Karamchandani P.,AER Inc. |
Vijayaraghavan K.,AER Inc. |
Chen S.-Y.,AER Inc. |
Balmori-Bronson R.,AER Inc. |
Atmospheric Pollution Research | Year: 2010
The Community Multiscale Air Quality Model (CMAQ) is a comprehensive three-dimensional "one-atmosphere" air quality model that is now routinely used to address urban, regional-scale and continental-scale multi- pollutant issues such as ozone, particulate matter, and air toxics. Several updates have been made to CMAQ by the scientific community to enhance its capabilities and to provide alternative science treatments of some of the relevant governing processes. The Advanced Modeling System for Transport, Emissions, Reactions and Deposition of Atmospheric Matter (AMSTERDAM) is one such adaptation of CMAQ that adds an Advanced Plume-in-grid Treatment (APT) for resolving sub-grid scale processes associated with emissions from elevated point sources. It also incorporates a state-of-the-science alternative treatment for aerosol processes based on the Model of Aerosol Dynamics, Reaction, Ionization and Dissolution (MADRID). AMSTERDAM is configured to provide flexibility to the model user in selecting options for the new science modules. This paper describes the parallelization of AMSTERDAM to make it a practical tool for plume-in-grid (PinG) treatment of a large number of point sources, and presents results from its application to the central and eastern United States for summer and winter periods in 2002. Over 150 coal-fired power plants in the domain with high emissions of sulfur dioxide (SO2) and nitrogen oxides (NOX) were selected for PinG treatment in the CMAQ-MADRID-APT configuration of AMSTERDAM used for this application. Although both model configurations (grid-only and PinG) give similar model performance results (an aggregate measure of model skill), the results show significant differences between the two versions in the specific nature of the predicted spatial distribution of ozone and PM2.5 concentrations. These differences can be important in determining source contributions to ambient concentrations. A companion paper examines the differences in the predicted contributions of hypothetical source regions from the two configurations of the model. © Author(s) 2010.
Matsui H.,University of New Hampshire |
Darrouzet F.,Belgian Institute for Space Aeronomy |
Goldstein J.,Southwest Research Institute |
Puhl-Quinn P.A.,AER Inc. |
And 5 more authors.
Annales Geophysicae | Year: 2012
In this event study, small-scale fluctuations in plasmaspheric plumes with time scales of ∼10 s to minutes in the spacecraft frame are examined. In one event, plasmaspheric plumes are observed by Cluster, while IMAGE measured density enhancement at a similar location. Fluctuations in density exist in plumes as detected by Cluster and are accompanied by fluctuations in magnetic fields and electric fields. Magnetic fluctuations are transverse and along the direction of the plumes. The E/B ratio is smaller than the Alfvén velocity. Another similar event is briefly presented. We then consider physical properties of the fluctuations. Alfvén mode modulated by the feedback instability is one possibility, although non-local generation is likely. It is hard to show that the fluctuations represent a fast mode. Interchange motion is possible due to the consistency between measurements and expectations. The energy source could be a pressure or density gradient in plasmaspheric plumes. When more events are accumulated so that statistical analysis becomes feasible, this type of study will be useful to understand the time evolution of plumes. © Author (s) 2012.
Matsui H.,University of New Hampshire |
Puhl-Quinn P.A.,AER Inc. |
Bonnell J.W.,University of California at Berkeley |
Farrugia C.J.,University of New Hampshire |
And 5 more authors.
Journal of Geophysical Research: Space Physics | Year: 2010
Storm-time electric fields in the inner magnetosphere measured by Cluster are reported in this study. First, we show two events around the time when Dst index is at a minimum. The electric field possibly related to subauroral ion drifts and/or undershielding is measured inside the inner edge of the electron plasma sheet in the eveningside. For the second event observed in the nightside, the electric field is partly related to dipolarization and is considered as inductive. An electric field without coincident magnetic signatures is also observed. Spatial coherence of the electric field is not large when we check multispacecraft data. It is inferred that the electric field in the magnetotail penetrates inside the region 1 current, while it is not clear about the electric field within the region 2 current from our data. Then superposed epoch analyses using 71 storms are performed. Electric fields at R = 3.5-6RE and less than 25 degrees of magnetic latitudes are enhanced around the minimum Dst at all magnetic local times. Electric fields during the recovery phase decay on a time scale shorter than that of Dst index, which could be interpreted in terms of the relation between electric field and ring current during that storm phase. AC electric fields are generally larger than DC electric fields, indicating that the former component might play some role in accelerating ring current particles. These results will be useful to update our empirical electric field model. Copyright 2010 by the American Geophysical Union.
Milikh G.M.,University of Maryland University College |
Mishin E.,Air Force Research Lab |
Galkin I.,University of Massachusetts Lowell |
Vartanyan A.,University of Maryland University College |
And 2 more authors.
