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Atmospheric Modeling Division Publications: 2008

This page lists publication titles, citations and abstracts produced by NERL's Atmospheric Modeling Division for the year 2008, organized by Publication Type. Your search has returned 46 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

		Presented/Published
BOOK CHAPTER	Evaluating the Effects of Emission Reductions on Multiple Pollutants Simultaneously	08/03/2008

LUECKEN, D. J., A. CIMORELLI, C. STAHL, AND D. Tong. Evaluating the Effects of Emission Reductions on Multiple Pollutants Simultaneously. Chapter 7, Air Pollution Modelling and its Applications XIX. Springer-Verlag, New York, NY, 623-631, (2008).
Abstract:	Modeling studies over the Philadelphia metropolitan area have examined how emission control strategies might affect several types of air pollutants simultaneously. This study supports considering effects of multiple pollutants in determining optimum pollution control strategies.

BOOK CHAPTER	Cost 728 Project Report: Urbanization of Meteorological and Air Quality Models Chapter 5 Model Urbanization Strategy: Summaries, Recommendations and Requirements	05/18/2008

Baklanov, A., J. K. CHING, C. Grimmond, AND A. Martilli. Cost 728 Project Report: Urbanization of Meteorological and Air Quality Models Chapter 5 Model Urbanization Strategy: Summaries, Recommendations and Requirements. , Chapter 5, COST 728 Project Report: Urbanization of Meteorological and Air Quality Models. The Danish Meteorological Institute , Copenhagen, Denmark, 118-127, (2008).
Abstract:	The urban canopy (UC), the layer of the atmosphere between the ground and the top of the highest buildings, is the region where people live and human activities take place. Because of this importance (e.g., human health, preservation of buildings) significant efforts have been dedicated to its investigation. Such studies shed light on the high complexity of atmospheric circulations in the UC, primarily because of the presence of obstacles (buildings) large enough to strongly modify air flow and the thermal exchanges between these surfaces and the atmosphere.

BOOK CHAPTER	Diagnostic Analysis of the Three-Dimensional Sulfur Distributions Over the Eastern United States Using the Cmaq Model and Measurements from the Icartt Field Experiment	08/03/2008

MATHUR, R., S. J. ROSELLE, G. POULIOT, AND G. SARWAR. Diagnostic Analysis of the Three-Dimensional Sulfur Distributions Over the Eastern United States Using the Cmaq Model and Measurements from the Icartt Field Experiment. , Chapter 5, Air Pollution Modeling and its Application XIX. Springer, New York, NY, 496-504, (2008).
Abstract:	Previous comparisons of air quality modeling results from various forecast models with aircraft measurements of sulfate aerosol collected during the ICARTT field experiment indicated that models that included detailed treatment of gas- and aqueous-phase atmospheric sulfate formation, tended to overestimate airborne SO₄ ^2- levels. To understand the three-dimensional distributions and fate of atmospheric SO₄ ^2- and to diagnose the possible reasons for these over-predictions, we perform detailed analysis of modeled SO₄ ^2- budgets over the eastern U.S. during the summer of 2004 using an instrumented version of the Community Multiscale Air Quality (CMAQ), namely the sulfur -tracking model. Two sets of three-dimensional model calculations are performed using different gas-phase chemical mechanisms: (1) the widely used CBM4, and (2) the SAPRC mechanism.

BOOK CHAPTER	Has the Performance of Regional-Scale Photochemical Modelling Systems Changed Over the Past Decade?	08/03/2008

Hogrefe, C., J. Ku, G. Sistla, A. GILLILAND, J. IRWIN, P. S. Porter, E. Gego, P. Kasibhatla, AND S. RAO. Has the Performance of Regional-Scale Photochemical Modelling Systems Changed Over the Past Decade? , Chapter 4, Air Pollution Modeling and Its Application XIX. Springer, New York, NY, 394-403, (2008).
Abstract:	This study analyzed summertime ozone concentrations that have been simulated by various regional-scale photochemical modelling systems over the Eastern U.S. as part of more than ten independent studies. Results indicate that there has been a reduction of root mean square errors (RMSE) and an improvement in the ability to capture ozone fluctuations stemming from synoptic-scale meteorological forcings between the earliest seasonal modelling simulations and more recent studies.

BOOK CHAPTER	The Effect of Hetrogeneous Reactions on Model Performance for Nitrous Acid	08/03/2008

SARWAR, G., R. L. DENNIS, AND B. Vogel. The Effect of Hetrogeneous Reactions on Model Performance for Nitrous Acid. , Chapter 4, Air Pollution Modeling and its Application XIX. Springer, New York, NY, 349-357, (2008).
Abstract:	Recent studies suggest that emissions, heterogeneous reactions, and surface photolysis of adsorbed nitric acid may produce additional nitrous acid in the atmosphere. The effects of these sources on nitrous acid formation are evaluated using the Community Multiscale Air Quality modeling system. Predicted nitrous acid with and without these sources are compared with observed data from northeast Philadelphia. The incorporation of these sources greatly improved the model performance for nitrous acid. It also increases the average hydroxyl radical and ozone by 10% and 1.7 ppbv, respectively.

