Pelland N.A.,University of Washington |
Sterling J.T.,National Marine Mammal Laboratory |
Lea M.-A.,University of Tasmania |
Bond N.A.,Joint Institute for the Study of the Atmosphere and Ocean |
And 3 more authors.
PLoS ONE | Year: 2014
Behavioral responses by top marine predators to oceanographic features such as eddies, river plumes, storms, and coastal topography suggest that biophysical interactions in these zones affect predators' prey, foraging behaviors, and potentially fitness. However, examining these pathways is challenged by the obstacles inherent in obtaining simultaneous observations of surface and subsurface environmental fields and predator behavior. In this study, migratory movements and, in some cases, diving behavior of 40 adult female northern fur seals (NFS; Callorhinus ursinus) were quantified across their range and compared to remotely-sensed environmental data in the Gulf of Alaska and California Current ecosystems, with a particular focus off the coast of Washington State (USA) - a known foraging ground for adult female NFS and where autonomous glider sampling allowed opportunistic comparison of seal behavior to subsurface biophysical measurements. The results show that in these ecosystems, adult female habitat utilization was concentrated near prominent coastal topographic, riverine, or inlet features and within 200 km of the continental shelf break. Seal dive depths, in most ecosystems, were moderated by surface light level (solar or lunar), mirroring known behaviors of diel vertically-migrating prey. However, seal dives differed in the California Current ecosystem due to a shift to more daytime diving concentrated at or below the surface mixed layer base. Seal movement models indicate behavioral responses to season, ecosystem, and surface wind speeds; individuals also responded to mesoscale eddies, jets, and the Columbia River plume. Foraging within small scale surface features is consistent with utilization of the inner coastal transition zone and habitats near coastal capes, which are known eddy and filament generation sites. These results contribute to our knowledge of NFS migratory patterns by demonstrating surface and subsurface behavioral responses to a spatially and temporally dynamic ocean environment, thus reflecting its influence on associated NFS prey species.
Evans S.M.,University of Washington |
Evans S.M.,Joint Institute for the Study of the Atmosphere and Ocean |
Marchand R.T.,University of Washington |
Marchand R.T.,Joint Institute for the Study of the Atmosphere and Ocean |
And 3 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2012
An iterative automated classification technique that combines European Centre for Medium-Range Weather Forecasts analysis data and vertically pointing millimeter wavelength cloud radar observations is used to identify commonly occurring atmospheric patterns or states around Darwin, Australia. The technique defines the atmospheric states by large-scale, synoptic variables such that, once defined, these states will be suitable to composite climate model output. Radar observations of clouds are used to test the statistical significance of each state and prompt the automated refinement of the states until each state produces a statistically stable and unique hydrometeor occurrence profile. The technique identifies eight atmospheric states: two monsoon states, two transition season states, and four dry season states. The two monsoon states can be identified as the active monsoon and the break monsoon. Among the dry season states, periods of isolated and suppressed convection can be identified. We use these states as the basis for compositing hydrometeor occurrence, precipitation rate, outgoing longwave radiation, and Madden-Julian Oscillation phase to further understand the meteorology of each state. © 2012 by the American Geophysical Union.
