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Atmospheric Modeling Division Publications: 2001
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This page lists publication titles, citations and abstracts produced by NERL's Atmospheric Modeling Division for the year 2001, organized by Publication Type. Your search has returned
27 Matching Entries.
See also Atmospheric Modeling Division citations with abstracts:
1999,
2000,
2001,
2002,
2003,
2004,
2005,
2006,
2007,
2008
Technical Information Manager: Liz Hope - (919) 541-2785 or hope.elizabeth@epa.gov
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Presented/Published |
| BOOK CHAPTER |
Description of Atmospheric Transport Processes in Eulerian Air Quality Models |
01/01/2001
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Byun, D. W. Description of Atmospheric Transport Processes in Eulerian Air Quality Models. Mesoscale Atmospheric Dispersion: Advances in Air Pollution Series. WIT Press, Boston, MA, 289-341, (2001).
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Key differences among many types of air quality models are the way atmospheric advection and turbulent diffusion processes are treated. Gaussian models use analytical solutions of the advection-diffusion equations. Lagrangian models use a hypothetical air parcel concept effectively removing the need for explicit treatment of transport processes. Eulerian models require solution of the advection-diffusion equation using some numerical techniques. Here, modeling techniques for atmospheric transport processes (except for the subgrid scale cloud mixing) in Eulerian air quality models are presented. First, the presentation describes computational coordinates for atmospheric studies, diagnostic and prognostic meteorological modeling techniques, and assumptions on atmospheric dynamics. Then, it emphasizes use of the flux-form formulations that ensure conservation of mass during the transport processes. Instead of dwelling on specific numerical algorithms or comparison among them, it provides general descriptions of numerical techniques for the transport processes used in Eulerian air quality models.
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| JOURNAL |
Development of An Aggregation and Episode Selection Scheme to Support the Models-3 Community Multiscale Air Quality Model |
02/01/2001
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Cohn, R. D., B. K. Eder, S. K. LeDuc, AND R. L. Dennis. Development of An Aggregation and Episode Selection Scheme to Support the Models-3 Community Multiscale Air Quality Model. JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY 40(2):210-228, (2001).
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The development of an episode selection and aggregation approach, designed to support distributional estimation of use with the Models-3 Community Multiscale Air Quality (CMAQ) model, is described. The approach utilized cluster analysis of the 700-hPa east-west and north-south wind field components over the time period of 1984-92 to define homogeneous meteorological clusters. Alternative schemes were compared using relative efficiencies and meteorological considerations. An potimal scheme was defined to include 20 clusters 9five per season), and a stratified sample of 40 events was selected from the 20 clusters using a systematic sampling technique. The light-extinction coefficient, which provides a measure of visibility, was selected as the primary evaluative parameter for two reasons. First, this parameter can serve as s surrogate for particulate matter with diameter of less than 2.5 m, for which few observational data exists. Second, of the air quality parameters simulated by CMAQ, this visibility parameter has one of the most spatially and temporally comprehensive observational datasets. Results suggested that the approach reasonably characterizes synoptic-scale flow patterns and leads to strata that explain the variation tin extinction coefficient and other parameters (temperature and relative humidity) used in this analysis, and therefore the approach can be used to achieve improved estimates of these parameters relative to estimates obtained using other methods. Moreover, during seasonally based clusters further improves the ability of the clusters to explain the variation in these parameters and therefore leads to more precise estimates.
The work reported in this document was funded wholly or in part by the U.S. Environmental Protection Agency. The document has been reviewed and approved by the agency for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
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| JOURNAL |
Consistent Use of the Kalman Filter in Chemical Transport Models (Ctms) for Deducing Emissions |
01/01/2001
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Gilliland, A. B. Consistent Use of the Kalman Filter in Chemical Transport Models (Ctms) for Deducing Emissions. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 106(D16):17,939-17,952, (2001).
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Past research has shown that emissions can be deduced using observed concentrations of a chemical, a Chemical Transport Model (CTM), and the Kalman filter in an inverse modeling application. An expression was derived for the relationship between the "observable" (i.e., the concentration) and the "internal" state (i.e., emissions) in order to implement the Kalman filter with a CTM for emission deduction. Only the final version of the equation is usually presented when the results are published from this type of application. A critical assumption in the derivation is that the modeled chemical concentrations are initially the same as observed at the monitor locations. An alternative implementation of the method that includes the modeled and observed initial concentrations must be applied when this assumption cannot be justified. However, the alternative formula answers a fundamentally different question that may not provide the information usually intended for inverse modeling studies.
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| JOURNAL |
Development of a Land-Surface Model Part I: Application in a Mesoscale Meteorology Model |
09/04/2001
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Xiu, A. AND J. A. Pleim. Development of a Land-Surface Model Part I: Application in a Mesoscale Meteorology Model. JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY 40(2):192-209, (2001).
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Parameterization of land-surface processes and consideration of surface inhomogeneities are very important to mesoscale meteorological modeling applications, especially those that provide information for air quality modeling. To provide crucial, reliable information on the diurnal evolution of the planetary boundary layer (PBL) and its dynamic characteristics, it is necessary in a mesoscale model to include a land surface parameterization that simulates the essential physics processes and is computationally efficient.