BOOK CHAPTER	The Effect of Lateral Boundary Values on Atmospheric Mercury Simulations With the Cmaq Model	08/03/2008

BULLOCK, R. The Effect of Lateral Boundary Values on Atmospheric Mercury Simulations With the Cmaq Model. , Chapter 2, Carlos Borrego; Ana Isabel Miranda (ed.), Air Pollution Modeling and its Application XIX. Springer, New York, NY, (Series C):173-181, (2008).
Abstract:	Simulation results from three global-scale models of atmospheric mercury have been used to define three sets of initial condition and boundary condition (IC/BC) data for regional-scale model simulations over North America using the Community Multi-scale Air Quality (CMAQ) model. The IC/BC data sets derived from these models show significant differences in air concentration of mercury species. Variations in the CMAQ model simulation results obtained from each of the three IC/BC data sets provide a measure of the range of certainty regarding patterns of mercury deposition across the study region and the relative importance of domestic versus foreign emission sources responsible for these deposition patterns

BOOK CHAPTER	A Modeling Methodology to Support Evaluation Public Health Impacts on Air Pollution Reduction Programs	08/03/2008

ISAKOV, V. AND H. A. OZKAYNAK. A Modeling Methodology to Support Evaluation Public Health Impacts on Air Pollution Reduction Programs. , Chapter 7, Carlos Borrego, Ana Isabel Miranda (ed.), Air Pollution Modeling and Its Application XIX. Springer, New York, NY, 614-622, (2008).
Abstract:	Environmental public health protection requires a good understanding of types and locations of pollutant emissions of health concern and their relationship to environmental public health indicators. Therefore, it is necessary to develop the methodologies, data sources, and tools for assessing the public health impact of air pollution reduction programs, also referred to as accountability analysis.

BOOK CHAPTER	Linking Global and Regional Models to Simulate U.S. Air Quality in the Year 2050	08/03/2008

NOLTE, C. G., A. GILLILAND, AND C. Hogrefe. Linking Global and Regional Models to Simulate U.S. Air Quality in the Year 2050. , Chapter 6, Carlos Borrego, Ana Isabel Miranda (ed.), Air Pollution Modeling and Its Application XIX. Springer, New York, NY, 559-567, (2008).
Abstract:	The potential impact of global climate change on future air quality in the United States is investigated with global and regional-scale models. Regional climate model scenarios are developed by dynamically downscaling the outputs from a global chemistry and climate model and are then used by the Community Multiscale Air Quality (CMAQ) model to simulate climatological air quality.

BOOK CHAPTER	Developing a Method for Resolving NOx Emission Inventory Biases Using Discrete Kalman Filter Inversion, Direct Sensitivities, and Satellite-Based Columns	08/03/2008

NAPELENOK, S., R. W. PINDER, A. GILLILAND, AND R. V. Marin. Developing a Method for Resolving NOx Emission Inventory Biases Using Discrete Kalman Filter Inversion, Direct Sensitivities, and Satellite-Based Columns. , Chapter 3, Carlos Borrego, Ana Isabel Miranda (ed.), Air Pollution Modeling and its Application XIX. Springer, New York, NY, 322-330, (2008).
Abstract:	An inverse method was developed to integrate satellite observations of atmospheric pollutant column concentrations and direct sensitivities predicted by a regional air quality model in order to discern biases in the emissions of the pollutant precursors.

BOOK CHAPTER	Evaluating Regional-Scale Air Quality Models	08/03/2008

GILLILAND, A., J. M. GODOWITCH, C. Hogrefe, AND S. RAO. Evaluating Regional-Scale Air Quality Models. , Chapter 4, Carlos Borrego, Ana Isabel Miranda (ed.), Air Pollution Modeling and Its Application XIX. Springer, New York, NY, 412-419, (2008).
Abstract:	Numerical air quality models are being used to understand the complex interplay among emission loading meteorology, and atmospheric chemistry leading to the formation and accumulation of pollutants in the atmosphere. A model evaluation framework is presented here that considers several types of approaches, referred to here as the operational evaluation, diagnostic evaluation, dynamic evaluation, and probabilistic evaluation.

BOOK CHAPTER	Toward a US National Air Quality Forecast Capability: Current and Planned Capabilities	08/03/2008

Davidson, P., K. L. SCHERE, R. Draxter, S. Kondragunta, R. WAYLAND, J. F. Meagher, AND R. MATHUR. Toward a US National Air Quality Forecast Capability: Current and Planned Capabilities. , Chapter 2, Carlos Borrego, Ana Isabel Miranda (ed.), Air Pollution Modeling and its Application XIX. Springer, New York, NY, 226-234, (2008).
Abstract:	As mandated by Congress, NOAA is establishing a US national air quality forecast capability. This capability is being built with EPA, to provide air quality forecast information with enough accuracy and lead-time so that people can take actions to limit harmful effects of poor air quality.

BOOK CHAPTER	Development of Fire Emissions Inventory Using Satellite Data	08/03/2008

ROY, D., G. POULIOT, D. MOBLEY, G. Thompson, T. E. PIERCE, A. J. SOJA, J. J. SZYKMAN, AND J. Al-Saadi. Development of Fire Emissions Inventory Using Satellite Data. , Chapter 2, Carlos Borrego, Ana Isabel Miranda (ed.), Air Pollution Modeling and its Application XIX. Springer, New York, NY, 217-225, (2008).
Abstract:	There are multiple satellites observing and reporting fire imagery at various spatial and temporal resolutions and each system has inherent merits and deficiencies. In our study, data are acquired from the Moderate Resolution Imaging Spectro-radiometer (MODIS) aboard the National Aeronautics & Space Administration’s (NASA’s) Earth Observing System satellites. The MODIS-equipped satellite is polar orbiting with one daytime equatorial crossing and a 1-km2 resolution product. Fire-counts are obtained from two MODIS instruments aboard two different satellites having 10:30AM and 1:30PM equatorial crossing time, respectively. A general methodology of processing the MODIS data is provided. An effective area burned estimate is obtained independently from a 2002 ground-based fire database. Successful development and application of this technique for characterizing fire emissions in the United States (U.S.) could enhance the development of European techniques for characterization of fire emissions for air quality modeling and its applications.

BOOK CHAPTER	Fusing Observations and Model Results for Creation of Enhanced Ozone Spatial Fields: Comparison of Three Techniques	08/03/2008

Gego, E., P. S. Porter, V. GARCIA, C. Hogrefe, AND S. RAO. Fusing Observations and Model Results for Creation of Enhanced Ozone Spatial Fields: Comparison of Three Techniques. , Chapter 3.0, Carlos Borrego and Ana Isabel Miranda (ed.), Air Pollution Modeling and Its Application XIX. Springer, New York, NY, (Series C):339-346, (2008).
Abstract:	This paper presents three simple techniques for fusing observations and numerical model predictions. The techniques rely on model/observation bias being considered either as error free, or containing some uncertainty, the latter mitigated with a Kalman filter approach or a spatial smoothing method. The fusion techniques are applied to the daily maximum 8-hour average ozone concentrations observed in the New York state area during summer of 2001. Classical evaluation metrics (mean absolute bias, mean squared error, correlation, etc.) show that fused predictions are not better than a simple interpolation of observations. However, fused maps better reproduce the spatial texture of the model predictions.