Geophysical Research Letters | Year: 2010
New results of the DMSP satellite and HAARP digisonde observations during HF heating at the High-Frequency Active Auroral Program (HAARP) facility are described. For the first time, the DMSP satellites detected significant ion outflows associated with 10-30% density enhancements in the topside ionosphere above the heated region near the magnetic zenith. In addition, coincident high-cadence skymaps from the HAARP digisonde reveal field-aligned upward plasma flows inside the F-peak region. The SAMI2 2 model calculations are in fair agreement with the observations. Copyright © 2010 by the American Geophysical Union.
Mao H.,New York University |
Talbot R.,University of Houston |
Hegarty J.,AER Inc. |
Koermer J.,Plymouth State University
Atmospheric Chemistry and Physics | Year: 2012
Long-term continuous measurements of gaseous elemental mercury (Hg0), reactive gaseous mercury (RGM), and particulate phase mercury (HgP) were conducted at coastal (Thompson Farm, denoted as TF), marine (Appledore Island, denoted as AI), and elevated inland rural (Pac Monadnock, denoted as PM) monitoring sites of the AIRMAP Observing Network. Diurnal, seasonal, annual, and interannual variability in Hg0, RGM, and HgP from the three distinctly different environments were characterized and compared in Part 1. Here in Part 2 relationships between speciated mercury (i.e., Hg0, RGM, and HgP) and climate variables (e.g., temperature, wind speed, humidity, solar radiation, and precipitation) were examined. The best point-to-point correlations were found between Hg0 and temperature in summer at TF and spring at PM, but there was no similar correlation at AI. Subsets of data demonstrated regional impacts of episodic dynamic processes such as strong cyclonic systems on ambient levels of Hg0 at all three sites, possibly through enhanced oceanic evasion of Hg0. A tendency of higher levels of RGM and HgP was identified in spring and summer under sunny conditions in all environments. Specifically, the 10th, 25th, median, 75th, and 90th percentile mixing ratios of RGM and HgP increased with stronger solar radiation at both the coastal and marine sites. These metrics decreased with increasing wind speed at AI indicating enhanced loss of RGM and HgP through deposition. RGM and HgP levels correlated with temperature positively in spring, summer and fall at the coastal and marine locations. At the coastal site relationships between RGM and relative humidity suggested a clear decreasing tendency in all metrics from <40% to 100% relative humidity in all seasons especially in spring, compared to less variability in the marine environment. The effect of precipitation on RGM at coastal and marine locations was similar. At the coastal site, RGM levels were a factor of 3-4 to two orders of magnitude higher under dry conditions than rainy conditions in all seasons. In winter RGM mixing ratios appeared to be mostly above the limit of detection (LOD) during snowfalls suggesting less scavenging efficiency of snow. Mixing ratios of HgP at the coastal and marine sites remained above the LOD under rainy conditions. Precipitation had negligible impact on the magnitude and pattern of diurnal variation of HgP in all seasons in the marine environment. © Author(s) 2012. CC Attribution 3.0 License.
Gangopadhyay A.,University of Massachusetts Dartmouth |
Bharat Raj G.N.,Indian Institute of Science |
Chaudhuri A.H.,AER Inc. |
Babu M.T.,National Institute of Oceanography of India |
Sengupta D.,Indian Institute of Science
Geophysical Research Letters | Year: 2013
We present evidence that the springtime western boundary current (WBC) in the Bay of Bengal is a continuous northward-flowing current from about 12°N to 17°N, which then separates from the coast at around 18°N. We first revisit a hydrographic data set collected in 1987 from a potential vorticity perspective, and then analyze absolute dynamic height maps from satellite altimeters during the period 2000-2010. The altimetric maps suggest that the mean configuration of the WBC is that of an intense current with two anticyclonic eddies on the offshore side, which are part of the basin-wide anticyclonic circulation. The WBC consistently separates from the coast at around 18°N in all years between 2000 and 2010. The path of the eastward-flowing mean stream after separation appears to be consistent with isolines of f/H and with Ertel's potential vorticity, based on an analysis of the hydrographic data from 1987. © 2013 American Geophysical Union. All Rights Reserved.