A land surface model is developed and implemented in the Fifth Generation Penn State/NCAR Mesoscale Model (MM5) to enable MM5 to respond to changing soil moisture and vegetation conditions. This land surface model includes explicit soil moisture, which is based on the Interaction Soil Biosphere Atmosphere (ISBA) model and three pathways for evaporation including soil evaporation, canopy evaporation, and vegetative evapotranspiration. The stomatal conductance, leaf to canopy scaling, and surface moisture parameterizations are newly developed based on a variety of sources in the current literature. Also, a processing procedure for gridding soil and vegetation parameters and simulating seasonal growth has been developed. MM5 with the land surface model is tested and evaluated against observations and the "standard" MM5, which uses a simple surface moisture availability scheme to estimate the soil wetness then the latent heat flux, for two cases from the First International Satellite Land Surface Climatology Project Field Experiment (FIFE). The evaluation analysis focuses primarily on surface fluxes of heat and moisture, near surface temperature, soil temperature, PBL height, and vertical temperature profiles. A subsequent article will describe extensions of this model to simulate chemical dry deposition.
The U.S. Environmental Protection Agency through its Office of Research and Development funded the research described here under cooperative agreement CR-823628 to the MCNC-Environmental Programs. It has been subjected to agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
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| JOURNAL |
A Coupled Land-Surface and Dry Deposition Model and Comparison to Field Measurements of Surface Heat, Moisture, and Ozone Fluxes |
01/01/2001
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Pleim, J. A. A Coupled Land-Surface and Dry Deposition Model and Comparison to Field Measurements of Surface Heat, Moisture, and Ozone Fluxes. JOURNAL OF WATER, AIR, AND SOIL POLLUTION Focus 1(5/6):243-252, (2001).
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We have developed a coupled land-surface and dry deposition model for realistic treatment of surface fluxes of heat, moisture, and chemical dry deposition within a comprehensive air quality modeling system. A new land-surface model (LSM) with explicit treatment of soil moisture and evapotranspiration and an indirect soil moisture nudging scheme has been added to a mesoscale meteorology model. The new dry deposition model uses the same aerodynamic and bulk stomatal resistances computed for evapotranspiration in the LSM. This provides consistent land-surface and boundary layer properties across the meteorological and chemical components of the system. The coupled dry deposition model also has the advantage of veing able to respond to changing soil moisture and vegetation conditions. Modeled surface fluxes of sensible and latent heat as well as ozone dry deposition velocities were compared to two field experiments: a soybean field in Kentucky during summer of 1995 and a mixed forest in the Adirondacks of New York in July 1998.
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| JOURNAL |
Sensitivity Analysis and Evaluation of Microfaco: A Microscale Motor Vehicle Emission Factor Model for CO Emissions |
06/01/2001
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Singh, R. B., A. H. Huber, AND J. N. Braddock. Sensitivity Analysis and Evaluation of Microfaco: A Microscale Motor Vehicle Emission Factor Model for CO Emissions. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION 51(7):1087-1099, (2001).
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The United States Environmental Protection Agency's National Exposure Research Laboratory has initiated a project to improve the methodology for modeling human exposure to motor vehicle emissions. The overall project goal is to develop improved methods for modeling the source through the air pathway to human exposure in significant microenvironments of exposure. The PART models (used in the United States, except California) and EMFAC models (used in California only) used to estimate emissions are suitable only for regional (county) scale modeling and emission inventories because of their dependence on aggregated vehicle-miles-traveled data. These emission models are not designed to estimate real-time emissions needed for human exposure studies near roadways. Therefore, there is a need to develop site-specific real-time emission factor models for PM emissions.
A microscale emission factor model for predicting site-specific real-time motor vehicle particulate matter (MicroFacPM) emissions for TSP, PM10 and PM2.5 has been developed. It uses site-specific available information on the vehicle fleet composition. The algorithm used to calculate emission factors in MicroFacPM is disaggregated based on the site-specific vehicle fleet. The emission factors are calculated from a real-time fleet, rather than from a fleet-wide average estimated by a vehicle-miles-traveled weighting of the emission factors for different vehicle classes. MicroFacPM requires input information necessary to characterize the site-specific real-time fleet being modeled. Other variables required are average vehicle speed, time and day of the year, ambient temperature and relative humidity.
The U.S. Environmental Protection Agency through its Office of Research and Development funded the research described here. This manuscript has been subjected to Agency review and approval for publication. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use.
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| JOURNAL |
Modeling the Formation of Secondary Organic Aerosol Within a Comprehensive Air Quality Model System |
01/01/2001
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Schell, B., I. J. Ackermann, H. Hass, F. S. Binkowski, AND A. Ebel. Modeling the Formation of Secondary Organic Aerosol Within a Comprehensive Air Quality Model System. , 2001. JOURNAL OF GEOPHYSICAL RESEARCH 106(D22):28,275-28,293, (2001).
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The aerosol component of the CMAQ model is designed to be an efficient and economical depiction of aerosol dynamics in the atmosphere. The approach taken represents the particle size distribution as the superposition of three lognormal subdistributions, called modes. The processes of coagulation, particle growth by the addition of new mass, particle formation, etc. are included. Time stepping is done with analytical solution to the differential equations for the conservation of number and species mass. The component considers both PM2.5 and PM10 and includes estimates of the primary emissions of elemental and organic carbon, dust and other species not further specified. Secondary species considered are sulfate, nitrate, ammonium, water and organics from precursors of anthropogenic and biogenic origin. Extinction of visible light by aerosols isrepresented by two methods: a parametric approximation to Mie extinction and an empirical approach based upon field data. The algorithms that simulate cloud interactions with aerosols are also described. Results from a box model simulation and a three-dimensional simulation are exhibited.