JOURNAL	Impact of An Updated Carbon Bond Mechanism on Predictions from the Cmaq Modeling System: Preliminary Assessment	01/21/2008

SARWAR, G., D. J. LUECKEN, G. YARWOOD, G. D. WHITTEN, AND W. P. CARTER. Impact of An Updated Carbon Bond Mechanism on Predictions from the Cmaq Modeling System: Preliminary Assessment. JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY. American Meteorological Society, Boston, MA, 47(1):3-14, (2008).
Abstract:	An updated and expanded Carbon Bond mechanism (CB05) has been incorporated into the Community Multiscale Air Quality modeling system to more accurately simulate wintertime, pristine, and high altitude situations. The CB05 mechanism has nearly twice the number of reactions compared to the previous Carbon Bond IV (CB-IV) mechanism. While the expansions do provide more detailed treatment of urban areas, most of the new reactions involve biogenics, toxics, and species potentially important to particulate formation and acid deposition. Model simulations were performed using the CB05 and the CB-IV mechanisms for the winter and summer of 2001. For winter with the CB05 mechanism, ozone, aerosol nitrate, and aerosol sulfate concentrations were within 1% of the results obtained with the CB-IV mechanism. Organic carbon concentrations were within 2% of the results obtained with the CB-IV mechanism. However, formaldehyde and hydrogen peroxide concentrations were lower by 25% and 32%, respectively, during winter with the CB05 mechanism. For the summer, ozone concentrations increased by 8% with the CB05 mechanism compared to the CB-IV mechanism. The aerosol sulfate, aerosol nitrate, and organic carbon concentrations with the CB05 mechanism decreased by 8%, 2%, and 10%, respectively. The formaldehyde and hydrogen peroxide concentrations with the CB05 mechanism were lower by 12% and 47%, respectively, during summer. Model performance with the CB05 mechanism improved at high altitude conditions and in rural areas for ozone. Model performance also improved for organic carbon with the CB05 mechanism.

JOURNAL	CO-Dependencies of Reactive Air Toxic and Criteria Pollutants on Emission Reductions	05/01/2008

LUECKEN, D. J. AND A. CIMORELLI. CO-Dependencies of Reactive Air Toxic and Criteria Pollutants on Emission Reductions. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION. Air & Waste Management Association, Pittsburgh, PA, 58(5):693-701, (2008).
Abstract:	It is important to understand the effect of emission controls on the concentrations of ozone, PM_2.5, and hazardous air pollutants simultaneously, in order to evaluate the full range of both health related and economic effects. Until recently, the capability of simultaneously evaluating interrelated atmospheric pollutants ("one atmosphere" analysis) was unavailable to air quality managers. In this work, we use the Community Multi-Scale Air Quality (CMAQ) modeling system to examine the potential effect of several control strategies on concentrations of ozone, PM_2.5, and four important hazardous air pollutants: formaldehyde, acetaldehyde, acrolein and benzene. We examine the effects of these control scenarios over a domain centered on the metropolitan Philadelphia area, for 12-day episodes in July and January 2001. While NOx controls alone are generally a benefit for ozone and PM_2.5 concentrations, they are predicted to have only a small effect on formaldehyde, slightly increase acetaldehyde and acrolein concentrations, and have no effect on benzene in the summer episode. Concentrations of all pollutants except benzene in this simulation increase slightly with NOx controls in the winter episode. VOC controls alone are found to have a small effect on ozone and PM_2.5, a less than linear effect on decreasing the aldehydes, and an approximately linear effect on acrolein and benzene in summer, but a slightly larger than linear effect on aldehydes and acrolein in winter. Chemistry effects in upper layers of the model sometimes affect the surface-level concentrations. The response to both VOC and NOx controls is largely a combination of response to each separately. These simulations indicate the difficulty in assessing how toxic air pollutants might or might not respond to emission reductions aimed at decreasing criteria pollutants such as ozone and PM_2.5.

JOURNAL	Technical Challenges Involved in Implementation of VOC Reactivity-Based Control of Ozone	03/01/2008

LUECKEN, D. J. AND M. R. MEBUST. Technical Challenges Involved in Implementation of VOC Reactivity-Based Control of Ozone. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 42(5):1615-1622, (2008).
Abstract:	The control of VOC emissions based on their individual contribution to ozone formation has been the subject of intensive discussion and research in the past five years, and has gained a large degree of acceptance in the air pollution regulatory community for certain industrial operations. Despite its popularity and potential to decrease ozone formation, there are still some technical challenges that remain before we are confident that we are applying the concept of reactivity in the most beneficial manner. We examine the science behind the use of reactivity, and the Maximum Incremental Reactivity in particular, and detail where major uncertainties exist. Using box model and 3-dimensional Air Quality Models, we show that there are ways to describe a chemical's reactivity which are relatively robust across a large geographic area, and that the choice of metric used is important in determining the potential benefits and disbenefits of a reactivity-based emission control policy.

