010

Extensive modeling studies show that changes in the anthropogenic forcing due to increasing greenhouse gases might lead to a slowdown of the Atlantic meridional overturning circulation (AMOC) in the 21st century, but the AMOC weakening estimated in most previous modeling studies is in depth space. Using a coupled ocean atmosphere model (GFDL CM2.1), this paper shows that in density space, the anthropogenically forced AMOC changes over the 21st century are intensified at northern high latitudes (nearly twice of those at lower latitudes) due to changes in the North Atlantic Deep Water (NADW) formation. In contrast, anthropogenically forced AMOC changes are much smaller in depth space at the same northern high latitudes. Hence projecting AMOC changes in depth space would lead to a significant underestimation of AMOC changes associated with changes in the NADW formation. The result suggests that monitoring AMOC changes at northern high latitudes in density space might reveal much larger signals than those at lower latitudes. The simulated AMOC changes in density space under anthropogenic forcing can not be distinguished from that induced by natural AMOC variability for at least the first 20 years of the 21st century, although the signal can be detected over a much longer period. © 2010 by the American Geophysical Union. Source

Grodsky S.A.,University of Maryland University College | Lumpkin R.,National Oceanic and Atmospheric Administration | Carton J.A.,University of Maryland University College
Geophysical Research Letters | Year: 2011

The Global Drifter Program (GDP) has been measuring near-surface ocean currents with surface drifters since 1979. At least half of the World Ocean now has drifter velocity time series longer than 15 years. The availability of this data opens new opportunities to explore observationally how ocean circulation responds to changing surface forcing. In this paper we report evidence of an apparently spurious acceleration of global surface drifter currents. This rapid acceleration occurs in a pattern reflecting the geographic distribution of mean surface winds. For example, in the westerly wind region of the Southern Ocean this strengthening is at least 0.5 cm/s per year eastward, while in the easterly trade wind region of the tropics this strengthening is on average 0.25 cm/s per year westward. One possible explanation we explore is that the bias is due to the presence of some undrogued drifters whose frequency of occurrence changes in time and whose windage is significantly greater than that of the drogued drifters. This paper is dedicated to the memory of Professor Peter Niiler, who first suggested this explanation. Copyright 2011 by the American Geophysical Union. Source

Wang H.,Pacific Northwest National Laboratory | Rasch P.J.,Pacific Northwest National Laboratory | Feingold G.,National Oceanic and Atmospheric Administration
Atmospheric Chemistry and Physics | Year: 2011

We use a cloud-system-resolving model to study marine-cloud brightening. We examine how injected aerosol particles that act as cloud condensation nuclei (CCN) are transported within the marine boundary layer and how the additional particles in clouds impact cloud microphysical processes, and feedback on dynamics. Results show that the effectiveness of cloud brightening depends strongly on meteorological and background aerosol conditions. Cloud albedo enhancement is very effective in a weakly precipitating boundary layer and in CCN-limited conditions preceded by heavy and/or persistent precipitation. The additional CCN help sustain cloud water by weakening the precipitation substantially in the former case and preventing the boundary layer from collapse in the latter. For a given amount of injected CCN, the injection method (i.e., number and distribution of sprayers) is critical to the spatial distribution of these CCN. Both the areal coverage and the number concentration of injected particles are key players but neither one always emerges as more important than the other. The same amount of injected material is much less effective in either strongly precipitating clouds or polluted clouds, and it is ineffective in a relatively dry boundary layer that supports clouds of low liquid water path. In the polluted case and "dry" case, the CCN injection increases drop number concentration but lowers supersaturation and liquid water path. As a result, the cloud experiences very weak albedo enhancement, regardless of the injection method. © 2011 Author(s). Source

Lee S.S.,National Oceanic and Atmospheric Administration | Lee S.S.,University of Colorado at Boulder
Atmospheric Chemistry and Physics | Year: 2011

This study examines the dependence of aerosol-precipitation interactions on environmental humidity in a mesoscale cloud ensemble (MCE) which is composed of convective and stratiform clouds. The author found that increases in aerosol concentration enhance evaporative cooling, which raises not only the intensity of vorticity and entrainment but also that of downdrafts and low-level convergence. The increase in vorticity tends to suppress precipitation. The increase in low-level convergence tends to enhance precipitation by generating more secondary clouds in a muptiple-cloud system simulated here. At high humidity, the effect of the increased vorticity on cloud-liquid mass and, thus, precipitation is outweighed by that of the increased low-level convergence. This leads to the precipitation enhancement induced by the increase in aerosol concentration. When humidity lowers to mid humidity, the effect of aerosol on low-level convergence still dominates that on entrainment, leading to the precipitation enhancement with the increased aerosol concentration. With the lowest humidity in the current work, the effect of aerosol on entrainment dominates that on low-level convergence, leading to the precipitation suppression with the increased aerosol concentration. Hence, there is not only a competition between the effect of evaporation on vorticity and that on low-level convergence at a given humidity level but also the variation of the competition with the varying humidity. This competition and variation are absent in a single-cloud system where the effect of low-level convergence on secondary clouds is absent. This exemplifies a difference in the mechanism which controls aerosol-precipitation interactions between a single-cloud system and a multiple-cloud system. © 2011 Author(s). Source

Matrosov S.Y.,University of Colorado at Boulder | Matrosov S.Y.,National Oceanic and Atmospheric Administration
Journal of Geophysical Research: Atmospheres | Year: 2011

Measurements from ground-based collocated Ka- and W-band vertically pointing Doppler radars were used to evaluate the differential Doppler velocity (DDV) approach for retrieving a size parameter of the aggregate particle distributions in ice clouds. This approach was compared to a more traditional method based on the dual-frequency reflectivity ratio (DFR) using case study observations in different clouds. Because of measurement errors and other uncertainties, meaningful DDV-based retrievals were generally available for the size slope parameter interval of 9 cm-1 < Λ < 25 cm-1. The DFR were generally available for particle populations with Λ up to about 45 cm-1. Expected retrieval errors in Λ the interval between 9 cm-1 and 25 cm-1 were about 40% for the DFR-based estimates and about a factor of 2 larger for the DDV method. Errors increase for noisier measurements. Comparisons of the DDV- and DFR- inferred values of Λ when both retrievals were available revealed their general consistency with a relative standard deviation between results being within retrieval uncertainties. While the DFR approach appears to be more accurate, it requires a 0 dB constraint near cloud tops, which mitigates uncertainties in absolute radar calibrations and differing attenuation paths. The DDV approach generally does not require such a constraint if radar beams are perfectly aligned in vertical (which might not be exactly a case during some observations). Given this, DDV measurements may potentially allow ice particle sizing in situations when DFR constraining is not effective or available (e.g., in precipitating clouds and in clouds with substantial amounts of supercooled water). Copyright 2011 by the American Geophysical Union. Source

Novak D.R.,National Oceanic and Atmospheric Administration | Colle B.A.,State University of New York at Stony Brook
Weather and Forecasting | Year: 2012

The forecast uncertainty of mesoscale snowband formation and evolution is compared using predictions from a 16-member multimodel ensemble at 12-km grid spacing for the 25 December 2002, 12 February 2006, and 14 February 2007 northeast U.S. snowstorms. Using these predictions, the case-to-case variability in the predictability of band formation and evolution is demonstrated. Feature-based uncertainty information is also presented as an example of what may be operationally feasible from postprocessing information from future short-range ensemble forecast systems. Additionally, the initial condition sensitivity of band location in each case is explored by contrasting the forecast evolutions of initial condition members with large differences in snowband positions. Considerable uncertainty in the occurrence, and especially timing and location, of band formation and subsequent evolution was found, even at forecast projections <24 h. The ensemble provided quantitative mesoscale band uncertainty information, and differentiated between high-predictability (14 February 2007) and low-predictability (12 February 2006) cases. Among the three cases, large (small) initial differences in the upper-level PV distribution and surface mean sea level pressure of the incipient cyclone were associated with large (small) differences in forecast snowband locations, suggesting that case-to-case differences in predictability may be related to the quality of the initial conditions. The complexity of the initial flow may also be a discriminator. Error growth was evident in each case, consistent with previous mesoscale predictability research, but predictability differences were not correlated to the degree of convection. Discussion of these results and future extensions of the work are presented. © 2012 American Meteorological Society. Source

Jones T.A.,University of Oklahoma | Stensrud D.J.,National Oceanic and Atmospheric Administration
Weather and Forecasting | Year: 2012

One satellite data product that has received great interest in the numerical weather prediction community is the temperature and mixing ratio profiles derived from the Atmospheric Infrared Sounder (AIRS) instrument on board the Aqua satellite. This research assesses the impact of assimilating AIRS profiles on high-resolution ensemble forecasts of southern plains severe weather events occurring on 26 May 2009 and 10 May 2010 by comparing two ensemble forecasts. In one ensemble, the 1830 and 2000 UTC level 2 AIRS temperature and dewpoint profiles are assimilated with all other routine observations into a 36-member, 15-km Weather and Research Forecast Model (WRF) ensemble using a Kalman filter approach. The other ensemble is identical, except that only routine observations are assimilated. In addition, 3-km one-way nested-grid ensemble forecasts are produced during the periods of convection. Results indicate that over the contiguous United States, the AIRS profiles do not measurably improve the ensemble mean forecasts of midtropospheric temperature and dewpoint. However, the ensemble mean dewpoint profiles in the region of severe convective development are improved by the AIRS assimilation. Comparisons of the forecast ensemble radar reflectivity probabilities between the 1- and 4-h forecast times with nearby Weather Surveillance Radar-1988 Doppler (WSR-88D) observations show that AIRS-enhanced ensembles consistently generate more skillful forecasts of the convective features at these times. © 2012 American Meteorological Society. Source

Coniglio M.C.,National Oceanic and Atmospheric Administration
Weather and Forecasting | Year: 2012