PubMed | Joint Institute for the Study of the Atmosphere and Ocean, University of America, University of Washington, National Marine Mammal Laboratory and University of Tasmania
Type: Journal Article | Journal: PloS one | Year: 2014
Behavioral responses by top marine predators to oceanographic features such as eddies, river plumes, storms, and coastal topography suggest that biophysical interactions in these zones affect predators prey, foraging behaviors, and potentially fitness. However, examining these pathways is challenged by the obstacles inherent in obtaining simultaneous observations of surface and subsurface environmental fields and predator behavior. In this study, migratory movements and, in some cases, diving behavior of 40 adult female northern fur seals (NFS; Callorhinus ursinus) were quantified across their range and compared to remotely-sensed environmental data in the Gulf of Alaska and California Current ecosystems, with a particular focus off the coast of Washington State (USA)--a known foraging ground for adult female NFS and where autonomous glider sampling allowed opportunistic comparison of seal behavior to subsurface biophysical measurements. The results show that in these ecosystems, adult female habitat utilization was concentrated near prominent coastal topographic, riverine, or inlet features and within 200 km of the continental shelf break. Seal dive depths, in most ecosystems, were moderated by surface light level (solar or lunar), mirroring known behaviors of diel vertically-migrating prey. However, seal dives differed in the California Current ecosystem due to a shift to more daytime diving concentrated at or below the surface mixed layer base. Seal movement models indicate behavioral responses to season, ecosystem, and surface wind speeds; individuals also responded to mesoscale eddies, jets, and the Columbia River plume. Foraging within small scale surface features is consistent with utilization of the inner coastal transition zone and habitats near coastal capes, which are known eddy and filament generation sites. These results contribute to our knowledge of NFS migratory patterns by demonstrating surface and subsurface behavioral responses to a spatially and temporally dynamic ocean environment, thus reflecting its influence on associated NFS prey species.
Chang B.X.,University of Washington |
Chang B.X.,Princeton University |
Chang B.X.,Joint Institute for the Study of the Atmosphere and Ocean |
Rich J.R.,Brown University |
And 6 more authors.
Limnology and Oceanography | Year: 2014
The three major oxygen deficient zones (ODZs) of the world oceans (eastern tropical North and South Pacific (ETNP and ETSP, respectively), and Arabian Sea (AS) host the vast majority of pelagic fixed nitrogen (N) loss and up to half of total marine N loss. The input of organic matter is an important control on the absolute and relative importance of the two main pathways of N removal (denitrification and anammox). We investigated the response of N loss in the ETSP and AS ODZs to additions of organic matter in the form of glucose and naturally derived dissolved and particulate organic matter (DOM and POM, respectively). In the ETSP ODZ, the addition of glucose stimulated denitrification (1.6-fold increase after 5 d) but not anammox (14-fold decrease after 5 d). In the AS ODZ, only POM, not DOM, significantly increased rates of denitrification at the base of the oxycline (5.4-6.4-fold increase after 2 d), but not at the secondary nitrite maximum. These results suggest that denitrification was generally limited by organic matter supply at the time of this study in both the ETSP and AS ODZs, although the lability of the organic matter supplied was important. Interestingly, 15N2 produced in ETSP and AS incubations was not binomially distributed relative to the reactants after the influence of anammox was taken into account, suggesting an unknown production mechanism or pathway of N removal. © 2014, by the Association for the Sciences of Limnology and Oceanography, Inc.
Giddings S.N.,University of Washington |
Giddings S.N.,University of California at San Diego |
Maccready P.,University of Washington |
Hickey B.M.,University of Washington |
And 7 more authors.
Journal of Geophysical Research: Oceans | Year: 2014
Harmful algal blooms (HABs) pose a significant threat to human and marine organism health, and negatively impact coastal economies around the world. An improved understanding of HAB formation and transport is required to improve forecasting skill. A realistic numerical simulation of the US Pacific Northwest region is used to investigate transport pathways from known HAB formation hot spots, specifically for Pseudo-nitzschia (Pn), to the coast. We show that transport pathways are seasonal, with transport to the Washington (WA) coast from a northern source (the Juan de Fuca Eddy) during the summer/fall upwelling season and from a southern source (Heceta Bank) during the winter/early spring due to the predominant wind-driven currents. Interannual variability in transport from the northern source is related to the degree of wind intermittency with more transport during years with more frequent relaxation/downwelling events. The Columbia River plume acts to mitigate transport to the coast as the plume front blocks onshore transport. The plume's influence on alongshore transport is variable although critical in aiding transport from the southern source to the WA coast via plume entrainment. Overall transport from our simulations captures most observed Pn HAB beach events from 2004 to 2007 (characterized by Pseudo-nitzschia cell abundance); however, numerous false positives occur. We show that incorporating phytoplankton biomass results from a coupled biogeochemical model reduces the number of false positives significantly and thus improves our Pn HAB predictions. Key Points Potential PNW HAB transport is seasonal, consistent with regional currents Transport is blocked by the Columbia River plume unless entrainment occurs A coupled hydrodynamic-biological model can predict PNW Pn HAB transport paths © 2014. American Geophysical Union. All Rights Reserved.