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| JOURNAL |
Airshed Domains for Modeling Atmospheric Deposition of Oxidized and Reduced Nitrogen to the Neuse/Pamlico System of North Carolina |
11/30/2001
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Dennis, R. L. AND R. Mathur. Airshed Domains for Modeling Atmospheric Deposition of Oxidized and Reduced Nitrogen to the Neuse/Pamlico System of North Carolina. Dr. Miquel A. Medina, Dro. Zbigniew J. Kabala (ed.), HYDROLOGICAL SCIENCE AND TECHNOLOGY 17(1-4):107-117, (2001).
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Atmospheric deposition is important to nutrient loadings to coastal estuaries. Atmospheric emissions of nitrogen travel hundreds of kilometers as they are removed via atmospheric deposition. Long-range transport from outside the Neuse/Pamlico system in North Carolina is an important contributor to the total (wet + dry) deposition of nitrogen to the watershed, estuary and Sound. We need to delimit the extent of long-range transport that significantly contributes to deposition and thus loadings. Since airsheds do not have natural boundaries, in contrast to watersheds, an approach to define principal airsheds has been developed using simulations of the Extended Regional Acid Deposition Model. Principal airsheds for the deposition of oxidized nitrogen (nitrates/nitric acid), and reduced nitrogen (ammonium/ammonia) are defined and characterized. The principal airshed for oxidized nitrogen is 665,600 km2 and for reduced nitrogen it is 406,400 km2, 25 and 15 times larger than the drainage area, respectively. Nitrogen oxide emissions from within the oxidized nitrogen principal airshed are estimated to explain 63% of the oxidized nitrogen deposition to the Neuse/Pamlico system. Ammonia emissions from within the reduced nitrogen principal airshed are estimated to explain 60% of the reduced nitrogen deposition to the system for 1996 emissions. North Carolina emissions contribute a large share of the reduced nitrogen deposition, but a small share of the oxidized nitrogen deposition, estimated to be 45% and 20%, respectively. Thus, a large regional atmospheric perspective is necessary for multi-media modeling involving nutrient deposition to coastal estuaries.
This paper has been reviewed in accordance with the U.S. EPA's peer review policies and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
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| JOURNAL |
Developing Seasonal Ammonia Emission Estimates With An Inverse Modeling Technique |
11/01/2001
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Gilliland, A. B., R. L. Dennis, S. J. Roselle, T. E. Pierce Jr., AND L. E. Bender. Developing Seasonal Ammonia Emission Estimates With An Inverse Modeling Technique. THE SCIENTIFIC WORLD JOURNAL 1((S2)):356-362, (2001).
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Significant uncertainty exists in magnitude and variability of ammonia (NH3) emissions, which are needed for air quality modeling of aerosols and deposition of nitrogen compounds. Approximately 85% of NH3 emissions are estimated to come from agricultural non-point sources. We suspect a strong seasonal pattern in NH3 emissions because of the volatility of ammonia, which is temperature dependent, and the seasonality of agricultural practices. However, current NH3 emission inventories' lack of intra-annual variability that could significantly affect model predicted concentrations and wet and dry deposition of nitrogen-containing compounds. We apply a Kalman filter inverse modeling technique to deduce monthly NH3 emissions for the eastern United States. Final products of this research will include monthly emissions estimates from each season. Results for January and June 1990 are currently available and are presented here. The U.S. Environmental Protection Agency (USEPA) Community Multiscale Air Quality (CMAQ) model and ammonium (NH4+) wet concentration data from the National Atmospheric Deposition Program (NADP) network are used. The inverse modeling technique estimates the emission adjustments that provide optimal modeled results with respect to wet NH4+ concentrations, observational data error, and emission uncertainty. Our results suggest that NH3 emissions estimates should be decreased by 64% for January 1990 and increased by 25% for June 1990. These results illustrate the strong differences that are anticipated for NH3 emissions.
This paper has been subjected to U.S. Environmental Protection Agency peer review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
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| PRESENTATION |
Results of Photochemical Simulations of Subgrid Scale Point Source Emissions With the Models-3 Cmaq Modeling System |
01/14/2001
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Godowitch, J. M. Results of Photochemical Simulations of Subgrid Scale Point Source Emissions With the Models-3 Cmaq Modeling System. Presented at Millenium Symposium on Atmospheric Chemistry, Albuquerque, NM, January 14-19, 2001.
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The Community Multiscale Air Quality (CMAQ) / Plume-in-Grid (PinG) model was applied on a domain encompassing the greater Nashville, Tennessee region. Model simulations were performed for selected days in July 1995 during the Southern Oxidant Study (SOS) field study program which was conducted in the Nashville area. In particular, five major point sources exhibiting a range of Nox emission rates were selected for the PinG treatment. Selected PinG model concentrations and representative examples of the initial results of an ongoing evaluation of the PinG model with the SOS/Nashville data are presented to provide a preliminary demonstration of the capability of the CMAQ/PinG approach. In particular, modeled concentrations of ozone, SO2, and nitrogen oxides are compared to plume data collected during horizontal traverses by an instrumented helicopter and research aircraft across different plumes. Statistical results are also provided at 40 km downwind of the largest point source. The comparisons and quantitative results are encouraging as PinG exhibited the capability to realistically simulate the observed photochemical evolution for ozone and other species at various downwind distances for these cases.