JOURNAL	Observable Indicators of the Sensitivity of PM2.5 Nitrate to Emission Reductions Part I: Derivation of the Adjusted Gas Ratio and Applicability at Regulatory-Relevant Time Scales	02/01/2008

PINDER, R. W., R. L. DENNIS, AND P. BHAVE. Observable Indicators of the Sensitivity of PM2.5 Nitrate to Emission Reductions Part I: Derivation of the Adjusted Gas Ratio and Applicability at Regulatory-Relevant Time Scales. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 42(6):1275-1286, (2008).
Abstract:	Chemical transport models have frequently been used to evaluate the impacts of emission reductions on inorganic PM2.5. However, such models are limited in their accuracy by uncertain estimates of the spatial and temporal characterization of emissions and meteorology. Site-specific observations can more accurately characterize the distribution of pollutants, but can not predict the effectiveness of emission controls. In this research, we use equilibrium theory and a chemical transport model to find observable indicators that are robust predictors of the change in PM2.5 nitrate due to changes in NH3, SO2, and NOx emissions. This permits a novel method for estimating the effectiveness of emission control strategies. The chemical transport model can be used to derive the relationship between the observed concentrations and the change in nitrate due to emission changes. Then observations can be used to apply that relationship to specific locations of interest.

JOURNAL	Modeling Urban and Regional Aerosols Application of the Cmaq Ucd Aerosol Model to Tampa, a Coastal Urban Site	04/01/2008

NOLTE, C. G., P. BHAVE, J. ARNOLD, R. L. DENNIS, M. Zhang, AND A. S. WEXLER. Modeling Urban and Regional Aerosols Application of the Cmaq Ucd Aerosol Model to Tampa, a Coastal Urban Site. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 42(13):3179-3191, (2008).
Abstract:	The UCD sectional aerosol model has been coupled to the CMAQ air quality model and used to simulate air quality in Tampa, Florida. Sea salt emissions are parameterized as a function of modeled wind speed and relative humidity. Modeled aerosol sulfate, nitrate, ammonium, sodium, and chloride concentrations are compared with measurements conducted during May 2002. Aerosol size distributions are simulated very accurately, though nitrate concentrations are underpredicted by a factor of two. The model’s depletion of chloride in coarse particles due to displacement by nitric acid is also evaluated.

JOURNAL	Linking Global to Regional Models to Assess Future Climate Impacts on Surface Ozone Concentrations in the United States	07/22/2008

NOLTE, C. G., A. GILLILAND, C. Hogrefe, AND L. J. MICKLEY. Linking Global to Regional Models to Assess Future Climate Impacts on Surface Ozone Concentrations in the United States. JOURNAL OF GEOPHYSICAL RESEARCH. American Geophysical Union, Washington, DC, 113(D14307):1-14, (2008).
Abstract:	The UCD sectional aerosol model has been coupled to the CMAQ air quality model and used to simulate air quality in Tampa, Florida. Sea salt emissions are parameterized as a function of modeled wind speed and relative humidity. Modeled aerosol sulfate, nitrate, ammonium, sodium, and chloride concentrations are compared with measurements conducted during May 2002. Aerosol size distributions are simulated very accurately, though nitrate concentrations are underpredicted by a factor of two. The model’s depletion of chloride in coarse particles due to displacement by nitric acid is also evaluated.

JOURNAL	Assessment of the Winter-Time Performance of Developmental Particulate Matter Forecasts With the Eta-Cmaq Modeling System	01/17/2008

MATHUR, R., S. YU, D. KANG, AND K. L. SCHERE. Assessment of the Winter-Time Performance of Developmental Particulate Matter Forecasts With the Eta-Cmaq Modeling System. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES. American Geophysical Union, Washington, DC, 113(D02303):1-15, (2008).
Abstract:	It is desirable for local air quality agencies to accurately forecast tropospheric PM_2.5 concentrations to alert the sensitive population of the onset, severity and duration of unhealthy air, and to encourage the public and industry to reduce emissions-producing activities. Since elevated particulate matter concentrations are encountered throughout the year, the accurate forecast of the day-to-day variability in PM_2.5 and constituent concentrations over annual cycles, poses considerable challenges. In efforts to characterize forecast model performance during different seasons, PM_2.5forecast simulations with the Eta-CMAQ system are compared with measurements from a variety of regional surface networks, with special emphasis on performance during the winter period. The analysis suggests that while the model can capture the average spatial trends and dynamic range in PM_2.5 and constituent concentrations measured at individual sites, significant variability occurs on a day-to-day basis both in the measurements and the model predictions, which are generally not well correlated when paired both in space and time. Systematic over-predictions in regional PM_2.5 forecasts during the cool season are noted through comparisons with measurements from different networks. The over-predictions are typically more pronounced at urban locations, with larger errors at the higher concentration range. Variability in aerosol sulfate concentrations were captured well as well as the relative amounts of S(IV) and S(VI). The mix of carbon sources as represented by the ratio of organic to elemental carbon is captured well in the southeastern U.S., but the total carbonaceous aerosol mass is underestimated. On average, during the winter-time, the largest over-predictions among individual PM_2.5 constituents were noted for the "other" category which predominantly represents primary emitted trace elements in the current model configuration. The systematic errors in model predictions of both total PM_2.5 and its constituents during the winter period are found to arise from a combination of uncertainties in the magnitude and spatial and temporal allocation of primary PM_2.5 emissions, current uncertainties in the estimation of chemical production pathways for secondary constituents (e.g., NO₃^-), and representation of the impacts of boundary layer mixing on simulated concentrations, especially during night-time conditions.

JOURNAL	Fate and Transport of Emissions for Several Trace Metals Over the United States	06/25/2008

HUTZELL, W. T. AND D. J. LUECKEN. Fate and Transport of Emissions for Several Trace Metals Over the United States. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier Science Ltd, New York, NY, 396(2-3):164-179, (2008).
Abstract:	A regional model for atmospheric photochemistry and particulate matter is used to predict the fate and transport of five trace metals: lead, manganese, total chromium, nickel, and cadmium over the continental United States during January and July 2001. Predicted concentrations of the metals are compared to observations. Lead predictions have the lowest mean differences with observations and the highest correlation coefficients. They best agree with observations made in January over residential and commercial areas in the eastern United States and worst with observations over remote forests and deserts located in the western United States during July. Manganese predictions show similar abilities to reproduce observations but had larger changes between months. Chromium and nickel predictions show diminishing ability to reproduce observations over both urban and rural areas. Cadmium predictions show the least ability to reproduce observations. Potential causes are examined for the errors in predictions. For errors in lead, manganese and perhaps chromium predictions, aerial suspension and biomass burning are suspected because simulations did not include emissions from these sources. Nickel, cadmium and, to a lower extent, chromium predictions suffer from errors in the emissions that represent current anthropogenic activities. Predicted concentrations of all metals show errors from not including sub-grid processes in meteorological and emission rates. Examples include sea breeze circulation along coastal areas and individual sources in urban areas. These errors reduce the ability to reproduce the time dependence of observations.