Shi L.,National Oceanic and Atmospheric Administration |
Matthews J.L.,National Oceanic and Atmospheric Administration |
Matthews J.L.,North Carolina State University |
Ho S.-P.,University Corporation for Atmospheric Research |
And 2 more authors.
Remote Sensing | Year: 2016
A project for deriving temperature and humidity profiles from High-resolution Infrared Radiation Sounder (HIRS) observations is underway to build a long-term dataset for climate applications. The retrieval algorithm development of the project includes a neural network retrieval scheme, a two-tiered cloud screening method, and a calibration using radiosonde and Global Positioning System Radio Occultation (GPS RO) measurements. As atmospheric profiles over high surface elevations can differ significantly from those over low elevations, different neural networks are developed for three classifications of surface elevations. The significant impact from the increase of carbon dioxide in the last several decades on HIRS temperature sounding channel measurements is accounted for in the retrieval scheme. The cloud screening method added one more step from the HIRS-only approach by incorporating the Advanced Very High Resolution Radiometer (AVHRR) observations to assess the likelihood of cloudiness in HIRS pixels. Calibrating the retrievals with radiosonde and GPS RO reduces biases in retrieved temperature and humidity. Except for the lowest pressure level which exhibits larger variability, the mean biases are within ±0.3 °C for temperature and within ±0.2 g/kg for specific humidity at standard pressure levels, globally. Overall, the HIRS temperature and specific humidity retrievals closely align with radiosonde and GPS RO observations in providing measurements of the global atmosphere to support other relevant climate dataset development. © 2016 by the authors.
Carter B.R.,Joint Institute for the Study of the Atmosphere and Ocean |
Carter B.R.,National Oceanic and Atmospheric Administration |
Frolicher T.L.,ETH Zurich |
Dunne J.P.,Princeton University |
And 3 more authors.
Global Biogeochemical Cycles | Year: 2016
We use a large initial condition suite of simulations (30 runs) with an Earth system model to assess the detectability of biogeochemical impacts of ocean acidification (OA) on the marine alkalinity distribution from decadally repeated hydrographic measurements such as those produced by the Global Ship-Based Hydrographic Investigations Program (GO-SHIP). Detection of these impacts is complicated by alkalinity changes from variability and long-term trends in freshwater and organic matter cycling and ocean circulation. In our ensemble simulation, variability in freshwater cycling generates large changes in alkalinity that obscure the changes of interest and prevent the attribution of observed alkalinity redistribution to OA. These complications from freshwater cycling can be mostly avoided through salinity normalization of alkalinity. With the salinity-normalized alkalinity, modeled OA impacts are broadly detectable in the surface of the subtropical gyres by 2030. Discrepancies between this finding and the finding of an earlier analysis suggest that these estimates are strongly sensitive to the patterns of calcium carbonate export simulated by the model. OA impacts are detectable later in the subpolar and equatorial regions due to slower responses of alkalinity to OA in these regions and greater seasonal equatorial alkalinity variability. OA impacts are detectable later at depth despite lower variability due to smaller rates of change and consistent measurement uncertainty. ©2016. The Authors.