Jimenez C.,French National Center for Scientific Research |
Prigent C.,French National Center for Scientific Research |
Catherinot J.,French National Center for Scientific Research |
Rossow W.,City College of New York |
And 2 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2012
Land surface skin temperature (LST) estimates from the International Satellite Cloud Climatology Project (ISCCP) are compared with estimates from the satellite instruments AIRS and MODIS, and in situ observations from CEOP. ISCCP has generally slightly warmer nighttime LSTs compared with AIRS and MODIS (global) and CEOP (at specific sites). Differences are smaller than 2K, similar to other reported biases between satellite estimates. Larger differences are found in the day-time LSTs, especially for those regions where large LST values occur. Inspection of the AIRS and ISCCP brightness temperatures at the top of the atmosphere (TOA-BT) reveals that where the LSTs differ so too do the TOA-BT values. Area-averaged day-time TOA-BT values can differ as much as 5K in very dry regions. This could be related to differences in sensor calibration, but also to the large LST gradients at the AIRS mid-day overpass that likely amplify the impact of sensor mismatches. Part of the studied LST differences are also explained by discrepancies in the AIRS and ISCCP characterization of the surface (emissivity) and the atmosphere (water vapor). ISCCP calibration procedures are currently being revised to account better for sensor spectral response differences, and alternative atmospheric and surface data sets are being tested as part of a complete ISCCP reprocessing. This is expected to result in an improved ISCCP LST record. Copyright 2012 by the American Geophysical Union.
Yamamoto K.K.,U.S. Army |
Vecherin S.N.,U.S. Army |
Wilson D.K.,U.S. Army |
Borden C.T.,AER Inc. |
And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012
Effective use of passive and active sensors for surveillance, security, and intelligence must consider terrain and atmospheric effects on the sensor performance. Several years ago, U.S. Army ERDC undertook development of software for modeling environmental effects on target signatures, signal propagation, and battlefield sensors for many signal modalities (e.g., optical, acoustic, seismic, magnetic, radio-frequency, chemical, biological, and nuclear). Since its inception, the software, called Environmental Awareness for Sensor and Emitter Employment (EASEE), has matured and evolved significantly for simulating a broad spectrum of signal-transmission and sensing scenarios. The underlying software design involves a flexible, object-oriented approach to the various stages of signal modeling from emission through processing into inferences. A sensor placement algorithm has also been built in for optimizing sensor selections and placements based on specification of sensor supply limitations, coverage priorities, and wireless sensor communication requirements. Some recent and ongoing enhancements are described, including modeling of active sensing scenarios and signal reflections, directivity of signal emissions and sensors, improved handling of signal feature dependencies, extensions to realistically model additional signal modalities such as infrared and RF, and XML-based communication with other calculation and display engines.
Scott G.,AER Inc. |
Smith L.M.,AER Inc.
SPE Production and Operations Symposium, Proceedings | Year: 2013
In multiple wells in the Williston Basin of North Dakota, introduction of a new reaming tool utilized for dedicated reaming and reaming-while-drilling operations has been introduced successfully in over 140 wells. This new tool has increased the percentage of packers going to total depth (TD) in a single trip in Williston Basin wells, where it is critical that wellbore condition enables multiple packers to be run and set at TD in a timely fashion in a single trip. Additionally enhanced packer design, in combination with a better understanding of well bore conditions as well as improved torque and drag reductions, has led to additional field successes. Historically this has not been the case in a number of wells, and information will be provided on certain of those instances. The reaming tools are currently bring used in reaming-while-drilling scenarios to eliminate the need for a dedicated reamer run in each well; this saves two to three rig days. These tools can be built as steel or non-magnetic (non-mag) tools; hence, they can be run anywhere in the BHA plus be used to drill out. They reduce spiraling in the well bore, thereby reducing the risk of sticking the liner assembly before reaching TD. Operators are 100% successful with packers going to TD when using this technology. In addition, current BHA modeling techniques and field use documents that use of the tools presents no significant steerability issues and no loss in penetration rate while still enabling subsequent installation of multiple packers. This proved critical in these North Dakota wells, where the application can require running as many as 35 swell packers to bottom. Also provided is input on certain packer designs that can be used in combination with these new reaming technologies to improve the chances for going to TD in a single run. Finally, the paper addresses the economic impact of this reamer application in what can be a half-million dollar operation per well, and notes the on-going progress of reaming-while-drilling efforts to date. Copyright 2013, Society of Petroleum Engineers.
Beck D.R.,Michigan Technological University |
O'Malley S.M.,AER Inc.
Journal of Physics B: Atomic, Molecular and Optical Physics | Year: 2010
We complete the development of a relativistic energy-dependent efficient method by which important pair-correlation effects associated with open subshells can be incorporated into the relativistic configuration interaction (RCI) methodology. We apply this to predict the positions of the 4f 66s2 5DJ levels of Sm I. Relative to 5D1, we predict 5D0 lies at-1613 cm-1 and 5D4 at 6589 cm-1. For 5D2 and 5D3, we are 22 cm -1 and 123 cm-1 below the observed difference, respectively. We also calculate magnetic dipole transition rates among these levels and the ground-state 7FJ levels, which may be of interest to future parity nonconservation studies. © 2010 IOP Publishing Ltd.