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| PRESENTATION |
On the Use of Nexrad Stage Iv Data in the Multimedia Modeling of Pollutant Transport |
01/14/2001
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Eder, B. K., S. K. LeDuc, A. B. Gilliland, AND P. L. Finkelstein. On the Use of Nexrad Stage Iv Data in the Multimedia Modeling of Pollutant Transport. Presented at Symposium on Precipitation Extremes: Prediction, Impacts, and Responses, Boston, MA, January 14-19, 2001.
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The Environmental Protection Agency (EPA) is designing the Multimedia Integrated Modeling System (MIMS) to model the cycling of pollutants and nutrients between the atmosphere and the earth's surface, including water bodies and groundwater. Our ability to accurately model both atmospheric, hydrological and surface processes that transport chemicals is highly dependent on precipitation types, rates and totals. Of special interest are precipitation extremes and subsequent flooding, which can greatly enhance the movement of such chemicals. During such events, these chemicals can enter the surface water bodies via groundwater recharged as well as overland flow. For example, the extreme flooding associated with Hurricane Floyd, which made landfall in North Carolina during September of 1999, transported tremendous amounts of agricultural and industrial waste and pesticides into area estuaries and rivers. This hurricane, which made landfall shortly after an earlier hurricane, Dennis, inundated sections of eastern North Carolina with more than 20 inches of rain. During the development of MIMS, we are investigating the use of the National Weather Service NEXRAD (NEXt generation RADar) Stage IV precipitation estimates in our modeling efforts. The NEXRAD Stage IV data consists of precipitation data fields that have assimilated both rain gage data and WSR-88D (Weather Surveillance Radar 1988 Doppler Version) data into a comprehensive hourly, national data set with a 4-km2 resolution. The purpose of this research is to evaluate the quality and identify limitations of the NEXRAD data through a comparison with "ground truth" data obtained from a network of ten closely spaced rain gages. The evaluation, which will use visualization tools and statistical analyses will determine if the spatial resolution of NEXRAD data is adequate to capture the spatial variability of precipitation on the watershed that is used in the surface hydrology models associated with MIMS.
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| PRESENTATION |
Supporting the Data Needs of the Coastal Community II: Hurricane Floyd Post-Event |
01/14/2001
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LeDuc, S. K. Supporting the Data Needs of the Coastal Community II: Hurricane Floyd Post-Event. Presented at 17th Conference on Interactive Information and Processing Systems for Meteorology, Oceanography, and Hydrology, Boston, MA, January 14-19, 2001.
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The Environmental Protection Agency (EPA) is cooperating with federal, state, and local organizations in developing tools necessary to predict the effects on water quality of various events. The most dramatic of these events in recent years was the extensive damage to fragile coastal environments in the State of North Carolina as a result of Hurricane Floyd. This event and the runoff from this event had major impacts on the water quality. Pollutants on the earth's surface can be transported into surface water bodies inland and in coastal areas. Hurricane flooding, like that associated with Hurricane Floyd, can transport tremendous amounts of animal waste and pesticides from agricultural lands into a river. Pollutants can also enter the surface water bodies via groundwater recharge during such storm events. This event serves as a dramatic example of the data needs for analyzing impacts. The data acquired and presented were all available for Internet access and tools were developed to process and present data in an interpretive form. This capability is indicative of the potential use and interest EPA has in the National Coastal Data Development Center (NCDDC).
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| PRESENTATION |
Air Quality Modeling at Neighborhood Scales to Improve Human Exposure Assessment |
03/19/2001
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Ching, J. S., A. Lacser, D. W. Byun, AND W. G. Benjey. Air Quality Modeling at Neighborhood Scales to Improve Human Exposure Assessment. Presented at Third International Conference on Urban Air Quality, Loutraki, Greece, March 19-23, 2001.
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Air quality modeling is an integral component of risk assessment and of subsequent development of effective and efficient management of air quality. Urban areas introduce of fresh sources of pollutants into regional background producing significant spatial variability of the concentration fields and corresponding human exposures. Typically, air pollutant concentration data in urban areas used by exposure models are from central site monitors that provide limited or no information on spatial variability. This paper describes a methodology for bridging air quality dispersion modeling and exposure approaches to provide a basis for assessing the impacts of such concentration variation on human exposures. For this approach the Models-3 Community Multiscale Air Quality Modeling System (CMAQ) (Byun and Ching, 1999) spatial resolution was refined from 4km to 1.33km. This preliminary sensitivity study will illustrate human exposure to several pollutants as a function of these grid sizes. The approach sets the stage for the modeling of exposure to air toxics.
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| PRESENTATION |
Nonlinearities in the Sulfate Secondary Fine Particulate Response to NOx Emissions Reductions as Modeled By the Regional Acid Deposition Model |
05/14/2001
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Dennis, R. L., G. S. Tonnesen, AND R. Mathur. Nonlinearities in the Sulfate Secondary Fine Particulate Response to NOx Emissions Reductions as Modeled By the Regional Acid Deposition Model. Presented at Millennium NATO/CCMS International Technical Meeting on Air Pollution Modeling and Its Application, Boulder, CO, May 15-19, 2000.