JOURNAL	Evaluation of the Community Multiscale Air Quality (Cmaq) Model Version 4.5: Uncertainties and Sensitivities Impacting Model Performance: Part II Particulate Matter	08/01/2008

APPEL, W., P. BHAVE, A. GILLILAND, G. SARWAR, AND S. J. ROSELLE. Evaluation of the Community Multiscale Air Quality (Cmaq) Model Version 4.5: Uncertainties and Sensitivities Impacting Model Performance: Part II Particulate Matter. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 42(24):6057-6066, (2008).
Abstract:	This paper presents an analysis of the CMAQ v4.5 model performance for particulate matter and its chemical components for the simulated year 2001. This is part two is two part series of papers that examines the model performance of CMAQ v4.5.

JOURNAL	Observable Indicators of the Sensitivity of PM _2.5 Nitrate to Emission Reductions, Part II: Sensitivity to Errors in Total Ammonia and Total Nitrate of the Cmaq-Predicted Nonlinear Effect of So ₂ Emission Reductions	02/01/2008

DENNIS, R. L., P. BHAVE, AND R. W. PINDER. Observable Indicators of the Sensitivity of PM _2.5 Nitrate to Emission Reductions, Part II: Sensitivity to Errors in Total Ammonia and Total Nitrate of the Cmaq-Predicted Nonlinear Effect of So ₂ Emission Reductions. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 42(6):1287-1300, (2008).
Abstract:	The inorganic aerosol system of sulfate, nitrate, and ammonium can respond nonlinearly to changes in precursor sulfur dioxide (SO₂) emissions. The potential increase in nitrate, when sulfate is reduced and the associated ammonia is released, can negate the sulfate mass reduction. Current regional-scale air quality models do not reproduce the present-day levels of total ammonia and total nitrate, leading to possible errors in the air quality model predictions of future nitrate concentrations. The objective of this study is to quantify the effects of errors in the total-ammonia and total-nitrate budgets on nitrate relative response (RR), defined as the percent change in particulate nitrate stemming from reductions in SO₂ emissions. This objective is addressed through three sensitivity studies using the Community Multiscale Air Quality model (CMAQ). These studies assess the sensitivity of the nitrate RR(%) to (1) errors in ammonia emissions, (2) errors in the heterogeneous production of nitrate from N₂O₅, and (3) errors in the NO_X emissions. The results indicate that nitrate RRs due to SO₂ emission reductions are much more sensitive to errors in the total-ammonia budget than to errors in the total-nitrate budget. The sensitivity of the nitrate RR to NO_X emissions is only moderate and is due primarily to the effect of NO_X changes on sulfate production, rather than on total nitrate. Also, a strong relationship was found between the nitrate RR and the Adjusted Gas Ratio (free ammonia adjusted for the degree of sulfate neutralization divided by total nitrate).

JOURNAL	Intercomparison of Sciamachy and Omi Tropospheric No₂ Columns: Observing the Diurnal Evolution of Chemistry and Emissions from Space	05/20/2008

BOERSMA, K., D. J. JACOB, H. J. ESKES, R. W. PINDER, J. WANG, AND R. J. VAN DER A. Intercomparison of Sciamachy and Omi Tropospheric No₂ Columns: Observing the Diurnal Evolution of Chemistry and Emissions from Space. JOURNAL OF GEOPHYSICAL RESEARCH. American Geophysical Union, Washington, DC, 113(D16S26):1-14, (2008).
Abstract:	Concurrent (August 2006) satellite measurements of tropospheric NO₂ columns from OMI aboard Aura (13:30 local overpass time) and SCIAMACHY aboard Envisat (10:00 overpass) offer an opportunity to examine the consistency between the two instruments under tropospheric background conditions and the effect of different observing times. For scenes with tropospheric NO₂ columns <5.0×10¹⁵ molec.cm^-2, SCIAMACHY and OMI agree within 1.0–2.0×10¹⁵ molec.cm^-2, consistent with the detection limits of both instruments. We find evidence for a low bias of 0.2×10 ¹⁵ molec.cm^-2 in OMI observations over remote oceans. Over the fossil fuel source regions at northern mid-latitudes, we find that SCIAMACHY observes up to 40% higher NO₂at 10:00 local time than OMI at 13:30. Over biomass burning regions in the tropics, SCIAMACHY observes up to 40% lower NO₂ columns than OMI. These differences are present in the spectral fitting of the data (slant column), and are augmented in the fossil fuel regions, and dampened in the tropical biomass burning regions by the expected increase in air mass factor as the mixing depth rises from 10:00 to 13:30. Using a global 3-D chemical transport model (GEOSChem), we show that the 10:00–13:30 decrease in tropospheric NO₂column over fossil fuel source regions can be explained by photochemical loss, dampened by the diurnal cycle of anthropogenic emissions that has a broad daytime maximum. The observed 10:00–13:30 NO₂ column increase over tropical biomass burning regions points to a sharp midday peak in emissions, and is consistent with a diurnal cycle of emissions derived from geostationary satellite fire counts.