This study uses radiosonde observations obtained during the second phase of the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) to verify base-state variables and severe-weather-related parameters calculated from Rapid Update Cycle (RUC) analyses and 1-h forecasts, as well as those calculated from the operational surface objective analysis system used at the Storm Prediction Center (the SFCOA). The rapid growth in temperature, humidity, and wind errors from 0 to 1 h seen at all levels in a past RUC verification study by Benjamin et al. is not seen in the present study. This could be because the verification observations are also assimilated into the RUC in the Benjamin et al. study, whereas the verification observations in the present study are not. In the upper troposphere, the present study shows large errors in relative humidity, mostly related to a large moist bias. The planetary boundary layer tends to be too shallow in the RUC analyses and 1-h forecasts. Wind speeds tend to be too fast in the lowest 1 km and too slow in the 2- 4-km layer. RUC and SFCOA 1-h forecast errors for many important severe weather parameters are large relative to their potential impact on convective evolution. However, the SFCOA significantly improves upon the biases seen in most of the 1-h RUC forecasts for the base-state surface variables and most of the other severe-weather-related parameters, indicating that the SFCOA has a more significant impact in reducing the biases in the 1-h RUC forecasts than on the root-mean-squared errors. © 2012 American Meteorological Society. Source

Grell G.,National Oceanic and Atmospheric Administration | Freitas S.R.,National Institute for Space Research | Stuefer M.,University of Alaska Fairbanks | Fast J.,Pacific Northwest National Laboratory
Atmospheric Chemistry and Physics | Year: 2011

A plume rise algorithm for wildfires was included in WRF-Chem, and applied to look at the impact of intense wildfires during the 2004 Alaska wildfire season on weather simulations using model resolutions of 10 km and 2 km. Biomass burning emissions were estimated using a biomass burning emissions model. In addition, a 1-D, time-dependent cloud model was used online in WRF-Chem to estimate injection heights as well as the vertical distribution of the emission rates. It was shown that with the inclusion of the intense wildfires of the 2004 fire season in the model simulations, the interaction of the aerosols with the atmospheric radiation led to significant modifications of vertical profiles of temperature and moisture in cloud-free areas. On the other hand, when clouds were present, the high concentrations of fine aerosol (PM2.5) and the resulting large numbers of Cloud Condensation Nuclei (CCN) had a strong impact on clouds and cloud microphysics, with decreased precipitation coverage and precipitation amounts during the first 12 h of the integration. During the afternoon, storms were of convective nature and appeared significantly stronger, probably as a result of both the interaction of aerosols with radiation (through an increase in CAPE) as well as the interaction with cloud microphysics. © 2011 Author(s). Source

Seung C.K.,National Oceanic and Atmospheric Administration
Marine Policy | Year: 2016

Alaska fisheries have strong spillover effects on economies of other states (especially the state of Washington) due to their dependence on imports from these other states. Several studies attempt to develop inter-regional or multi-regional economic impact models to investigate these spillover effects, and calculate the multipliers for Alaska fisheries. However, these multipliers measure only total economic impacts, failing to provide fishery managers with the information on how and along what channels these total economic impacts are generated and transmitted throughout the regions. This paper uses an inter-regional structural path analysis (IRSPA) to identify the various channels (paths) through which the economic impacts of an initial shock to a seafood sector are transmitted, amplified, and spilled over to other regions, within an inter-regional social accounting matrix (IRSAM) framework for two US regions - Alaska and the rest of US (RUS). © 2016 . Source

Matrosov S.Y.,University of Colorado at Boulder | Matrosov S.Y.,National Oceanic and Atmospheric Administration
Journal of Applied Meteorology and Climatology | Year: 2015

An approach is described to retrieve the total amount of ice in a vertical atmospheric column in precipitating clouds observed by the operational Weather Surveillance Radar-1988 Doppler (WSR-88D) systems. This amount expressed as ice water path (IWP) is retrieved using measurements obtained during standard WSR-88D scanning procedures performed when observing precipitation. WSR-88D-based IWP estimates are evaluated using dedicated cloud microphysical retrievals available from the CloudSat and auxiliary spaceborne measurements. The evaluation is performed using measurements obtained in extensive predominantly stratiform precipitation systems containing both ice hydrometeors aloft and rain near the ground. The analysis is based on retrievals of IWP from satellite and the ground-based KWGX and KSHV WSR-88D that are closely collocated in time and space. The comparison results indicate a relatively high correlation between satellite and WSR-88D IWP retrievals, with corresponding correlation coefficients of around 0.7. The mean relative differences between spaceborne and ground-based estimates are around 50%-60%, which is on the order of IWP retrieval uncertainties and is comparable to the differences among various operational CloudSat IWP products. The analysis performed in this study suggests that the quantitative information on ice content of precipitation systems can generally be obtained from operational WSR-88D measurements, when they perform routine scans to observe precipitation. The limitations of WSR-88D IWP estimates due to radar beam tilt restrictions and the overshooting effects due to Earth's sphericity are discussed. © 2015 American Meteorological Society. Source

Zhao X.,Chinese Academy of Sciences | Dryer M.,National Oceanic and Atmospheric Administration
Space Weather | Year: 2014

One of the major solar transients, coronal mass ejections (CMEs) and their related interplanetary shocks have severe space weather effects and become the focus of study for both solar and space scientists. Predicting their evolutions in the heliosphere and arrival times at Earth is an important component of the space weather predictions. Various kinds of models in this aspect have been developed during the past decades. In this paper, we will present a view of the present status (during Solar Cycle 24 in 2014) of the space weather's objective to predict the arrival of coronal mass ejections and their interplanetary shock waves at Earth. This status, by implication, is relevant to their arrival elsewhere in the solar system. Application of this prediction status is clearly appropriate for operational magnetospheric and ionospheric situations including A - > B - > Csolar system missions. We review current empirical models, expansion speed model, drag-based models, physics-based models (and their real-time prediction's statistical experience in Solar Cycle 23), and MHD models. New observations in Solar Cycle 24, including techniques/models, are introduced as they could be incorporated to form new prediction models. The limitations of the present models and the direction of further development are also suggested. © 2014. American Geophysical Union. All Rights Reserved. Source

Stoner A.W.,National Oceanic and Atmospheric Administration
Fisheries Research | Year: 2012

Evaluating vitality and predicting mortality in commercially exploited crustaceans is increasingly important for reducing discard mortality and for improving handling and shipping for live markets. A suite of 10 reflex actions were identified in spot prawns (Pandalus platyceros) that vary in sensitivity to injury and type of stressor. After establishing a baseline for stereotypic reflexes, prawns were subjected to physiological stress (emersion up to 60. min) and physical trauma (dropping). The prawns were tolerant of air exposure up to 40. min, but susceptible to injuries from dropping and the results within treatments were variable. However, mortality of individuals over a 30-day recovery period was closely related to a simple reflex impairment score calculated as the sum of reflexes lost (range = 0-10) and the effects of different injuries were additive. Logistic regression indicated that reflex impairment was an excellent predictor of delayed mortality (87.5% correct predictions) across prawn size (35-48. mm carapace length) and treatment types. A sigmoid curve describing the relationship between impairment and mortality was termed a Reflex Action Mortality Predictor. This RAMP approach should be a valuable tool in practical experiments related to both discard mortality and handling live crustaceans without the need for tagging or long-term holding. © 2012. Source

Doyle M.J.,University of Washington | Mier K.L.,National Oceanic and Atmospheric Administration
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2012

For Gulf of Alaska (GOA) fish populations, ordination by principal component analysis of a matrix of species by early life history and ecological traits resulted in distribution of species along three primary gradients. These are synonymous with phenology of egg and larval production, quantity of production, and ubiquity of larvae, the latter representing temporal and spatial extent of distribution in the pelagic environment. GOA species were assigned to categories that shared similar positions in ordination space relative to the three primary gradients. From this comparative analysis, a conceptual framework is proposed for species' early life histories representing trade-offs in adaptation to prevailing environmental conditions and associated vulnerability and resilience factors that may modulate species' recruitment responses to environmental variability. The utility of this framework for evaluating response to environmental forcing was supported by the analysis of a 27-year time series of GOA late spring larval fish abundance. The hypothesis for this ongoing research is that we can utilize similarities in reproductive and early life history characteristics among species to identify (i) ecologically determined species groups that are predisposed to respond to environmental forcing in similar ways and (ii) plausible environmental predictors of recruitment variation attributable to aspects of early life history. Source

Smith W.L.,University of Kansas | Busby M.S.,National Oceanic and Atmospheric Administration
Molecular Phylogenetics and Evolution | Year: 2014

Despite recent progress on the higher-level relationships of the Cottoidei and its familial components, phylogenetic conflict and uncertainty remain within the Cottoidea. We analyzed a dataset composed of 4518 molecular (mitochondrial 12S, tRNA-Val, 16S, and cytochrome b and nuclear TMO-4c4, Histone H3, and 28S) and 72 morphological characters for 69 terminals to address cottoid intrarelationships. The resulting well-resolved phylogeny was used to produce a revised taxonomy that is consistent with the available molecular and morphological data and recognizes six families: Agonidae, Cottidae, Jordaniidae, Psychrolutidae, Rhamphocottidae, and Scorpaenichthyidae. The traditional Agonidae was expanded to include traditional hemitripterids and Hemilepidotus. The traditional Cottidae was restricted to Leptocottus, Trachidermus, and the riverine, lacustrine, and Lake Baikal freshwater cottoids. Jordaniidae (Jordania and Paricelinus) was separated from the traditional cottids; Psychrolutidae was expanded from the traditional grouping to include nearly all traditional marine cottids and the single species of bathylutichthyid. Rhamphocottidae was expanded to include the traditional ereuniids, and Scorpaenichthyidae separated Scorpaenichthys from the traditional cottids. The importance of early-life-history characters to the resulting phylogeny and taxonomy were highlighted. © 2014 Elsevier Inc. Source

Baranyi T.,Hungarian Academy of Sciences | Kiraly S.,Hungarian Academy of Sciences | Coffey H.E.,National Oceanic and Atmospheric Administration
Monthly Notices of the Royal Astronomical Society | Year: 2013

Sunspot area data play an important role in the studies of solar activity and its long-term variations. In order to reveal real long-term solar variations precise homogeneous sunspot area data bases should be used. However, the measured areas may be burdened with systematic deviations, which may vary in time. Thus, there is a need to investigate the long-term variation of sunspot area data sets and to determine the time-dependent cross-calibration factors. In this study, we investigate the time-dependent differences between the available long-term sunspot data bases. Using the results, we estimate the correction factor to calibrate the corrected daily sunspot areas of Debrecen Photoheliographic Data (DPD) to the same data of Greenwich Photoheliographic Results (GPR) by using the overlapping Kislovodsk and Pulkovo data. We give the correction factor as GPR = 1.08(±0.11)DPD. ©2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Source

Lefohn A.S.,A.S.L. and Associates | Oltmans S.J.,National Oceanic and Atmospheric Administration
Atmospheric Environment | Year: 2010