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Attention is increasingly being devoted to the health effects of fine particulates. In regions that have a large production of sulfate, sulfuric acid and nitric acid compete for the available ammonia to form aerosols. In addition, the available nitric acid is the result of urban and regional photochemical production, as are the oxidant fields involved in the oxidation of SO2 to sulfate. To create an integrated modeling capability to investigate the particulate cycling, the Regional Acid Deposition Model (RADM) was enhanced by adding several modules to dynamically represent the physical and chemical processes involved in the geochemical cycling of sulfate and reduced and oxidized forms of nitrogen. The modules are based on those of the Regional Particulate Model (RPM); the resulting version of the model is referred to as the Extended RADM. The Extended RADM is used to investigate the connection between oxidant production and secondary particulate production resulting from NOx-SOx-NHx interactions.
The reduction of regional NOx emissions from major point sources has been proposed as a means to reduce levels of regional and urban ozone. Many thought the overall level of sulfate and nitrate fine particulate, and the associated ammonium, would decrease for these emissions reductions. The effect on secondary fine particulate levels resulting from a reduction in regional NOx emissions for the eastern United States was investigated with the Extended RADM. It was found that in parts of the domain, but not everywhere, the fine particulate mass increased due to increases in sulfate. In different parts the reason for the increase was different. Around a few cities the increase in OH associated with the NOx - Ozone disbenefit was the cause. In western Pennsylvania, the increase in hydrogen peroxide due to increased radical termination was the cause. The nonlinear increase in fine particle mass due to a reduction in NOx emissions is explainable through the examination of the response in different chemical regimes.
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| PRESENTATION |
Implementation of the Smoke Emission Data Processor and Smoke Tool Input Data Processor in Models-3 |
05/01/2001
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Benjey, W. G., M. R. Houyoux, AND J. W. Susick. Implementation of the Smoke Emission Data Processor and Smoke Tool Input Data Processor in Models-3. Presented at The Emission Inventory Conference, Denver, CO, May 1-4, 2001.
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The U.S. Environmental Protection Agency has implemented Version 1.3 of SMOKE (Sparse Matrix Object Kernel Emission) processor for preparation of area, mobile, point, and biogenic sources emission data within Version 4.1 of the Models-3 air quality modeling framework. The SMOKE system includes MOBILE 5b to model on-road emissions and the Biogenic Emission Inventory System, Version 2 (BEIS 2) to model biogenic emissions. Although SMOKE may be operated from scripts outside of the Models-3 framework, integration within the system allows automatic registration and tracking of input and output files, as well as close coupling to the Community Multiscale Air Quality (CMAQ) modeling system and visualization tools by using the Net CDF I/O API data format convention. Models-3 also includes the SMOKE Tool to assist in preparation of emission input data for SMOKE. The SMOKE Tool performs basic functions for the user, including 1) import and quality checking of emission inventory and related data, 2) preparation of user-defined model grids and gridding of emission data and surrogates (SMOKE Tool requires a Geographic Information System (GIS), 3) preparation of user-defined "packet" files which instruct SMOKE to apply factors including growth, control, and reactivity analysis factors (individual species may be added or deleted by source and location), and 4) allows the user to edit input files. Manual preparation of input files outside of the system is possible, but increases the probability of human error and substantially increases the time needed for data preparation.
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| PRESENTATION |
Development of Real-Time Site-Specific Microscale Emission Factor Model for the Assessment of Human Exposure to Motor Vehicle Emissions |
03/26/2001
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Singh, R. B., A. H. Huber, AND J. N. Braddock. Development of Real-Time Site-Specific Microscale Emission Factor Model for the Assessment of Human Exposure to Motor Vehicle Emissions. Presented at 11th Coordinating Research Council On-Road Vehicle Emissions Workshop, San Diego, CA, March 26-28, 2001.
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The United States Environmental Protection Agency's (EPA) National Expsoure Research Laboratory (NERL) has initiated a project to improve the methodology for modeling urban-scale human exposure to mobile source emissions. The modeling project has started by considering the need for an emission model that is structured to support human exposure assessment. Current emission models have not been designed to estimate real-time emissions needed to support human exposure studies near roadways. Disaggregated real-time emission factors are needed for roadway dispersion and human exposure modeling in specific microenvironments. The MicroFac models are being developed from existing databases using new modeling approaches suitable for microscale modeling. This presentation summarizes progress on the model development and example applications.
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| PRESENTATION |
Development of a Microscale Emission Factor Model for Particulate Matter (Microfacpm) for Predicting Real-Time Motor Vehicle Emissions |
06/24/2001
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Singh, R. B., A. H. Huber, AND J. N. Braddock. Development of a Microscale Emission Factor Model for Particulate Matter (Microfacpm) for Predicting Real-Time Motor Vehicle Emissions. Presented at 94th AWMA Conference, Orlando, FL, June 24-28, 2001.