JOURNAL	Dynamic Evaluation of Regional Air Quality Models: Assessing Changes to O ₃ Stemming from Changes in Emissions and Meteorology	06/01/2008

GILLILAND, A., C. Hogrefe, R. W. PINDER, J. M. GODOWITCH, K. FOLEY, AND S. RAO. Dynamic Evaluation of Regional Air Quality Models: Assessing Changes to O ₃ Stemming from Changes in Emissions and Meteorology. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 42(20):5110-5123, (2007).
Abstract:	Regional-scale air quality models are used to estimate the response of air pollutants to potential emission control strategies as part of the decision-making process. Traditionally, the model predicted pollutant concentrations are evaluated for the “base case” to assess a model’s ability to reproduce past observations. Dynamic evaluation approaches, which evaluate a model’s ability to accurately simulate air quality changes from given changes in emissions, are critically important to regulatory applications. Here, we investigate approaches to evaluate the Community Multiscale Air Quality (CMAQ) model’s predicted ozone (O₃) response to large NO_x emission reductions associated with the NOx State Implementation Plan (SIP) Call and on road mobile emissions. This case has the advantages that emission changes associated with the NO_x SIP Call can be well characterized and substantial changes are observed in O₃ levels. To consider the modeled response to emission changes in light of the strong meteorological influences on O₃, two time periods after the NO_x SIP Call are included with very different meteorological conditions. The sensitivity to chemical mechanisms is also considered by including simulations with the CB4, SAPRC, and CB05 chemical mechanisms. The evaluation results suggest that the air quality model predictions underestimate the O₃ reductions observed after the NO_x SIP Call was implemented. While the emission estimate uncertainties may also be a factor, the results suggest that the contribution of long-range transport of O₃ and precursors is underpredicted, especially when using the CB4 chemical mechanism. Further investigation of the chemical mechanisms’ ability to characterize tropospheric chemistry aloft is recommended. Results based on the most recent CMAQ version 4.6 with CB05 and updated emission inventories show incremental improvements to the modeled O₃ response to NO_x emission reductions.

JOURNAL	Collection of Ambient Particulate Matter By Porous Vegetation Barriers: Sampling and Characterization Methods	01/01/2008

Tiwary, A., A. H. REFF, AND J. J. COLLS. Collection of Ambient Particulate Matter By Porous Vegetation Barriers: Sampling and Characterization Methods. JOURNAL OF AEROSOL SCIENCE. Elsevier Science Ltd, New York, NY, 39(1):40-47, (2008).
Abstract:	This manuscript describes work done by A. Reff as part of a collaboration begun 3 years ago at Rutgers University with A. Tiwary who was then at the University of Nottingham. The work describes sampling and characterization methods for investigating the effects of vegetative barriers on ambient particulate matter concentrations. A small set of results are presented, an evaluation of the methodology is made, and suggestions are made for future investigations into the same phenomena.

JOURNAL	Streamwater Acid-Based Chemistry and Critical Loads of Atmospheric Sulfur Deposition in Shenandoah National Park, Virginia	02/01/2008

SULLIVAN, T. J., B. COSBY, J. R. WEBB, R. L. DENNIS, A. J. BULGER, AND F. A. DEVINEY, JR. Streamwater Acid-Based Chemistry and Critical Loads of Atmospheric Sulfur Deposition in Shenandoah National Park, Virginia. ENVIRONMENTAL MONITORING AND ASSESSMENT. Springer, New York, NY, 137(1-3):85-99, (2008).
Abstract:	A modeling study was conducted to evaluate the acid-base chemistry of streams within Shenandoah National Park, Virginia and to project future responses to sulfur (S) and nitrogen (N) atmospheric emissions controls. Many of the major stream systems in the Park have acid neutralizing capacity (ANC) less than 20 µeq/L, levels at which chronic and/or episodic adverse impacts on native brook trout are possible. Model hindcasts suggested that none of these streams had ANC less than 50 µeq/L in 1900. Model projections, based on atmospheric emissions controls representative of laws already enacted as of 2003, suggested that the ANC of those streams simulated to have experienced the largest historical decreases in ANC will increase in the future. The levels of S deposition that were simulated to cause streamwater ANC to increase or decrease to three specified critical levels (0, 20 and 50 µeq/L) ranged from less than zero (ANC level not attainable) to several hundred kg/ha/year, depending on the selected site and its inherent acid-sensitivity, selected ANC endpoint criterion, and evaluation year for which the critical load was calculated. Several of the modeled streams situated on siliciclastic geology exhibited <0 kg/ha/year to achieve ANC >50 µeq/L in the year 2040, probably due at least in part to base cation losses from watershed soil. The median modeled siliciclastic stream had a calculated critical load to achieve ANC >50 µeq/L in 2100 that was about 3 kg/ha/year, or 77% lower than deposition in 1990, representing the time of model calibration.

JOURNAL	Scientific Uncertainties in Atmospheric Mercury Models III: Boundary and Initial Conditions, Model Grid Resolution, and Hg(ii) Reduction Mechanisms	03/01/2008

PONGPRUEKSA, P., C. LIN, S. LINDBERG, C. JANG, T. BRAVERMAN, R. BULLOCK, T. C. HO, AND H. CHU. Scientific Uncertainties in Atmospheric Mercury Models III: Boundary and Initial Conditions, Model Grid Resolution, and Hg(ii) Reduction Mechanisms. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 42(8):1828-1845, (2008).
Abstract:	In this study we investigate the CMAQ model response in terms of simulated mercury concentration and deposition to boundary/initial conditions (BC/IC), model grid resolution (12- versus 36-km), and two alternative Hg(II) reduction mechanisms. The model response to the change of gaseous elemental mercury (GEM) concentration from 0 to 2 ng m^-3 in IC/BC is found to be very linear (r2 > 0.99) based on the results of sensitivity simulations in July 2001. An increase of 1 ng m^-3 of GEM in BC resulted in an increase of 0.81 ng m^-3 in the monthly average of total mercury concentration, and 1270 ng m^-2 in the monthly total deposition. IC has similar but much weaker effects compared to those of BC. Varying reactive gaseous mercury (RGM) or particulate mercury (PHg) in BC/IC has a less significant impact than for GEM. Simulation results at different grid resolutions show good agreement (slope = 0.950-1.026, r = 0.816-0.973) in mercury concentration, dry deposition, and total deposition. The agreement in wet deposition is somewhat weaker (slope = 0.770-0.794, r = 0.685-0.892). Replacing the aqueous Hg(II)-HO₂ reduction by either RGM reduction by CO (5 x 10^-18 cm³ molecule s^-1) or photoreduction of RGM (1 x 10^-5 s^-1) gives significantly better model agreement with MDN-measured deposition. Possible ranges of the reduction rates are estimated based on model sensitivity results. The kinetic estimate requires further verification by laboratory studies.