News Article | October 4, 2016
Blooms of algae along the West Coast of the U.S. in 2015 were bigger and more toxic than ever before, contaminating food webs and closing fisheries from southern California to as far north as British Columbia, in Canada. Now, a new study links them to elevated ocean temperatures, with algae growth spurred by a mysterious patch of warmer-than-average ocean that scientists first noted years earlier and had dubbed "the warm blob." The warm blob, which first appeared in 2013 and hung around into 2014, helped one species of toxic algae — Pseudo-nitzschia australis — increase in unprecedented numbers and expand farther north than was previously possible, with devastating effects on a wide range of marine life. [Yuck! Photos of 'Rock Snot' Algae Infestations] Toxic algae events that are serious enough to merit fishery closures occur off the coasts of Washington and Oregon every three to five years, but the 2015 bloom was the largest by far, according to Ryan McCabe, the study's lead author and a researcher at the University of Washington's Joint Institute for the Study of the Atmosphere and Ocean in Seattle. "And our results show that it was connected to the unusual ocean conditions,” McCabe said in a statement. The warm blob began as a large, circular zone in the Pacific Ocean, about 1,000 miles (1,600 kilometers) long; 1,000 miles wide and more than 300 feet (90 meters) deep, spreading out along the coast and moving closer to shore in 2015. This infusion of warm water accompanied currents carrying nutrients from the deep sea, enabling P. australis to reproduce faster, the researchers discovered. P. australis produces a neurotoxin called domoic acid, which can cause seizures and gastrointestinal distress, and is sometimes lethal. When shellfish and small fish like anchovies eat the algae, they can transmit the toxin to animals that feed on them — including people. And because P. australis blooms were more widespread in 2015, more marine mammals were vulnerable to the impacts of the toxic algae, the researchers said. Scientists have long studied the cyclical growth of algae populations in coastal waters, building a 25-year record that tracks the ebb and flow of the algae and the toxins they impart to local marine wildlife. By establishing a link between warmer oceans and increased toxic algal growth, the new study hints that rising global temperatures could make deadly blooms a more common occurrence. "Species like Pseudo-nitzschia are extremely well poised to take advantage of background warming," McCabe said. "Pseudo-nitzschia are always out there along our coast. The fact that they are almost engineered to take advantage of situations like this — warm temperatures and low nutrients — that is concerning." The study was published online Sept. 20 in the journal Geophysical Research Letters.
News Article | September 29, 2016
Last year, a massive toxic algae bloom swept the West Coast, resulting in record-breaking levels of a potentially deadly brain-damaging chemical and closing fisheries from California to British Columbia. Since then, scientists have been investigating the causes of the event — and now, a group of researchers think they’ve figured out how the event, which they term “unprecedented,” happened. The algae bloom was facilitated by an unusual “blob” of warm water lurking in the Pacific Ocean at that time, the scientists say. And while the blob itself may have been largely brought on by weird but natural ocean and atmospheric variations, climate change may result in similar conditions cropping up in the future — and hence, more frequent toxic algal blooms. The work was published in Geophysical Research Letters. Algae blooms aren’t uncommon off the West Coast. In fact, they tend to happen around the same time every year, said the new study’s lead author Ryan McCabe, a research scientist at the University of Washington’s Joint Institute for the Study of the Atmosphere and Ocean. Each spring, there’s a shift in winds and other atmospheric and oceanic conditions that causes deep, cold, nutrient-rich water to rise up from the seafloor to the surface of the ocean in a process known as “upwelling.” Having both lots of nutrients and sunlight at the water’s surface creates perfect conditions for algae to start multiplying. Normally, these algae blooms are composed of many different species of phytoplankton, and most of them are not harmful. The difference in 2015 is that a single toxic species — Pseudo-nitzschia australis, which produces a neurotoxin called domoic acid — dominated the bloom, an event that McCabe says was “absolutely abnormal.” He and his colleagues are arguing that the strange warm blob is what made Pseudo-nitzchia’s take-over possible. The blob first showed up in the Northeast Pacific in the fall of 2013. Hundreds of miles wide and about 300 feet deep, the blob’s waters were nearly 3 degrees Celsius warmer than what’s typical for the region. Scientists believe it persisted through the end of 2015 before fading away, although more recent research suggests that a remnant of the blob may still be lurking below the surface of the ocean. While the appearance of the blob is still not completely understood, scientists believe it may have marked the beginning of a shift in a natural