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The United States Environmental Protection Agency's National Exposure Research Laboratory has initiated a project to improve the methodology for modeling human exposure to motor vehicle emissions. The overall project goal is to develop improved methods for modeling the source through the air pathway to human exposure in significant microenvironments of exposure. The PART models (used in the United States, except California) and EMFAC models (used in California only) used to estimate emissions are suitable only for regional (county) scale modeling and emission inventories because of their dependence on aggregated vehicle-miles-traveled data. These emission models are not designed to estimate real-time emissions needed for human exposure studies near roadways. Therefore, there is a need to develop site-specific real-time emission factor models for PM emissions.
A microscale emission factor model for predicting site-specific real-time motor vehicle particulate matter (MicroFacPM) emissions for TSP, PM10 and PM2.5 has been developed. It uses site-specific available information on the vehicle fleet composition. The algorithm used to calculate emission factors in MicroFacPM is disaggregated based on the site-specific vehicle fleet. The emission factors are calculated from a real-time fleet, rather than from a fleet-wide average estimated by a vehicle-miles-traveled weighting of the emission factors for different vehicle classes. MicroFacPM requires input information necessary to characterize the site-specific real-time fleet being modeled. Other variables required are average vehicle speed, time and day of the year, ambient temperature and relative humidity.
The U.S. Environmental Protection Agency through its Office of Research and Development funded the research described here. This manuscript has been subjected to Agency review and approval for publication. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use.
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| PRESENTATION |
Development and Applications of Cfd in Support of Air Quality Studies of Roadway and Building Microenvironments |
06/24/2001
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Huber, A. H., M. Freeman, S. Rida, K. H. Kuehlert, AND I. S. Bish. Development and Applications of Cfd in Support of Air Quality Studies of Roadway and Building Microenvironments. Presented at 94th AWMA Conference, Orlando, FL, June 24-28, 2001.
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There is a need to develop modeling and data analysis tools to increase our understanding of human exposures to air pollutants beyond what can be explained by "limited" field data. Modeling simulations of complex distributions of pollutant concentrations within roadway and building microenvironments is feasible using high performance computing. Output from high performance computing can both be directly used to better understand specific exposure events and used to develop better simplified model approximations that may be generally applied. Unlike most currently used regulatory air quality models, Computational Fluid Dynamics (CFD) simulations are able to account rigorously for topographical details such as terrain variations and building structures in urban areas as well as local aerodynamics and turbulence. This paper discusses the development and application of CFD simulations through case studies using Fluent, Inc. Computational Fluid Dynamics software for simulating air pollutant concentrations from sources near roadways and buildings. Comparisons of CFD simulations to both wind tunnel and field measured wind and pollutant concentrations are bing used to provide evaluation/validation examples that document the reliability and accuracy of Fluent's existing CFD software. This paper presents a report on progress.
The U.S. Environmental Protection Agency through its Office of Research and Development funded the research described here. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use.
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| PRESENTATION |
Implementation of An Urban Canopy Parameterization in Mm5 for Meso-Gamma-Scale Air Quality Modeling Applications |
07/30/2001
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Otte, T. L. AND A. Lacser. Implementation of An Urban Canopy Parameterization in Mm5 for Meso-Gamma-Scale Air Quality Modeling Applications. Presented at AMS Ninth Conference on Mesoscale Processes, Ft. Lauderdale, FL, July 30-August 2, 2001.
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The U.S. Environmental Protection Agency (U.S. EPA) is extending its Models-3/Community Multiscale Air Quality (CMAQ) Modeling System to provide detailed gridded air quality concentration fields and sub-grid variability characterization at neighborhood scales and in urban areas. CMAQ is an advanced air quality modeling system that embodies a "one-atmosphere," multiple-pollutant philosophy (Byun and Ching, 1999). There are three primary models within Models-3/CMAQ: meteorology, emissions, and chemistry. The meteorology model used with CMAQ in this application is the Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) Mesoscale Model (MM5; Grell et al. 1994). For fine-scale urban simulations (~1-km grid spacing), MM5 has been modified to include an urban canopy parameterization that accounts for drag exerted by the urban structures, the enhancement of turbulent kinetic energy (especially near the top of the buildings), and the energy budget at the street and roof levels. This refinement of MM5 is targeted to provide CMAQ with the means to capture the details of pollutant spatial distributions at these scales.
One of the goals of this research is to demonstrate the capability of MM5 to simulate the effects of urban areas at the meso-gamma scale. This paper describes the suggested modifications to MM5 and presents preliminary results of using the urban canopy parameterization.
The information in this manuscript has been funded by the United States Environmental Protection Agency. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
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| PRESENTATION |
A Preliminary Evaluation of Models-3 Cmaq Using Particulate Matter Data from the Improve Network |
10/15/2001
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Eder, B. K., M. R. Mebust, AND S. K. LeDuc. A Preliminary Evaluation of Models-3 Cmaq Using Particulate Matter Data from the Improve Network. Presented at 25th NATO/CCMS International Technical Meeting on Air Pollution Modeling and Its Application, Louvain-la-Neuve, Belgium, October 15-19, 2001.