In this analysis, we characterize urban and rural ozone (O 3) trends across the US for the periods 1980-2008 (29 years) and 1994-2008 (15 years) using three exposure metrics, which summarize daily O 3 concentrations to reflect different ways O 3 may affect human health and vegetation. We observe that a statistically significant trend at a specific monitoring site, using one exposure metric, does not necessarily result in a similar trend using the other two metrics. The two most common trends among the monitoring sites are either a continuation of negative trending over the 29-year period or a shift from negative to no trend status, indicating a leveling off of the trending. Very few sites exhibit statistically significant increases in the exposure indices. In characterizing the statistically significant changes in the distribution of hourly average O 3, we observe subtle statistically significant changes in the lower part of the distribution (i.e., below 50ppb) that are not necessarily captured by the trending patterns associated with the three exposure metrics. Using multisite data from 12 metropolitan cities, we find that as the frequency of higher hourly average concentrations is reduced, the lower hourly average concentrations also move upward toward the mid-level values. The change in the number of the hourly average concentrations in the lower range is consistent with decreased NO scavenging. We recommend assessing possible subtle shifts in O 3 concentrations by characterizing changes in the distribution of hourly average concentrations by month. Identifying statistically significant monthly changes in the mid- and low-level hourly average concentrations may provide important information for assessing changes in physical processes associated with global climate change, long-range transport, and the efficacy of models used for emission and risk reductions. Our results indicate that it is important to investigate the change in the trending pattern with time (e.g., moving 15-year trending) in order to assess how year-to-year variability may influence the trend calculation. © 2010 Elsevier Ltd. Source

Zhou B.,ENVIRON International Corporation | Du J.,National Oceanic and Atmospheric Administration
Weather and Forecasting | Year: 2010

A new multivariable-based diagnostic fog-forecasting method has been developed at NCEP. The selection of these variables, their thresholds, and the influences on fog forecasting are discussed. With the inclusion of the algorithm in the model postprocessor, the fog forecast can now be provided centrally as direct NWP model guidance. The method can be easily adapted to other NWP models. Currently, knowledge of how well fog forecasts based on operational NWP models perform is lacking. To verify the new method and assess fog forecast skill, as well as to account for forecast uncertainty, this fog-forecasting algorithm is applied to a multimodel-based Mesoscale Ensemble Prediction System (MEPS). MEPS consists of 10 members using two regional models [the NCEP Nonhydrostatic Mesoscale Model (NMM) version of the Weather Research and Forecasting (WRF) model and the NCAR Advanced Research version of WRF (ARW)] with 15-km horizontal resolution. Each model has five members (one control and four perturbed members) using the breeding technique to perturb the initial conditions and was run once per day out to 36 h over eastern China for seven months (February-September 2008). Both deterministic and probabilistic forecasts were produced based on individual members, a one-model ensemble, and two-model ensembles. A case study and statistical verification, using both deterministic and probabilistic measuring scores, were performed against fog observations from 13 cities in eastern China. The verification was focused on the 12- and 36-h forecasts. By applying the various approaches, including the new fog detection scheme, ensemble technique, multimodel approach, and the increase in ensemble size, the fog forecast accuracy was steadily and dramatically improved in each of the approaches: from basically no skill at all [equitable threat score (ETS) 5 0.063] to a skill level equivalent to that of warm-season precipitation forecasts of the current NWP models (0.334). Specifically, 1) the multivariable-based fog diagnostic method has a much higher detection capability than the liquid water content (LWC)-only based approach. Reasons why the multivariable approach works better than the LWC-only method were also illustrated. 2) The ensemble-based forecasts are, in general, superior to a single control forecast measured both deterministically and probabilistically. The case study also demonstrates that the ensemble approach could provide more societal value than a single forecast to end users, especially for low-probability significant events like fog. Deterministically, a forecast close to the ensemble median is particularly helpful. 3) The reliability of probabilistic forecasts can be effectively improved by using a multimodel ensemble instead of a single-model ensemble. For a small ensemble such as the one in this study, the increase in ensemble size is also important in improving probabilistic forecasts, although this effect is expected to decrease with the increase in ensemble size. © 2010 American Meteorological Society. Source

Brotzge J.,University of Oklahoma | Erickson S.,National Oceanic and Atmospheric Administration
Weather and Forecasting | Year: 2010

During a 5-yr period of study from 2000 to 2004, slightly more than 26% of all reported tornadoes across the United States occurred without an NWS warning being issued. This study examines some of the reasons behind why no warnings were issued with these tornadoes, and what climatological, storm classification, and sociological factors may have played a role in the lack of warnings. This dataset of tornado records was sorted by F scale, geographically by region and weather forecast office (WFO), hour of the day, month of the year, tornado pathlength, tornado-to-radar distance, county population density, and number of tornadoes by day and order of occurrence. Results show that the tornadoes most likely to strike when the public is least likely to be aware were also those tornadoes with the greatest chance of not being warned. Singular tornado events (one tornado report per day within a WFO county warning area) and the first tornado report of the day were the most difficult scenarios on which to warn, with over half of all solitary tornado events not warned. Geographic areas that experienced a significant proportion of weak, solitary, and/or nocturnal tornadoes had a much higher ratio of missed warnings. In general, the stronger the tornado, as estimated from its F-scale rating and/or track length, the greater chance it was warned. However, the tornado distance from radar had a significant impact on tornado warning statistics. In addition, many weak tornadoes were not warned, and the overall ratio of missed tornado warnings to reported tornadoes actually increased over more densely populated regions, likely due to more complete postevent verification. © 2010 American Meteorological Society. Source

Knapp K.R.,National Oceanic and Atmospheric Administration | Kruk M.C.,STG Inc
Monthly Weather Review | Year: 2010

Numerous agencies around the world perform postseason analysis of tropical cyclone position and intensity, a process described as "best tracking." However, this process is temporally and spatially inhomogeneous because data availability, operational techniques, and knowledge have changed over time and differ among agencies. The net result is that positions and intensities often vary for any given storm for different agencies. In light of these differences, it is imperative to analyze and document the interagency differences in tropical cyclone intensities. To that end, maximum sustained winds from different agencies were compared using data from the International Best Track Archive for Climate Stewardship (IBTrACS) global tropical cyclone dataset. Comparisons were made for a recent 5-yr period to investigate the current differences, where linear systematic differences were evident. Time series of the comparisons also showed temporal changes in the systematic differences, which suggest changes in operational procedures. Initial attempts were made to normalize maximum sustained winds by correcting for known changes in operational procedures. The result was mixed, in that the adjustments removed some but not all of the systematic differences. This suggests that more details on operational procedures are needed and that a complete reanalysis of tropical cyclone intensities should be performed. © 2010 American Meteorological Society. Source

Eberhard W.L.,National Oceanic and Atmospheric Administration
Applied Optics | Year: 2010

Equations for Rayleigh scattering in a mixture of gases are derived and compared to frequent approximations in the literature. The traditional Rayleigh scattering equation as modified by King for scatter from a pure gas is correct, whereas another version sometimes appearing in modern literature is erroneous. Use of a mixture's refractive index, which is equivalent to assuming the isotropic molecular polarizabilities of the component gases are identical, is an approximation. Another common approximation is using only number-density weighting of the King factors. Approximation errors can be large when the major components of a mixture have disparate optical properties. Fortunately, the errors for Earth's air are much smaller and comparable to errors from other sources. © 2010. Source

Deser C.,U.S. National Center for Atmospheric Research | Phillips A.S.,U.S. National Center for Atmospheric Research | Alexander M.A.,National Oceanic and Atmospheric Administration
Geophysical Research Letters | Year: 2010

This study compares the global distribution of 20th century SST and marine air temperature trends from a wide variety of data sets including un-interpolated archives as well as globally-complete reconstructions. Apart from the eastern equatorial Pacific, all datasets show consistency in their statistically significant trends, with warming everywhere except the far northwestern Atlantic; the largest warming trends are found in the middle latitudes of both hemispheres. Two of the SST reconstructions exhibit statistically significant cooling trends over the eastern equatorial Pacific, in disagreement with the un-interpolated SST and marine air temperature datasets which show statistically significant warming in this region. Twentieth century trends in tropical marine cloudiness, precipitation and SLP from independent data sets provide physically consistent evidence for a reduction in the strength of the atmospheric Walker Circulation accompanied by an eastward shift of deep convection from the western to the central equatorial Pacific. Copyright © 2010 by the American Geophysical Union. Source

Wang G.,University of Houston | Soler T.,National Oceanic and Atmospheric Administration
Journal of Surveying Engineering | Year: 2012

This study demonstrates the usefulness of an approach based on the Online Positioning User Service (OPUS) provided by the National Geodetic Survey (NGS) of the National Oceanic and Atmospheric Administration (NOAA) to process Global Positioning System (GPS) data and conduct long-term landslide monitoring in the Puerto Rico and Virgin Islands region. Continuous GPS data collected at a creeping landslide site during 2 years were used to evaluate different scenarios for landslide surveying: continuous or campaign, long duration or short duration, morning or afternoon (during different weather conditions). OPUS uses the Continuously Operating Reference Station (CORS) network managed by the NGS as control points and user-collected data to solve for the position of the occupied station (rover). In July 2011, there were 19 NGS CORS sites in the Puerto Rico and Virgin Islands region. This dense GPS network provided a precise and reliable reference frame for subcentimeter-accuracy landslide monitoring in this region. OPUS static solutions (OPUS-S) for sessions as short as 4 h, and OPUS rapid static solutions (OPUS-RS) for sessions as short as 15 min, can achieve subcentimeter horizontal accuracy if the collection of data during extreme weather conditions is avoided. The uncertainty (peak-to-peak error) reported by a single OPUS-S solution differs from the "true" accuracy by a factor of 1.7 for the horizontal components and 1.3 for the vertical component. The uncertainty reported by a single OPUS-RS solution differs from the accuracy by a factor of 1.4 for horizontal components, while the uncertainty of vertical component statistically agrees with the vertical accuracy. This study also indicates that rainfall events can seriously degrade the performance of high-accuracy GPS. Field GPS landslide surveying should avoid rainfall episodes when accompanied by thunderstorms and the passage of detrimental weather fronts. Once appropriate precautions are taken, the results of this investigation show that OPUS-S and OPUS-RS are ideal alternative tools for subcentimeter-accuracy landslide monitoring. © 2012 American Society of Civil Engineers. Source