oceanic climate swing known as the Pacific Decadal Oscillation. It’s somewhat like a much longer-term version of the El Niño and La Niña cycle, phasing between warm and cool extremes in different parts of the Pacific. Regardless of the cause, the unusually warm blob was a perfect set-up for the toxic algae. In the winter, before the upwelling starts along the coast, nutrients tend to be scarce at the ocean’s surface. But Pseudo-nitzschia are particularly well-suited to dealing with nutrient-poor conditions, according to McCabe, and they also grow much faster in warm water. As a result, they essentially were able to out-compete other species before the upwelling even began, leaving them poised for a massive bloom. “We had a couple of samples off the coast before the spring transition, and those samples already had toxins in them,” McCabe noted. “And that is highly unusual. But because those few samples had those toxins, we said, ‘Oh wow, we already had a toxic species out there simply waiting for a big pulse of nutrients to explode.’” Indeed, sampling off the coast indicated that concentrations of both Pseudo-nitzschia and the neurotoxin it produces peaked in early May, and did not drop off until later in the summer, when additional upwelling finally dragged other, less harmful, species up from deeper parts of the ocean. To further investigate their theory, the researchers went back and looked at records from previous warm periods off the West Coast, resulting from El Nino events or other temporary climate shifts. The literature suggests that increases in Pseudo-nitzschia do seem to track these kinds of warming events. “It seems as though there is this relationship with warming, and what we saw in 2015 was an extreme case of that,” said Stephanie Moore, a visiting scientist at NOAA’s Northwest Fisheries Science Center and a project scientist with the University Corporation for Atmospheric Research, who was not involved with the new study. While 2015’s warm anomaly may have been the result of natural climate variability, the researchers have warned that future climate change could result in similar conditions, setting up the West Coast for more frequent toxic blooms. “We really are looking at this event here in 2015 as a window into the future of what we might expect for conditions to look like,” McCabe said. That said, McCabe added that temperature isn’t the only important factor when it comes to the occurrence of algae blooms. And Moore pointed out that future climate change is expected to influence all kinds of other variables that may contribute to changes in plankton behavior. For instance, we may see changes in wind patterns, which are instrumental in starting the upwelling process each spring. These patterns may be complemented, or perhaps balanced out to a certain extent, by increasing stratification of the oceans — that is, the formation of warm and cold layers of water at different depths which sometimes get stuck that way, making upwelling more difficult. And changes in the types and concentrations of nutrients that go into the ocean in the first place may also change as coastal populations increase. McCabe noted that changes in nutrient runoff are likely to be one of the biggest factors besides temperature affecting the severity of future algae blooms.
News Article | November 18, 2015
In spite of the coordinated attacks in Paris on Nov. 13, the United Nations Framework Convention on Climate Change (UNFCCC) will proceed as scheduled on Nov. 30 to Dec. 11, 2015. One of the proposals to combat climate change comes from the University of Washington's Joint Institute for the Study of the Atmosphere and Ocean (JISAO) which believes that climate engineering techniques can be humanity's weapon against the continuing increase in temperature and extreme weather worldwide. More specifically, JISAO scientists believe that misting the clouds with saltwater, a cloud reflectivity modification technique would help in brightening up the clouds and aid it with reflecting sunlight back to lessen amount of heat that will enter through the atmosphere. "If you can reflect away some of that radiation... you will cool the planet," Tom Ackerman, an atmospheric scientist at JISAO said. Ackerman directs this specific research on climate change at JISAO. "People have this sort of innate response that somehow we're tinkering with Mother Nature, and we shouldn't be doing that," Ackerman said, explaining why there have been oppositions to such plans. However, he also said that humans already emit carbon dioxide into the atmosphere due to fossil fuel use. Clive Hamilton, an Australian ethicist, argued against using Geoengineering as a remedy to climate problems. He believes that the humanity's attitude is what needs to be changed in order to reach a long term solution. "Technofixes-technical solutions to social problems-are appealing when we are unwilling to change ourselves and our social institutions... There is a long history of technological interventions entrenching the behaviors that created the problem," he wrote in an article in March. The Geoengineering techniques for climate change will be discussed in the Paris Climate Change Conference as a Plan B, with Plan A involving agreements to reduce carbon emissions in developing countries.