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The Clean Air Act and its Amendments require the United States Environmental Protection Agency (EPA) to establish National Ambient Air Quality Standards for Particulate Matter (PM) and to assess current and future air quality regulations designed to protect human health and welfare. Air quality models, such as EPA's Models-3 Community Multiscale Air Quality model (CMAQ) [Byun and Ching, 1999], provide one of the most reliable tools for performing such assessments. CMAQ simulates air concentrations and deposition of various pollutants including PM. These simulations, which can be conducted on a myriad of spatial and temporal scales, support both regulatory assessment as well as scientific studies by research institutions. Within CMAQ is an aerosol component, or module, designed to simulate the complex processes involving PM, which is commonly separated into PM2.5 and PM10. In order to determine its value to the air quality regulatory communities, CMAQ needs to be evaluated using observational data. One such evaluation, which compared visibility parameters derived from CMAQ to visibility parameters obtained from National Weather Service observations, revealed that CMAQ was able to replicate general spatial and temporal patterns [Eder et al., 2000]. The current evaluation compares PM simulated by CMAQ with PM data collected by the Interagency Monitoring of PROtected Visual Environments (IMPROVE) network.
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| PRESENTATION |
Modeling Air Toxics and PM 2.5 Concentration Fields as a Means for Facilitating Human Exposure Assessments |
09/17/2001
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Ching, J. S. Modeling Air Toxics and PM 2.5 Concentration Fields as a Means for Facilitating Human Exposure Assessments. Presented at 10th International Symposium Transport and Air Pollution, Boulder, CO, September 17-19, 2001.
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The capability of the US EPA Models-3/Community Multiscale Air Quality (CMAQ) modeling system is extended to provide gridded ambient air quality concentration fields at fine scales. These fields will drive human exposure to air toxics and fine particulate matter (PM2.5) models, and ultimately influence implementation of ambient air quality regulatory standards. Sub-grid variability of the pollutant distribution serves as ancillary information for exposure assessments and "hot-spot" analyses to assess impacts of various sources of air toxic pollutants. This paper describes the modeling enhancements to the existing CMAQ, as well as the strategy we are exploring to provide the sub-grid scale details that fulfill the proposed model design requirements and functionality.
The information in this manuscript has been prepared under funding by the United States Environmental Protection Agency. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
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| PRESENTATION |
Updates and Evaluation of the Px-Lsm in Mm5 |
06/25/2001
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Pleim, J. A. AND A. Xiu. Updates and Evaluation of the Px-Lsm in Mm5. Presented at MM5 Users Workshop, Boulder, CO, June 25-27, 2001.
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Starting with Version 3.4, there is a new land surface model known as the Pleim-Xiu LSM available in the MM5 system. Pleim and Xiu (1995) described the initial development and testing of this land surface and workshop proceedings provided a basic description of the model and some evaluation (Pleim and Xiu, 2000). A recent journal article (Xiu and Pleim, 2001) presents a more detailed description of the LSM and its implementation in MM5 and further evaluation. This paper outlines some bug fixes, updates, guidance for use, and more evaluation.
This paper has been reviewed in accordance with the US Environmental Protection Agency's peer and administrative review policies and approved for presentation and publication.
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| PUBLISHED REPORT |
Models-3 Installation Procedures for a Sun Workstation With a Unix-Based Operating System (Models-3 Version 4.1) |
06/04/2001
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Atmospheric Modeling Division, AND EPA Systems Development Center. Models-3 Installation Procedures for a Sun Workstation With a Unix-Based Operating System (Models-3 Version 4.1). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-01/037 (NTIS PB2002-107934), 2001.
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Models-3 is a flexible system designed to simplify the development and use of air quality models and other environmental decision support tools. It is designed for applications ranging from regulatory and policy analysis to understanding the complex interactions of atmospheric chemistry and physics. The May 2001 release of Models-3 contains a Community Multi-scale Air Quality (CMAQ) modeling system for urban to regional scale air quality simulation of tropospheric ozone, acid deposition, visibility, and fine particles. The major improvements in CMAQ since the June 2000 release include the Modified Euler Backward Iterative (MEBI) chemical solver for use with CB4 gas-phase mechanisms, improved horizontal diffusion, and an improved aerosol module. Principal changes to other parts of the Models-3 system improvements include the replacement of the former emission modeling system with provision to use the Sparse Matrix Operator Kernel Emission (SMOKE) modeling system (available at no cost from MCNC, North Carolina Supercomputing Center), and a SMOKE Tool to create input files for SMOKE. This Installation Manual includes an overview of the system architecture, installation requirements, procedures for installation of the Models-3 server and clients, establishing users, Models-3 start-up and shut-down, loading of data sets, description of system administration functions, and illustrative examples. Release notes describing system changes (including SMOKE Tool) are in Appendices G and H.
This updated installation and operation manual is a part of the documentation set for the Models-3 Third Generation Air Quality Modeling System. The U.S. Environmental Protection Agency through its Office of Research and Development partially funded and collaborated in the procedures described here under contracts 68-W1-0055 and 68-W-99-002 to Science Applications International Corporation. This Manual has been subjected to the Agency's peer and administrative review and has been approved for publication as an EPA document. Mention of trade names or commercial products is not intended to constitute endorsement or recommendation for use.
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| PUBLISHED REPORT |
Models-3 Installation Procedures for a Personal Computer With a Nt Operating System (Models-3 Version 4.1) |
09/21/2001
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Atmospheric Modeling Division, AND EPA Systems Development Center. Models-3 Installation Procedures for a Personal Computer With a Nt Operating System (Models-3 Version 4.1). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-01/046 (NTIS PB2002-100445), 2001.