Maus S.,University of Colorado at Boulder | Maus S.,National Oceanic and Atmospheric Administration
Geochemistry, Geophysics, Geosystems | Year: 2010

While high-degree models of the Earth's gravity potential have been inferred from measurements for more than a decade, corresponding geomagnetic models are difficult to produce. The primary challenge lies in the estimation of the magnetic potential, which is not completely determined by available field intensity measurements and cannot be computed by direct integration. Described here is the methodology behind the third generation of the National Geophysical Data Center's degree 720 magnetic model. Key issues are (1) the ellipsoidal harmonic representation of the magnetic potential, (2) the reduction of ambiguities by a suitable penalty function, and (3) the use of an iterative method to estimate the model coefficients. The NGDC-720 model provides the lithospheric magnetic field vector at any desired location and altitude close to and above the Earth's surface. Anticipated uses are in geological and tectonic studies of the lithosphere, as a local correction for magnetic navigation and heading systems, and the calibration of ground, marine, airborne, and spaceborne magnetometers. The NGDC-720 model is available at http://geomag.org/models/ ngdc720.html and for long-term archive at http://earthref.org/cgi-bin/er.cgi?s= erda.cgi?n=989. Copyright 2010 by the American Geophysical Union. Source

Belter C.W.,National Oceanic and Atmospheric Administration
Scientometrics | Year: 2013

Bibliometric analysis techniques are increasingly being used to analyze and evaluate scientific research produced by institutions and grant funding agencies. This article uses bibliometric methods to analyze journal articles funded by NOAA's Office of Ocean Exploration and Research (OER), an extramural grant-funding agency focused on the scientific exploration of the world's oceans. OER-supported articles in this analysis were identified through grant reports, personal communication, and acknowledgement of OER support or grant numbers. The articles identified were analyzed to determine the number of publications and citations received per year, subject, and institution. The productivity and citation impact of institutions in the US receiving OER grant funding were mapped geographically. Word co-occurrence and bibliographic coupling networks were created and visualized to identify the research topics of OER-supported articles. Finally, article citation counts were evaluated by means of percentile ranks. This article demonstrates that bibliometric analysis can be useful for summarizing and evaluating the research performance of a grant funding agency. © 2012 The Author(s). Source

Lack D.A.,National Oceanic and Atmospheric Administration | Lack D.A.,University of Colorado at Boulder | Cappa C.D.,University of California at Davis
Atmospheric Chemistry and Physics | Year: 2010

The presence of clear coatings on atmospheric black carbon (BC) particles is known to enhance the magnitude of light absorption by the BC cores. Based on calculations using core/shell Mie theory, we demonstrate that the enhancement of light absorption (EAbs) by atmospheric black carbon (BC) when it is coated in mildly absorbing material (CBrown) is reduced relative to the enhancement induced by non-absorbing coatings (CClear). This reduction, sensitive to both the CBrown coating thickness and imaginary refractive index (RI), can be up to 50% for 400 nm radiation and 25% averaged across the visible radiation spectrum for reasonable core/shell diameters. The enhanced direct radiative forcing possible due to the enhancement effect of CClear is therefore reduced if the coating is absorbing. Additionally, the need to explicitly treat BC as an internal, as opposed to external, mixture with CBrown is shown to be important to the calculated single scatter albedo only when models treat BC as large spherical cores (>50 nm). For smaller BC cores (or fractal agglomerates) consideration of the BC and CBrown as an external mixture leads to relatively small errors in the particle single scatter albedo of <0.03. It has often been assumed that observation of an absorption Angström exponent (AAE)>1 indicates absorption by a non-BC aerosol. Here, it is shown that BC cores coated in CClear can reasonably have an AAE of up to 1.6, a result that complicates the attribution of observed light absorption to CBrown within ambient particles. However, an AAE<1.6 does not exclude the possibility of CBrown; rather CBrown cannot be confidently assigned unless AAE>1.6. Comparison of these model results to various ambient AAE measurements demonstrates that large-scale attribution of CBrown is a challenging task using current in-situ measurement methods. We suggest that coincident measurements of particle core and shell sizes along with the AAE may be necessary to distinguish absorbing and non-absorbing OC. © Author(s) 2010. Source

Lin M.,University of Wisconsin - Madison | Holloway T.,University of Wisconsin - Madison | Carmichael G.R.,University of Iowa | Fiore A.M.,National Oceanic and Atmospheric Administration
Atmospheric Chemistry and Physics | Year: 2010

Understanding the exchange processes between the atmospheric boundary layer and the free troposphere is crucial for estimating hemispheric transport of air pollution. Most studies of hemispheric air pollution transport have taken a large-scale perspective using global chemical transport models with fairly coarse spatial and temporal resolutions. In support of United Nations Task Force on Hemispheric Transport of Air Pollution (TF HTAP; www.htap.org), this study employs two high-resolution atmospheric chemistry models (WRF-Chem and CMAQ; 36×36 km) driven with chemical boundary conditions from a global model (MOZART; 1.9×1. 9°) to examine the role of fine-scale transport and chemistry processes in controlling pollution export and import over the Asian continent in spring (March 2001). Our analysis indicates the importance of rapid venting through deep convection that develops along the leading edge of frontal system convergence bands, which are not adequately resolved in either of two global models compared with TRACE-P aircraft observations during a frontal event. Both regional model simulations and observations show that frontal outflows of CO, O3 and PAN can extend to the upper troposphere (6ĝ€"9 km). Pollution plumes in the global MOZART model are typically diluted and insufficiently lofted to higher altitudes where they can undergo more efficient transport in stronger winds. We use sensitivity simulations that perturb chemical boundary conditions in the CMAQ regional model to estimate that the O3 production over East Asia (EA) driven by PAN decomposition contributes 20% of the spatial averaged total O3 response to European (EU) emission perturbations in March, and occasionally contributes approximately 50% of the total O3 response in subsiding plumes at mountain observatories (at approximately 2 km altitude). The response to decomposing PAN of EU origin is strongly affected by the O3 formation chemical regimes, which vary with the model chemical mechanism and NOx/VOC emissions. Our high-resolution models demonstrate a large spatial variability (by up to a factor of 6) in the response of local O3 to 20% reductions in EU anthropogenic O3 precursor emissions. The response in the highly populated Asian megacities is 40ĝ€"50% lower in our high-resolution models than the global model, suggesting that the source-receptor relationships inferred from the global coarse-resolution models likely overestimate health impacts associated with intercontinental O3 transport. Our results highlight the important roles of rapid convective transport, orographic forcing, urban photochemistry and heterogeneous boundary layer processes in controlling intercontinental transport; these processes may not be well resolved in the large-scale models. © Author(s) 2010. Source

Xu J.,The Center for Satellite Applications and Research | Powell Jr. A.M.,National Oceanic and Atmospheric Administration
Geophysical Research Letters | Year: 2010

Based on the ensemble spread, a methodology of measuring uncertainty in weather forecasts, the temperature trend and spread have been estimated using five radiosonde data sets and seven reanalysis products beginning in 1989. The results show that the magnitude of warming or cooling depends on the data sources, atmospheric heights, and geophysical latitudes. Over low-middle latitudes, the cooling varies from -2.6 K/decade in NCEP-DOE to -0.8 K/decade in HADAT2 in the lower stratosphere. The warming weakly changes from 0.2 through 0.4 K/decade in the middle troposphere. Over Antarctica, there is a pronounced warming in the low-middle troposphere in the three NCEP reanalyses and the RATPAC radiosonde data sets, and cooling in the other eight products. Over the Arctic, the warming is observed from the lower troposphere to the lower stratosphere in all twelve data sets. Significant cooling is identified over the middle stratosphere (above 50 hPa) in all five radiosondes. For global mean temperature, the trend is approximately 0.2 K/decade in the troposphere and -0.8 K/decade in the stratosphere. The spread increases significantly with atmospheric height from approximately 0.1 K/decade at 850hPa to 0.8 K/decade at 30hPa. The spread in the reanalysis data sets is much larger than in the radiosondes in the stratosphere. In contrast, the spread in both the reanalysis and radiosondes data sets is very small and shows the trend in better agreement with each other in the troposphere. © 2010 by the American Geophysical Union. Source

Jefferson A.,University of Colorado at Boulder | Jefferson A.,National Oceanic and Atmospheric Administration
Atmospheric Chemistry and Physics | Year: 2010

This study presents an empirical method to estimate the CCN concentration as a function of percent supersaturation. The aerosol optical properties, backscatter fraction and single scatter albedo, function as proxies for the aerosol size and composition in a power law relationship to CCN. This method is tested at four sites with aged aerosol: SGP (Oklahoma, USA), FKB (Black Forest, Germany), HFE (Hefei, China) and GRW (Graciosa, Azores). Each site represents a different aerosol type and thus demonstrates the method robustness and limitations. Good agreement was found between the calculated and measured CCN with slopes between 0.81 and 1.03 and correlation coefficients (r2 values) between 0.59 and 0.67. The fit quality declined at low CCN concentrations. © Author(s) 2010. Source

Kane J.,National Oceanic and Atmospheric Administration
Journal of Northwest Atlantic Fishery Science | Year: 2010

Interannual zooplankton abundance trends in the Middle Atlantic Bight region of the US Northeast continental shelf are described and related to variations in environmental variables for the years 1977 to 2009. Depth integrated plankton samples were collected on bimonthly broad-scale surveys of the region. Abundance information indicates that the region's zooplankton population is flourishing. Total counts and biomass levels have been mostly above average in the second-half of the sampling period. Multivariate analysis of abundance data supported these findings by classifying the time series into three consecutive groups of years defined by varying abundance levels: 1) average in the late 1970s, 2) low in the 1980s, and 3) above average from 1993 to 2009. This analysis identified eleven taxa that had similar increasing interannual abundance patterns during the time series. Evidence is presented that these changes may be related to warming temperatures in the Northwest Atlantic. The increasing abundance levels of the eleven taxa was positively correlated (p<0.01) to surface temperature measurements and the recent trends of the Atlantic Multidecadal Oscillation index. A second, smaller group of six taxa had correlated abundance trends that were variable through the years, with peak production associated with low salinity in the late 1990s. Source

Rocha A.V.,National Oceanic and Atmospheric Administration | Goulden M.L.,University of California at Irvine
Journal of Geophysical Research: Biogeosciences | Year: 2010