JOURNAL	Oligomers Formed Through in-Cloud Metylglyoxal Reactions: Chemical Composition, Properties, and Mechanisms Investigated By Ultra-High Resolution Ft-Icr Mass Spectrometry	03/01/2008

Altieri, K. E., S. SEITZINGER, A. M. CARLTON, B. TURPIN, G. C. Klein, AND A. G. Marshall. Oligomers Formed Through in-Cloud Metylglyoxal Reactions: Chemical Composition, Properties, and Mechanisms Investigated By Ultra-High Resolution Ft-Icr Mass Spectrometry. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 42(7):1476-1490, (2008).
Abstract:	Secondary organic aerosol (SOA) is a substantial component of total atmospheric organic particulate matter, but little is known about the composition of SOA formed through cloud processing. We conducted aqueous phase photooxidation experiments of methylglyoxal and hydroxyl radical to simulate cloud processing. Oligomer formation from methylglyoxal-hydroxyl radical reactions was detected by electrospray ionization mass spectrometry (ESI-MS). The chemical composition of the oligomers and the mechanism of their formation were investigated by ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and LCQ DUO ion trap mass spectrometry (ESI-MS-MS). Reaction products included 415 compounds detected in the mass range 245-800 Da and the elemental composition of all 415 compounds were determined by ultra-high resolution FT-ICR MS. The ratio of total organic molecular weight per organic carbon weight (OM:OC) of the oligomers (1.0-2.5) was lower than the OM:OC of the organic acid monomers (2.3-3.8) formed, suggesting that the oligomers are less hygroscopic than the organic acid monomers formed from methylglyoxal-hydroxyl radical reaction. The OM:OC of the oligomers is consistent with that of aged atmospheric aerosols and atmospheric humic like substances (HULIS). A mechanism is proposed in which the organic acid monomers formed through hydroxyl radical reactions oligomerize through esterification. The mechanism is supported by the existence of series of oligomers identified by elemental composition from FT-ICR MS and ion fragmentation patterns from ESI-MS-MS. Each oligomer series starts with an organic acid monomer formed from hydroxyl radical oxidation, and increases in molecular weight and total oxygen content through esterification with a hydroxy acid (C₃H₆O₃) resulting in multiple additions of 72.02113 Da (C₃H₄O₂ )to the parent organic acid monomer. Methylglyoxal is a water soluble product of both gas phase biogenic (i.e., isoprene) and anthropogenic (i.e., aromatics, alkenes) hydrocarbon oxidation. The varied and multiple sources of methylglyoxal increase the potential for these low volatility cloud processing products (e.g., oxalic acid and oligomers) to significantly contribute to (SOA). Aqueous phase oligomer formation investigated here and aerosol phase oligomer formation appear to be more similar than previously realized, which may simplify the incorporation of oligomers into atmospheric SOA models.

JOURNAL	Parameterization of N₂o₅ Reaction Probabilities on the Surface of Particles Containing Ammonium, Sulfate, and Nitrate	09/05/2008

Davis, J. M., P. BHAVE, AND K. FOLEY. Parameterization of N₂o₅ Reaction Probabilities on the Surface of Particles Containing Ammonium, Sulfate, and Nitrate. JOURNAL OF ATMOSPHERIC CHEMISTRY. Springer, New York, NY, 8(17):5295-5311, (2008).
Abstract:	A comprehensive parameterization was developed for the heterogeneous reaction probability (γ) of N₂O₅ as a function of temperature, relative humidity, particle composition, and phase state, for use in advanced air quality models. The reaction probabilities on aqueous NH₄HSO₄, (NH₄)₂SO₄, and NH₄NO₃ were modeled statistically using data and uncertainty values compiled from seven different laboratory studies. A separate regression model was fit to laboratory data for dry NH₄HSO₄and (NH₄)₂SO₄ particles, yielding lower γ values than the corresponding aqueous parameterizations. The regression equations reproduced 79% of the laboratory data within a factor of two and 53% within a factor of 1.25. A fixed value was selected for γ on ice-containing particles based on a review of the literature. The combined parameterization was applied under atmospheric conditions representative of the eastern United States using 3-dimensional fields of temperature, relative humidity, sulfate, nitrate, and ammonium, obtained from a recent Community Multiscale Air Quality model simulation. The resulting spatial distributions of γ were contrasted with three other parameterizations that have been applied in air quality models in the past and with atmospheric observational determinations of γ. Our results highlight a critical need for more laboratory measurements of γ at low temperature and high relative humidity, to improve model simulations of N₂O₅ hydrolysis during wintertime conditions.

JOURNAL	Resolving Local-Scale Emissions for Modeling Air Quality Near Roadways	03/01/2008

COOK, R., V. ISAKOV, J. TOUMA, W. G. BENJEY, J. THURMAN, E. KINNEE, AND D. ENSLEY. Resolving Local-Scale Emissions for Modeling Air Quality Near Roadways. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION. Air & Waste Management Association, Pittsburgh, PA, 58(3):451-461, (2007).
Abstract:	A large body of literature published in recent years suggests increased health risk due to exposure of people to air pollution in close proximity to roadways. As a result, there is a need to more accurately represent the spatial concentration gradients near roadways in order to develop mitigation strategies. In this paper, we present a practical, readily adaptable methodology, employing a “bottom up” approach to develop a detailed highway vehicle emission inventory that includes emissions for individual road links. This methodology also takes advantage of geographic information system (GIS) software to improve spatial accuracy of the activity information obtained from a Travel Demand Model. In addition we present an air quality modeling application of this methodology in New Haven, CT. This application employs a hybrid modeling approach, where a regional grid-based model is used to characterize average local ambient concentrations, and a Gaussian dispersion model is used to provide texture with the modeling domain due to spatial gradients associated with highway vehicle emissions and other local sources. Modeling results show substantial heterogeneity of pollutant concentrations within the modeling domain and strong spatial gradients associated with roadways, particularly for pollutants dominated by direct emissions.