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Models-3 is a flexible system designed to simplify the development and use of air quality models and other environmental decision support tools. It is designed for applications ranging from regulatory and policy analysis to understanding the complex interactions of atmospheric chemistry and physics. The 2001 release of Models-3 contains a Community Multi-Scale Air Quality (CMAQ) modeling system for urban to regional scale air quality simulation of tropospheric ozone, acid deposition, visibility, and fine particles. The major improvements in CMAQ since the June 2000 release include the Modified Euler Backward Iterative (MEBI) chemical solver for use with CB4 gas-phase mechanisms, improved horizontal diffusion, and an improved aerosol module. Principal changes to other parts of the Models-3 system improvements include the replacement of the former emission modeling system with provision to use the Sparse Matrix Operator Kernel Emission (SMOKE) modeling system (available at no cost from MCNC, North Carolina Supercomputing Center), and SMOKE Tool to create input files for SMOKE. This Installation Manual is for both new installations and upgrades, and includes an overview of the Models-3 server and clients, establishing users, Models-3 start-up and shut-down, loading of data sets, description of system administration functions, and illustrative examples. Release notes describing changes (including SMOKE Tool) are in the Appendices.
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| PUBLISHED REPORT |
Smoke Tool for Models-3 Version 4.1 Structure and Operation Documentation |
08/02/2001
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Atmospheric Modeling Division, AND EPA Systems Development Center. Smoke Tool for Models-3 Version 4.1 Structure and Operation Documentation. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-01/048 (NTIS PB2001-108312), 2001.
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The SMOKE Tool is a part of the Models-3 system, a flexible software system designed to simplify the development and use of air quality models and other environmental decision support tools. The SMOKE Tool is an input processor for SMOKE, (Sparse Matrix Operator Kernel Emission system) the air emission modeling component of Version 4.1 of Models-3. The SMOKE Tool provides emission file in the correct format, creates gridded files of emission data, and performs quality control and analysis of emission data for SMOKE. SMOKE Tool may be operated either within the graphical user interface of Models-3 system, or independently in a "stand-alone" mode. SMOKE Tool is made available with a set of standard EPA emission inventories for the years 1990, 1995, and 1996 as well as economic projection factors and temporal and spatial allocation data. This document provides detailed descriptions of the software structure, related file formats and assumptions, environment variable settings, and other details for the use of SMOKE Tool. SMOKE Tool and this document are available from the Models-3 web site at http://www.epa.gov/asmdnerl/models3/.
This document has been subjected to the Agency's peer and administrative review and has been approved for publication as an EPA document. Mention of trade names or commercial products is not intended to constitute endorsement or recommendation for use.
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| PUBLISHED REPORT |
Release Notes for Models-3 Version 4.1 Patch: Smoke Tool and File Converter |
10/03/2001
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Atmospheric Modeling Division, AND EPA Systems Development Center. Release Notes for Models-3 Version 4.1 Patch: Smoke Tool and File Converter. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-01/076 (NTIS PB2002-101194), 2001.
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This software patch to the Models-3 system corrects minor errors in the Models-3 framework, provides substantial improvements in the ASCII to I/O API format conversion of the File Converter utility, and new functionalities for the SMOKE Tool. Version 4.1 of the Models-3 system must be installed before applying this patch. The SMOKE Tool is an emission modeling component of Models-3, a flexible system designed to simplify the development and use of air quality models and other environmental decision support tools. Models-3 is designed for applications ranging from regulatory and policy analysis to understanding the complex interactions of atmospheric chemistry and physics. This document describes corrections to the Models-3 framework system, describes the procedures used by SMOKE Tool to grid spatial surrogate data, describes how additional spatial surrogate coverages may be added, and describes a new reverse gridding capability (gridded data to county or other geographic boundary data).
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| PUBLISHED REPORT |
Computational Methods for Sensitivity and Uncertainty Analysis for Environmental and Biological Models |
12/01/2001
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Isukapalli, S. AND P. G. Georgopoulos. Computational Methods for Sensitivity and Uncertainty Analysis for Environmental and Biological Models. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-01/068 (NTIS PB2004-102518), 2001.
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This work introduces a computationally efficient alternative method for uncertainty propagation, the Stochastic Response Surface Method (SRSM). The SRSM approximates uncertainties in model outputs through a series expansion in normal random variables (polynomial chaos expansion). The unknown coefficients in series expansions are calculated using a limited number of model simulations. This method is analogous to approximation of a deterministic system by an algebraic response surface. Further improvements in the computational efficiency of the SRSM are accomplished by coupling the SRSM with ADIFOR, which facilitates automatic calculation of partial derivatives in numerical models coded in Fortran. The coupled method, SRSM-ADIFOR, uses the model outputs and their derivatives to calculate the unknown coefficients. The SRSM and the SRSM-ADIFOR are general methods, and are applicable to any model with random inputs. The SRSM has also been implemented as a black-box, web-based tool for facilitating its easy use. The SRSM and the SRSM-ADIFOR have been applied to a set of environmental and biological models. These methods directly provide sensitivity information and individual contributions of input uncertainties to output uncertainties; conventional methods require substantially larger numbers of simulations to provide such information. Thus, the SRSM and the SRSM-ADIFOR provide computationally efficient means for uncertainty and sensitivity analysis.
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