Experimental manipulations provide a powerful tool for understanding an ecosystem's response to environmental perturbation. We combined paired eddy covariance towers with an experimental manipulation of water availability to determine the response of marsh carbon balance to drought. We monitored the Net Ecosystem Exchange of CO2 (NEE) in two ponds from 2004 to 2009 at the San Joaquin Freshwater Marsh (SJFM), and subjected one of the ponds to a yearlong drought treatment in 2007. The two ponds experienced similar flooding and environmental regimes before and after the drought, ensuring that differences between ponds were largely attributable to the 2007 drought. Drought substantially reduced surface greenness, as measured by the Enhanced Vegetation Index (EVI) and photosynthetic carbon sequestration, primarily by inhibiting leaf area development. Respiratory carbon losses were less influenced by drought than photosynthetic carbon gains. The effect of the drought lasted several years, with delayed leaf area development and peak carbon uptake rates during the subsequent year, and reduced leaf area for a couple of years. The combined effect of the drought and legacy effects created an overall loss of carbon that was equivalent to 4 years of the maximum annual carbon sequestration observed over a decade. Our results indicate that drought can have long-term impacts on ecosystem carbon balance and that future projected drought increases in Southern California will have a negative impact on marsh carbon sequestration. Copyright 2010 by the American Geophysical Union. Source

Smayda T.J.,University of Rhode Island | Trainer V.L.,National Oceanic and Atmospheric Administration
Progress in Oceanography | Year: 2010

The influence of diatom bloom behaviour, dinoflagellate life cycles, propagule type and upwelling bloom cycles on the seeding of dinoflagellate blooms in eastern boundary current upwelling systems is evaluated. Winter-spring diatom bloom behaviour is contrasted with upwelling bloom behaviour because their phenology impacts dinoflagellate blooms. The winter-spring diatom bloom is usually sustained, whereas the classical upwelling diatom bloom occurs as a series of separate, recurrent mini-blooms intercalated by upwelling-relaxation periods, during which dinoflagellates often bloom. Four sequential wind-regulated phases characterize upwelling cycles, with each phase having different effects on diatom and dinoflagellate bloom behaviour: bloom "spin up", bloom maximum, bloom "spin down", and upwelling relaxation. The spin up - bloom maximum is the period of heightened diatom growth; the spin down - upwelling-relaxation phases are the periods when dinoflagellates often bloom. The duration, intensity and ratio of the upwelling and relaxation periods making up upwelling cycles determine the potential for dinoflagellate blooms to develop within a given upwelling cycle and prior to the subsequent "spin up" of upwelling that favours diatom blooms. Upwelling diatoms and meroplanktonic dinoflagellates have three types of propagules available to seed blooms: vegetative cells, resting cells and resting cysts. However, most upwelling dinoflagellates are holoplanktonic, which indicates that the capacity to form resting cysts is not an absolute requirement for growth and survival in upwelling systems. The long-term (decadal) gaps in bloom behaviour of Gymnodinium catenatum and Lingulodinium polyedrum, and the unpredictable bloom behaviour of dinoflagellates generally, are examined from the perspective of seeding strategies. Mismatches between observed and expected in situ bloom behaviour and resting cyst dynamics are common among upwelling dinoflagellates. This disassociation suggests unrecognized upwelling system factors that fall within the physical-chemical-biological domain are more important than life cycle in selecting dinoflagellates species having the survival-seeding strategies and ecophysiological adaptations required for growth in physically robust upwelling systems. It is conjectured that diatom life cycles, as a group, are geared towards exploiting seeding opportunities, whereas dinoflagellates have evolved life-cycle behaviour more attuned to survival. The role of ecological dormancy and ecological release from bloom inhibition underlying dinoflagellate bloom irregularity is considered. The expectation that the dinoflagellate species selected to bloom from among the common upwelling flora would be the same in all eastern boundary upwelling systems is not realized. © 2010 Elsevier Ltd. All rights reserved. Source

Charette M.A.,Woods Hole Oceanographic Institution | Smith W.H.F.,National Oceanic and Atmospheric Administration
Oceanography | Year: 2010

Despite playing a significant role in the global water cycle, ocean volume has not been re-examined in over 25 years. The main uncertainty associated with ocean volume is the mean ocean depth. The earliest studies tended to overestimate ocean depth due to undersampling of seamounts and ocean ridges. The advent of the echosounder in the 1920s and subsequent ship-borne technologies rapidly increased aerial coverage of the ocean; hence, over time there has been a gradual decrease in calculated mean ocean depth. Today, however, in situ measurements span only ~ 10% of the ocean's surface area. Here, we use satellite altimetry data to estimate the ocean's volume, which is lower by a volume equivalent to 500 times the Great Lakes or five times the Gulf of Mexico when compared to the most recent published estimates. © 2010 by The Oceanography Society. Source

Zou C.-Z.,The Center for Satellite Applications and Research | Wang W.,National Oceanic and Atmospheric Administration
Journal of Atmospheric and Oceanic Technology | Year: 2010

Warm target effect and diurnal drift errors are the main sources of uncertainties in the trend determination from the NOAA Microwave Sounding Unit (MSU) observations. Currently, there are two methods to correct the warm target effect: 1) finding a best root-level (level-1c) calibration nonlinearity using simultaneous nadir overpass (SNO) matchups to minimize this effect for each scene radiance, and 2) finding a best-fit empirical relationship between the correction term of the end-level gridded brightness temperature and warm target temperature and then removing the best fit from the unadjusted time series. The former corrects the warm target effect before the diurnal drift adjustment and provides more accurate, warm target effect-minimized, level-1c scene radiances for reanalysis applications. The latter corrects the warm target effect at the end-level merging step, which depend on the diurnal drift correction that occurred at a previous step. Although minimized, the first method still leaves small residual warm target-related errors due to imperfect calibrations. This study demonstrates that when the diurnal drift effect is negligible, a combination of the two methods completely removes warm target effect and produces an invariant trend that is independent of the level-1c calibration in the SNO framework. The conclusion is directly applicable to the MSU channel-2 oceanic mid-tropospheric temperature (T2) and global channel-3 upper-tropospheric temperature (T3) and channel-4 lower-stratospheric temperature (T4), which satisfy the condition of negligible diurnal drift effect. On the basis of these results, version 1.2 of the National Environmental Satellite, Data, and Information Service (NESDIS)-Center for Satellite Applications and Research (STAR) multisatellite MSU time series was constructed, including all T2, T3, and T4 products. In addition, a diurnal drift correction based on the Remote Sensing Systems diurnal anomalies was applied to the T2 product, which produces consistent climate trends between land and ocean. The global long-term climate trends for T2 and T4 derived from the STAR V1.2 dataset are, respectively, 0.18 ± 0.05 and -0.39 ± 0.36 K decade-1 during 1979-2006; the T3 trend is 0.11 ± 0.08 K decade-1 for 1981-2006. © 2010 American Meteorological Society. Source

Tomberlin D.,National Oceanic and Atmospheric Administration
Marine Resource Economics | Year: 2010

The marbled murrelet (Brachyramphus marmoratus,) is an endangered seabird that nests in coastal forests from Alaska to California. The value of these forests for human use, coupled with the difficulty of determining whether a forest stand is occupied by nesting marbled murrelets, poses a dilemma for land managers. Should they implement a costly survey to gather information on whether a potential nest site is occupied, or should they allow human use, effectively assuming the site is unoccupied? This article demonstrates the application of the partially observable Markov decision process (POMDP) as a framework for addressing this question. The analysis yields a policy in which the optimal action is a function of the decision-maker's subjective probability that a potential nest site is occupied by marbled murrelets. By incorporating stochastic state dynamics and the choice of whether to invest in learning, the POMDP provides a formal representation of adaptive management when active learning is possible. Copyright © 2010 MRE Foundation, Inc. Source

Wang M.,University of Washington | Overland J.E.,National Oceanic and Atmospheric Administration | Bond N.A.,University of Washington
Journal of Marine Systems | Year: 2010

In preparation for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) modeling centers from around the world carried out sets of global climate simulations under various emission scenarios with a total of 23 coupled atmosphere-ocean general circulation models. We evaluated the models' 20th century hindcasts of selected variables relevant to several large marine ecosystems and examined 21st century projections by a subset of these models under the A1B (middle range) emission scenario. In general we find that a subset (about half) of the models are able to simulate large-scale aspects of the historical observations reasonably well, which provides some confidence in their application for projections of ocean conditions into the future. Over the North Pacific by the mid-21st century, the warming due to the trend in wintertime sea surface temperature (SST) will be 1°-1.5 °C, which is as large as the amplitude of the major mode of variability, the Pacific Decadal Oscillation (PDO). For areas northwest of the Hawaiian Islands, these models projected a steady increase of 1.2 °C in summer SST over the period from 2000 to 2050. For the Bering and Barents seas, a subset of models selected on the basis of their ability to simulate sea-ice area in late 20th century yield an average decrease in sea-ice coverage of 43% and 36%, respectively, by the decade centered on 2050 with a reasonable degree of consistency. On the other hand, model simulations of coastal upwelling for the California, Canary and Humboldt Currents, and of bottom temperatures in the Barents Sea, feature a relatively large degree of uncertainty. These results illustrate that 21st century projections for marine ecosystems in certain regions using present-generation climate models require additional analysis. © 2009 Elsevier B.V. Source

Wetherald R.T.,National Oceanic and Atmospheric Administration
Climatic Change | Year: 2010

This paper examines the subject of hydrologic variability and its changes in two separate integrations of a coupled ocean-atmosphere general circulation model developed at the Geophysical Fluid Dynamics Laboratory/NOAA assuming a 1% per year increase to a doubling and quadrupling of CO2, respectively. Changes in time mean state and variability of precipitation, runoff and soil moisture are evaluated using monthly and seasonal mean data derived from these integrations. Various statistical tests are then performed on the resulting time mean and variability changes. The patterns of hydrologic change for these three quantities are similar to those obtained from previous studies. In northern middle to higher latitudes for the time means, the changes include increases in monthly mean precipitation, increases in monthly mean runoff during the fall, winter and spring seasons and decreases of monthly mean soil moisture during summer. Many of these changes are found to be statistically significant at the 5% significance level for both the time mean and variability especially for the results where CO2 is quadrupled such as monthly mean precipitation. Significant changes also include increases of runoff variability during spring, winter and spring and increases of soil moisture variability during the summer season. These results support statements made in previous IPCC reports that increasing greenhouse gases can lead to more severe and frequent floods and droughts depending upon season and latitude. This study also indicates that the approaches to equilibrium of these two integrations, and the resulting hydrologic changes, take place over time scales of hundreds of years in agreement with several previous investigations. © 2009 The Author(s). Source

Egleston E.S.,Princeton University | Sabine C.L.,National Oceanic and Atmospheric Administration | Morel F.M.M.,Princeton University
Global Biogeochemical Cycles | Year: 2010

We derive explicit expressions of the Revelle factor and several other buffer factors of interest to climate change scientists and those studying ocean acidification. These buffer factors quantify the sensitivity of CO2 and H+ concentrations ([CO2] and [H+]) and CaCO3 saturation () to changes in dissolved inorganic carbon concentration (DIC) and alkalinity (Alk). The explicit expressions of these buffer factors provide a convenient means to compare the degree of buffering of [CO2], [H+], and in different regions of the oceans and at different times in the future and to gain insight into the buffering mechanisms. All six buffer factors have roughly similar values, and all reach an absolute minimum when DIC = Alk (pH ∼ 7.5). Surface maps of the buffer factors generally show stronger buffering capacity in the subtropical gyres relative to the polar regions. As the dissolution of anthropogenic CO 2 increases the DIC of surface seawater over the next century, all the buffer factors will decrease, resulting in a much greater sensitivity to local variations in DIC and Alk. For example, diurnal and seasonal variations in pH and caused by photosynthesis and respiration will be greatly amplified. Buffer factors provide convenient means to quantify the effect that changes in DIC and Alk have on seawater chemistry. They should also help illuminate the role that various physical and biological processes have in determining the oceanic response to an increase in atmospheric CO2. Copyright 2010 by the American Geophysical Union. Source

Byrne R.H.,University of South Florida | Mecking S.,University of Washington | Feely R.A.,National Oceanic and Atmospheric Administration | Liu X.,University of South Florida
Geophysical Research Letters | Year: 2010

Global ocean acidification is a prominent, inexorable change associated with rising levels of atmospheric CO2. Here we present the first basin-wide direct observations of recently declining pH, along with estimates of anthropogenic and non-anthropogenic contributions to that signal. Along 152°W in the North Pacific Ocean (22-56 °N), pH changes between 1991 and 2006 were essentially zero below about 800 m depth. However, in the upper 500 m, significant pH changes, as large as -0.06, were observed. Anthropogenic and non-anthropogenic contributions over the upper 800 m are estimated to be of similar magnitude. In the surface mixed layer (depths to ∼100 m), the extent of pH change is consistent with that expected under conditions of seawater/atmosphere equilibration, with an average rate of change of -0.0017/yr. Future mixed layer changes can be expected to closely mirror changes in atmospheric CO2, with surface seawater pH continuing to fall as atmospheric CO2 rises. © Copyright 2010 by the American Geophysical Union. Source

Scharroo R.,Altimetrics LLC | Smith W.H.F.,National Oceanic and Atmospheric Administration
Journal of Geophysical Research: Space Physics | Year: 2010

The total electron content (TEC) in the ionosphere is an important factor in the propagation of radio waves. Since 1998 the coverage global positioning system (GPS) observations has been sufficient to monitor the TEC globally. We have used the global ionosphere maps provided by the Jet Propulsion Laboratory to devise a new ionosphere climatology (NIC09). The climatology fits the GPS maps to 4.5 TECU, more than twice as well as the IRI2007 climatology. The use of the global mean TEC as the input parameter reduces scaling errors and long-term mean errors in the model. For climatic studies of sea level measured by satellite radar altimeters, it is necessary to go back before 1998. During the earlier years of radar altimetry, we use TOPEX dual-frequency altimeter data to reconstruct the global mean TEC or use the solar radio flux (F10.7) as a proxy. The comparison of dual-frequency altimeter data with the GPS maps demonstrated that about 8% of the TEC extends above 1350 km and about 14% above 800 km. The root mean square error of the NIC09 climatology was found to be approximately 18% of the TEC, compared to 14% for the GPS TEC maps, and 35% for IRI2007. Copyright 2010 by the American Geophysical Union. Source

Methot Jr. R.D.,National Oceanic and Atmospheric Administration | Taylor I.G.,University of Washington
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2011

Integrated analysis models provide a tool to estimate fish abundance, recruitment, and fishing mortality from a wide variety of data. The flexibility of integrated analysis models allows them to be applied over extended time periods spanning historical decades with little information from which to estimate the annual signal of recruitment variability to modern periods in which more information about recruitment variability exists. Across this range of data availability, the estimation process must assure that the estimated log-normally distributed recruitments are mean unbiased to assure mean unbiased biomass estimates. Here we show how the estimation method implemented in the integrated analysis model, Stock Synthesis, achieves this unbiased characteristic in a penalized likelihood approach that is comparable to the results from Markov chain Monte Carlo. The total variability in recruitment is decomposed into variability among annual recruitment estimates based on information in the data and a residual variability. Because data are never perfectly informative, we show that estimated recruitment variability will always be less than the true variability among recruitments and that the method implemented here can be used to iteratively estimate the true variability among recruitments. Source

Gobler C.J.,State University of New York at Stony Brook | Sunda W.G.,National Oceanic and Atmospheric Administration
Harmful Algae | Year: 2012

Brown tides of the pelagophytes Aureococcus anophagefferens Hargraves et Sieburth and Aureoumbra lagunensis DeYoe et Stockwell have formed ecosystem disruptive algal blooms in shallow estuaries of the United States and South Africa for more than two decades. These algae achieve maximum growth rates at low light and nutrient levels and are able to utilize a wide variety of organic nutrient (N and P) substrates. They also experience low mortality losses via their ability to discourage grazing by zooplankton and filter feeding mollusks. Observations and conceptual and numerical models have indicated the importance of 'pre-blooms' of competing high nutrient-adapted phytoplankton that reduce available nutrients to low levels prior to the formation of many brown tide blooms, especially those of Aureococcus. These models suggest that brown tides are promoted by positive feedback mechanisms involving the ability of these algae to grow competitively at low nutrient and light levels, their low rates of grazing mortality, and the associated low grazing-mediated recycling of nutrients. The latter further reduces nutrient concentrations, which further favors competitive population growth of the brown tide species, thereby promoting blooms. Molecular and genomic studies of brown tides have identified the genes that encode many of the key proteins that facilitate bloom formation and persistence. Brown tides are among the most widely studied harmful algal blooms (HABs), which makes them ideal model systems for identifying the factors and complex mechanisms that promote HAB events. As such, several promising bloom mitigation strategies are now apparent. © 2011 Elsevier B.V. Source

Churnside J.H.,National Oceanic and Atmospheric Administration
Optics Express | Year: 2010

The lidar signature from a collection of bubbles is proportional to the volume backscatter coefficient at a scattering angle of 180°. This quantity, calculated using a combination of geometric optics and diffraction, is proportional to the void fraction of the bubbles in the water for any bubble size distribution. The constant of proportionality is 233 m-1 sr -1for clean bubbles, slightly less for bubbles coated with a thin layer of organic material, and as large as 1445 m-1 sr-1 for a thick coating of protein. © 2010 Optical Society of America. Source

Solomon A.,National Oceanic and Atmospheric Administration | Solomon A.,University of Colorado at Boulder
Geophysical Research Letters | Year: 2010

Niño/Southern Oscillation (ENSO) events are known to force atmospheric teleconnections that impact extratropical sea surface temperatures and surface winds. In this paper we use focused model experiments to investigate whether this extratropical variability can feedback to, and significantly impact, the Tropics through ocean Rossby waves. We use an atmospheric general circulation model coupled to a reduced gravity Pacific Ocean model to isolate these potential feedback loops and quantify their impact on ENSO variability. We find that anomalous winds and heat fluxes located in regions of maximum mean subduction in the subtropical North Pacific trigger ocean Rossby waves that take approximately four years to reach the equator. Most notably, we demonstrate that this feedback loop causes a primarily 2-year ENSO, when only the Tropics is coupled, to shift to a more realistic broad 2-5 year range by damping ∼2 year variability and amplifying ∼4 year variability. © Copyright 2010 by the American Geophysical Union. Source

Shen Y.,National Meteorological Information Center | Xiong A.,National Meteorological Information Center | Wang Y.,National Meteorological Information Center | Xie P.,National Oceanic and Atmospheric Administration
Journal of Geophysical Research: Atmospheres | Year: 2010

A gauge-based analysis of hourly precipitation is constructed on a 0.25° latitude/ longitude grid over China for a 3 year period from 2005 to 2007 by interpolating gauge reports from∼2000 stations collected and quality controlled by the National Meteorological Information Center of the China Meteorological Administration. Gauge-based precipitation analysis is applied to examine the performance of six high-resolution satellite precipitation estimates, including Joyce et al.'s (2004) Climate Prediction Center Morphing Technique (CMORPH) and the arithmetic mean of the microwave estimates used in CMORPH; Huffman et al.'s (2007) Tropical Rainfall Measuring Mission (TRMM) precipitation product 3B42 and its real-time version 3B42RT; Turk et al.'s (2004) Naval Research Laboratory blended product; and Hsu et al.'s (1997) Precipitation Estimation From Remotely Sensed Information Using Artificial Neural Network (PERSIANN). Our results showed the following: (1) all six satellite products are capable of capturing the overall spatial distribution and temporal variations of precipitation reasonably well; (2) performance of the satellite products varies for different regions and different precipitation regimes, with better comparison statistics observed over wet regions and for warm seasons; (3) products based solely on satellite observations present regionally and seasonally varying biases, while the gauge-adjustment procedures applied in TRMM 3B42 remove the large-scale bias almost completely; (4) CMORPH exhibits the best performance in depicting the spatial pattern and temporal variations of precipitation; and (5) both the relative magnitude and the phase of the warm season precipitation over China are estimated quite well, but the early morning peak associated with the Mei-Yu rainfall over central eastern China is substantially under-estimated by all satellite products. Copyright © 2010 by the American Geophysical Union. Source

Alexander M.,National Oceanic and Atmospheric Administration
Geophysical Monograph Series | Year: 2010

We examine processes that influence North Pacific sea surface temperature (SST) anomalies including surface heat fluxes, upper ocean mixing, thermocline variability, ocean currents, and tropical-extratropical interactions via the atmosphere and ocean. The ocean integrates rapidly varying atmospheric heat flux and wind forcing, and thus a stochastic model of the climate system, where white noise forcing produces a red spectrum, appears to provide a baseline for SST variability even on decadal time scales. However, additional processes influence Pacific climate variability including the "reemergence mechanism," where seasonal variability in mixed layer depth allows surface temperature anomalies to be stored at depth during summer and return to the surface in the following winter. Wind stress curl anomalies in the central/east Pacific drive thermocline variability that propagates to the west Pacific via baroclinic Rossby waves and influences SST by vertical mixing and the change in strength and position of the ocean gyres. Atmospheric changes associated with the El Niño-Southern Oscillation (ENSO) also influence North Pacific SST anomalies via the "atmospheric bridge." The dominant pattern of North Pacific SST anomalies, the Pacific Decadal Oscillation (PDO), exhibits variability on interannual as well as decadal time scales. Unlike ENSO, the PDO does not appear to be a mode of the climate system, but rather it results from several different mechanisms including (1) stochastic heat flux forcing associated with random fluctuations in the Aleutian Low, (2) the atmospheric bridge augmented by the reemergence mechanism, and (3) wind-driven changes in the North Pacific gyres. Copyright © 2010 by the American Geophysical Union. Source

Leuliette E.W.,National Oceanic and Atmospheric Administration | Scharroo R.,Altimetrics LLC
Marine Geodesy | Year: 2010

The observation strategy for satellite radar altimetry includes both inter-satellite calibration and calibration with a network of tide gauges. These cross-comparisons are valuable tools for identifying sources of error and for establishing progress toward a sea level climate data record.Demonstrating the capabilities of the Radar Altimetry Database System (RADS) as a platform for climate data records, we show comparisons of Jason-2 with Jason-1 and Envisat that illustrate errors associated with solar intensity and tracker bias. A multi-mission tide gauge calibration shows a drift in the 17-year sea level record of –0.04 ± 0.4 mm/yr. © 2010, Taylor & Francis Group, LLC. Source

Walters A.W.,Yale University | Walters A.W.,National Oceanic and Atmospheric Administration
Journal of the North American Benthological Society | Year: 2011

Low-flow disturbances are predicted to increase in frequency and intensity because of climate change and extensive human water withdrawal, but the effect of decreased flow on aquatic insect communities is not well understood. I explored the resistance of aquatic insects to reduced flow by creating an experimental low-flow disturbance that diverted ∼40 to 80% of the water in 3 replicate streams for 2 summers. I sampled the aquatic insect community in control and treatment reaches before and during the 3-mo water diversions. I used a trait-based approach to analyze the data because traits have the potential to increase mechanistic understanding and predictive capabilities. The analysis focused on 6 traits: desiccation resistance, maximum crawling rate, armoring, size at maturity, rheophily, and habit. Community trait composition underwent strong seasonal shifts, but few consistent responses to reduced flow were observed. The 2 trait states that did appear to confer increased resistance were high crawling rate and armoring. These trait states can provide protection from predators. Thus, biotic interactions might be important during low-flow disturbance. © 2011 The North American Benthological Society. Source

Grell G.,National Oceanic and Atmospheric Administration | Baklanov A.,Danish Meteorological Institute
Atmospheric Environment | Year: 2011

This paper discusses some of the differences between online and offline approaches for both air quality forecasting and numerical weather prediction, and argues in favor of an eventual migration to integrated modeling systems that allow two-way interactions of physical and chemical processes. Recent studies are used that directly compared online and offline simulations to discuss possible shortcomings for both air quality and weather forecasting. The disadvantages of offline approaches are easy to show for air quality forecasting. On the other hand, a positive impact on short to medium range weather forecasts that is significant enough to justify an implementation at operational weather forecasting centers is more difficult to prove, and may initially only come through an improvement of the meteorological data assimilation. Eventually though, a migration to an integrated modeling system will provide new opportunities for weather prediction modelers as well. The simulation of chemical species will allow identification of shortcomings in currently used forecast models as well as lead to better use of meteorological data assimilation. © 2011 Elsevier Ltd. Source

Howard T.A.,Southwest Research Institute | Deforest C.E.,Southwest Research Institute | Reinard A.A.,National Oceanic and Atmospheric Administration
Astrophysical Journal | Year: 2012

This paper presents results utilizing a new data processing pipeline for STEREO/SECCHI. The pipeline is used to identify and track 24 large- and small-scale solar wind transients from the Sun out to 1 AU. This comparison was performed during a few weeks around the minimum at the end of Solar Cycle 23 and the start of Cycle 24 (2008 December to 2009 January). We use coronagraph data to identify features near the Sun, track them through HI-2A, and identify their signatures with in situ data at the Earth and STEREO-B. We provide measurements and preliminary analysis of the in situ signatures of these features near 1 AU. Along with the demonstration of the utility of heliospheric imagers for tracking even small-scale structures, we identify and discuss an important limitation in using geometric triangulation for determining three-dimensional properties. © 2012. The American Astronomical Society. All rights reserved.. Source

Gurarie E.,University of Helsinki | Gurarie E.,National Oceanic and Atmospheric Administration | Ovaskainen O.,University of Helsinki
American Naturalist | Year: 2011

Animal movements have been modeled with diffusion at large scales and with more detailed movement models at smaller scales. We argue that the biologically relevant behavior of a wide class of movement models can be efficiently summarized with two parameters: the characteristic temporal and spatial scales of movement. We define these scales so that they describe movement behavior both at short scales (through the velocity autocorrelation function) and at long scales (through the diffusion coefficient). We derive these scales for two types of commonly used movement models: the discrete-step correlated random walk, with either constant or random step intervals, and the continuous-time correlated velocity model. For a given set of characteristic scales, the models produce very similar trajectories and encounter rates between moving searchers and stationary targets. Thus, we argue that characteristic scales provide a unifying currency that can be used to parameterize a wide range of ecological phenomena related to movement. © 2011 by The University of Chicago. Source

Matrosov S.Y.,University of Colorado at Boulder | Cifelli R.,National Oceanic and Atmospheric Administration | Gochis D.,U.S. National Center for Atmospheric Research
Journal of Applied Meteorology and Climatology | Year: 2013

The utility of X-band polarimetric radar to provide rainfall estimations with high spatial and temporal resolution in heavy convective precipitation in the presence of hail is explored. A case study involving observations of strong convective cells with a transportable polarimetric X-band radar near Boulder, Colorado, is presented. These cells produced rain-hail mixtures with a significant liquid fraction, causing local flash floods and debris flow in an environmentally sensitive burn area that had been previously affected by wildfire. It is demonstrated that the specific differential phase shift (KDP)-based rainfall estimator provided liquid accumulations that were in relatively good agreement with a network of high-density rain gauges and experimental disdrometers. This estimator was also able to capture the significant variability of accumulated rainfall in a relatively small area of interest, and the corresponding results were not significantly affected by hail. Hail presence, however, was a likely reason for significant overestimation of rainfall retrievals for X-band radar approaches that are based on radar-reflectivity Ze measurements that have been corrected for attenuation in rain. Even greater overestimations were observed with the S-band radar of the weather-service network. In part because of larger range distances, these radar data could not correctly reproduce the spatial variability of rainfall in the burn area. ©2013 American Meteorological Society. Source

Miller K.B.,National Oceanic and Atmospheric Administration
Marine Biology | Year: 2016

Controlling the spread of marine invasive species is a challenging and costly task. Maps that predict the potential spread of an invader based on known habitat preferences can be extremely valuable for assessing invasion risk and prioritizing management actions for invasion control or prevention. Most maps are developed by using environmental data on the species’ known distribution to map the potential niche of the species in a new location. However, this approach is complicated when a species spreads to an area where environmental conditions are much different than in other places it is known to exist. Didemnum vexillum was discovered in Southeast Alaska in 2010, marking the northernmost known range of this species. A self-organizing map (SOM) was used to assess potential habitat for D. vexillum in other parts of Southeast Alaska using summer and winter temperature and salinity as controlling factors. This research highlights the uncertainty of using the species’ current distribution to evaluate potential spread to an environment at the edge of a species’ environmental tolerances. It also identifies gaps in our knowledge of D. vexillum thermal and salinity tolerances, including potential synergistic and additive effects of both low temperature and low salinity, which limit investigation of mechanistic modeling methods. © 2016, Springer-Verlag Berlin Heidelberg (Outside the USA). Source

Chiodi A.M.,University of Washington | Harrison D.E.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2013

This study shows that, since 1979 when outgoing longwave radiation (OLR) observations became reliably available, most of the useful U.S. seasonal weather impact of El Niño events is associated with the few events identified by the behavior of outgoing longwave radiation (OLR) over the eastern equatorial Pacific ("OLR- El Nin~o events"). These events produce composite seasonal regional weather anomalies that are 95% statistically significant and robust (associated with almost all events). Results also show that there are very few statistically significant seasonal weather anomalies, even at the 80% level, associated with the non-OLR-El Niño events. A major enhancement of statistical seasonal forecasting skill over the contiguous United States appears possible by incorporating these results. It is essential to respect that not all events commonly labeled as El Niño events lead to statistically useful U.S. seasonal forecast skill. © 2013 American Meteorological Society. Source

Avnery S.,Princeton University | Mauzerall D.L.,Princeton University | Fiore A.M.,National Oceanic and Atmospheric Administration | Fiore A.M.,Lamont Doherty Earth Observatory
Global Change Biology | Year: 2013

Meeting the projected 50% increase in global grain demand by 2030 without further environmental degradation poses a major challenge for agricultural production. Because surface ozone (O3) has a significant negative impact on crop yields, one way to increase future production is to reduce O3-induced agricultural losses. We present two strategies whereby O3 damage to crops may be reduced. We first examine the potential benefits of an O3 mitigation strategy motivated by climate change goals: gradual emission reductions of methane (CH4), an important greenhouse gas and tropospheric O3 precursor that has not yet been targeted for O3 pollution abatement. Our second strategy focuses on adapting crops to O3 exposure by selecting cultivars with demonstrated O3 resistance. We find that the CH4 reductions considered would increase global production of soybean, maize, and wheat by 23-102 Mt in 2030 - the equivalent of a ~2-8% increase in year 2000 production worth $3.5-15 billion worldwide (USD2000), increasing the cost effectiveness of this CH4 mitigation policy. Choosing crop varieties with O3 resistance (relative to median-sensitivity cultivars) could improve global agricultural production in 2030 by over 140 Mt, the equivalent of a 12% increase in 2000 production worth ~$22 billion. Benefits are dominated by improvements for wheat in South Asia, where O3-induced crop losses would otherwise be severe. Combining the two strategies generates benefits that are less than fully additive, given the nature of O3 effects on crops. Our results demonstrate the significant potential to sustainably improve global agricultural production by decreasing O3-induced reductions in crop yields. © 2012 Blackwell Publishing Ltd. Source

Van Hooidonk R.,National Oceanic and Atmospheric Administration | Maynard J.A.,CNRS Insular Research Center and Environment Observatory | Maynard J.A.,University of North Carolina at Wilmington | Planes S.,CNRS Insular Research Center and Environment Observatory
Nature Climate Change | Year: 2013

Climate-change impacts on coral reefs are expected to include temperature-induced spatially extensive bleaching events. Bleaching causes mortality when temperature stress persists but exposure to bleaching conditions is not expected to be spatially uniform at the regional or global scale. Here we show the first maps of global projections of bleaching conditions based on ensembles of IPCC AR5 (ref.) models forced with the new Representative Concentration Pathways (RCPs). For the three RCPs with larger CO2 emissions (RCP 4.5, 6.0 and 8.5) the onset of annual bleaching conditions is associated with ∼ 510 ppm CO2 equivalent; the median year of all locations is 2040 for the fossil-fuel aggressive RCP 8.5. Spatial patterns in the onset of annual bleaching conditions are similar for each of the RCPs. For RCP 8.5, 26% of reef cells are projected to experience annual bleaching conditions more than 5 years later than the median. Some of these temporary refugia include the western Indian Ocean, Thailand, the southern Great Barrier Reef and central French Polynesia. A reduction in the growth of greenhouse-gas emissions corresponding to the difference between RCP 8.5 and 6.0 delays annual bleaching in ∼ 23% of reef cells more than two decades, which might conceivably increase the potential for these reefs to cope with these changes. © 2013 Macmillan Publishers Limited. All rights reserved. Source

Rabenold C.,National Oceanic and Atmospheric Administration
Coastal Management | Year: 2013

The U.S. coast is susceptible to a number of natural processes that can threaten lives, property, the natural environment, and, ultimately, economies. The hazards posed by these processes are likely to be exacerbated as development and redevelopment continue along the coasts and as coastal populations rise. Risk is best reduced by limiting exposure to coastal hazards. While most land use decisions are made at the local level, states can play a role in directing development away from hazard-prone places along ocean and Great Lake shorefronts through their coastal management programs. This article reports on where coastal states and territories have established no-build areas along ocean and Great Lake shorefronts to prevent unsustainable development and protect public interests. Findings suggest that roughly 75% of states with federally approved coastal management programs employ shorefront no-build areas, but that the associated laws and regulations vary considerably due largely to differences in geographic and geologic situations, regulatory frameworks, shorefront property ownership, level of existing development, and dominant uses. Laws and regulations change over time to improve effectiveness and reflect better information and new challenges. Climate change is one of the challenges that already has states reevaluating how best to protect their shorefronts. © 2013 Copyright Taylor and Francis Group, LLC. Source

Cadeddu M.P.,Argonne National Laboratory | Turner D.D.,National Oceanic and Atmospheric Administration
IEEE Transactions on Geoscience and Remote Sensing | Year: 2011

Accurate retrievals of liquid water path (LWP) from passive microwave radiometers rely on the use of radiative transfer models to describe the absorption of radiation by various atmospheric components. When clouds are present, atmospheric absorption is affected by the dielectric properties of liquid water. In this paper, we use measurements from four microwave radiometers to assess four models of the complex permittivity of water. The observations are collected at five frequencies between 23.8 and 170 GHz. The purpose of the study is to compare measurements of microwave absorption with model computations in supercooled liquid clouds that have temperatures between 0 °C and -30 °C. Models of liquid water permittivity in this temperature range suffer from a lack of laboratory measurements and are generally derived from the extrapolation of available data. An additional rationale for this work is to examine to what degree the use of different dielectric models affects the retrieval of LWP in supercooled liquid clouds. Inaccuracies in modeling the water permittivity at low temperatures are likely one of the largest sources of retrieval uncertainty in supercooled clouds, uncertainty that could offset the advantages offered by the enhanced sensitivity of channels at frequencies at and above 90 GHz relative to lower frequencies. © 2011 IEEE. Source

Gronewold A.D.,National Oceanic and Atmospheric Administration | Borsuk M.E.,Dartmouth College
Environmental Science and Technology | Year: 2010

Water quality measurement error and variability, while well-documented in laboratory-scale studies, is rarely acknowledged or explicitly resolved in most model-based water body assessments, including those conducted in compliance with the United States Environmental Protection Agency (USEPA) Total Maximum Daily Load (TMDL) program. Consequently, proposed pollutant loading reductions in TMDLs and similar water quality management programs may be biased, resulting in either slower-than-expected rates of water quality restoration and designated use reinstatement or, in some cases, overly conservative management decisions. To address this problem, we present a hierarchical Bayesian approach for relating actual in situ or model-predicted pollutant concentrations to multiple sampling and analysis procedures, each with distinct sources of variability. We apply this method to recently approved TMDLs to investigate whether appropriate accounting for measurement error and variability will lead to different management decisions. We find that required pollutant loading reductions may in fact vary depending not only on how measurement variability is addressed but also on which water quality analysis procedure is used to assess standard compliance. As a general strategy, our Bayesian approach to quantifying variability may represent an alternative to the common practice of addressing all forms of uncertainty through an arbitrary margin of safety (MOS). © 2010 American Chemical Society. Source

Danil K.,National Oceanic and Atmospheric Administration
Marine Technology Society Journal | Year: 2011

We report the details of two wildlife mortality events that were associated with underwater detonations. The detonations occurred as part of military training activities at Silver Strand Training Complex in San Diego, California. In March 2006, an underwater detonation resulted in 70 western grebes (Aechmophorus occidentalis) being killed by subsequent sequential detonations in the same training exercise. Ten of the 70 western grebes impacted were necropsied, verifying cause of death as primary blast injury. In March 2011, a time-delayed underwater detonation resulted in the death of three or possibly four long-beaked common dolphins (Delphinus capensis). While these blast events were unlikely to impact these species on a population level, underwater detonations do have the potential for population-level impacts on wildlife. Both events were accidental mortalities and the first ever documented from Navy underwater detonation training in Hawaii, Southern California, and along the U.S. East Coast. The Navy updated its underwater explosive mitigation measures after each of these mortality events to limit the potential of future mortalities by requiring sequential detonations to occur either less than 5 s or more than 30 min apart and by suspending time-delayed detonation training exercises until more robust precautionary measures can be developed. Source

Andersson A.J.,University of California at San Diego | Gledhill D.,National Oceanic and Atmospheric Administration
Annual Review of Marine Science | Year: 2013

The persistence of carbonate structures on coral reefs is essential in providing habitats for a large number of species and maintaining the extraordinary biodiversity associated with these ecosystems. As a consequence of ocean acidification (OA), the ability of marine calcifiers to produce calcium carbonate (CaCO3) and their rate of CaCO3 production could decrease while rates of bioerosion and CaCO3 dissolution could increase, resulting in a transition from a condition of net accretion to one of net erosion. This would have negative consequences for the role and function of coral reefs and the eco-services they provide to dependent human communities. In this article, we review estimates of bioerosion, CaCO3 dissolution, and net ecosystem calcification (NEC) and how these processes will change in response to OA. Furthermore, we critically evaluate the observed relationships between NEC and seawater aragonite saturation state (Omegaa). Finally, we propose that standardized NEC rates combined with observed changes in the ratios of dissolved inorganic carbon to total alkalinity owing to net reef metabolism may provide a biogeochemical tool to monitor the effects of OA in coral reef environments. © 2013 by Annual Reviews. All rights reserved. Source

Buckland S.T.,University of St. Andrews | Laake J.L.,National Oceanic and Atmospheric Administration | Borchers D.L.,University of St. Andrews
Biometrics | Year: 2010

Double-observer line transect methods are becoming increasingly widespread, especially for the estimation of marine mammal abundance from aerial and shipboard surveys when detection of animals on the line is uncertain. The resulting data supplement conventional distance sampling data with two-sample mark-recapture data. Like conventional mark-recapture data, these have inherent problems for estimating abundance in the presence of heterogeneity. Unlike conventional mark-recapture methods, line transect methods use knowledge of the distribution of a covariate, which affects detection probability (namely, distance from the transect line) in inference. This knowledge can be used to diagnose unmodeled heterogeneity in the mark-recapture component of the data. By modeling the covariance in detection probabilities with distance, we show how the estimation problem can be formulated in terms of different levels of independence. At one extreme, full independence is assumed, as in the Petersen estimator (which does not use distance data); at the other extreme, independence only occurs in the limit as detection probability tends to one. Between the two extremes, there is a range of models, including those currently in common use, which have intermediate levels of independence. We show how this framework can be used to provide more reliable analysis of double-observer line transect data. We test the methods by simulation, and by analysis of a dataset for which true abundance is known. We illustrate the approach through analysis of minke whale sightings data from the North Sea and adjacent waters. © 2009, The International Biometric Society. Source

Barnett L.A.K.,University of California at Davis | Barnett L.A.K.,University of Washington | Barnett L.A.K.,National Oceanic and Atmospheric Administration | Baskett M.L.,University of California at Davis
Ecology Letters | Year: 2015

The goals of ecosystem-based management (EBM) include protecting ecological resilience, the magnitude of a perturbation that a community can withstand and remain in a given state. As a tool to achieve this goal, no-take marine reserves may enhance resilience by protecting source populations or reduce it by concentrating fishing in harvested areas. Here, we test whether spatial management with marine reserves can increase ecological resilience compared to non-spatial (conventional) management using a dynamic model of a simplified fish community with structured predation and competition that causes alternative stable states. Relative to non-spatial management, reserves increase the resilience of the desired (predator-dominated) equilibrium state in both stochastic and deterministic environments, especially under intensive fishing. As a result, spatial management also increases the feasibility of restoring degraded (competitor-dominated) systems, particularly if combined with culling of competitors or stock enhancement of adult predators. © 2015 John Wiley & Sons Ltd/CNRS. Source