JOURNAL	Development of a Biomass Burning Emissions By Combining Satellite and Ground-Based Information	05/16/2008

POULIOT, G., T. PACE, D. ROY, T. E. PIERCE, AND D. MOBLEY. Development of a Biomass Burning Emissions By Combining Satellite and Ground-Based Information. Journal of Applied Remote Sensing. SPIE/International Society for Optical Engineering, Bellingham, WA, 2(1):021501, (2008).
Abstract:	A 2005 biomass burning (wildfire, prescribed, and agricultural) emission inventory has been developed for the contiguous United States using a newly developed simplified method of combining information from multiple sources for use in the US EPA’s national Emission Inventory (NEI). Our method blends the temporal and spatial resolution of the remote sensing with the ground based fire size estimate. This method is faster and considerably less expensive than the method used for the 2002 National Emission Inventory and is more accurate than methods used for 2001 ant prior years. In addition, the 2004 fire inventory is the first EPA inventory utilizing remote sensing information. A comparison with the 2002 inventory for wildfire, prescribed, and agricultural fires indicates a large year-to-year variability in wildfire emissions and less variation for prescribed and agricultural fires. Total PM_2.5 emissions from wildfires, prescribed burning, and agricultural burning for the contiguous United States were estimated to be 109,000 short tons, 209,000 short tone, and 232,000 short tons, respectively, for 2005. Our total emission estimate for 2005 is 550,000 short tons. Our analysis shows that year-to-year spatial variability accounts for the substantial difference in the wildfire emission estimates.

JOURNAL	Secondary Organic Aerosol Yields from Cloud-Processing of Isoprene Oxidation Products	01/31/2008

Ervens, B., A. M. CARLTON, B. TURPIN, K. E. Altieri, S. M. Kreidenweis, AND G. Feingold. Secondary Organic Aerosol Yields from Cloud-Processing of Isoprene Oxidation Products. GEOPHYSICAL RESEARCH LETTERS. American Geophysical Union, Washington, DC, 35(L02816):1-20, (2008).
Abstract:	Uncertainties in estimating aerosol direct and indirect effects on climate arise due to the complexity of aerosol properties and their source and sink processes. While these are usually well captured in models for inorganic aerosol constituents, the organic fraction represents a much greater challenge.

JOURNAL	Estimating the Impact of the 2004 Alaskan Forest Fires on Episodic Particulate Matter Pollution Over the Eastern United States Through Assimilation of Satellite Derived Aerosol Optical Depths in a Regional Air Quality Model	09/04/2008

MATHUR, R. Estimating the Impact of the 2004 Alaskan Forest Fires on Episodic Particulate Matter Pollution Over the Eastern United States Through Assimilation of Satellite Derived Aerosol Optical Depths in a Regional Air Quality Model. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES. American Geophysical Union, Washington, DC, 113(D17302):1-14, (2008).
Abstract:	During the summer of 2004, extensive wildfires burned in Alaska and western Canada; the fires were the largest on record for Alaska. Smoke from these fires was observed over the continental United States in satellite images. Recent studies have quantified the impacts of the long-range transport of pollution associated with these fires on tropospheric CO and O₃ levels over the eastern United States. This study quantifies the episodic impact of this pollution transport event on surface-level fine particulate matter (PM_2.5) concentrations over the eastern U.S. during mid-July 2004, through the complementary use of remotely-sensed, aloft, and surface measurements, in conjunction with a comprehensive regional atmospheric chemistry-transport model. Based on the model calculations, a 0.12Tg enhancement in tropospheric PM_2.5 mass loading over the eastern U.S. is estimated on 19 July, 2004 due to the fires. This amount is significantly larger (approximately a factor of 8) than the total daily anthropogenic fine particulate matter emissions for the Continental U.S. Analysis of measured and modeled PM_2.5 surface-level concentrations suggests that the transport of particulate matter pollution associated with the fires resulted in a 24-42 % enhancement in median surface-level PM_2.5 concentrations across the eastern United States during July 19-23, 2004.

JOURNAL	Diagnostic Analyses of a Regional Air Quality Model: Changes in Modeled Processes Affecting Ozone and Chemical-Transport Indicators from No_x Point Source Emission Reductions	10/04/2008

GODOWITCH, J. M., C. Hogrefe, AND S. RAO. Diagnostic Analyses of a Regional Air Quality Model: Changes in Modeled Processes Affecting Ozone and Chemical-Transport Indicators from No_x Point Source Emission Reductions. JOURNAL OF GEOPHYSICAL RESEARCH. American Geophysical Union, Washington, DC, 113(D19303):1-15, (2008).
Abstract:	The impact of nitrogen oxide (NO_x) emission reductions from major point sources on the key physical and chemical processes contributing to ozone formation and accumulation is studied, and the extent of change in the chemical regime is examined using selected photochemical indicators in the eastern United States. The Community Multiscale Air Quality (CMAQ) chemical-transport model, equipped with the process analysis technique, was applied in modeling scenarios involving 2002 base case emissions and an emissions scenario containing real-world point source NO_x reductions implemented before the summer ozone season of 2004. Spatial patterns and temporal variations in process rates and changes in chemical-transport indicators are highlighted from results of summer 2002 days representative of generally southwesterly wind flows across the Midwestern source region with ozone transport toward the northeastern states. Substantial decreases exceeding 50% in O₃ chemical production rates were associated with the largest NO_x point source emission reductions causing declines in ozone concentrations at the surface and aloft in downwind areas. The decreases in the various physical processes and their spatial difference patterns closely resembled the change in maximum O₃ concentrations. The net ozone production efficiency was found to increase since the decline in O₃ concentrations was less than the decrease in reactive nitrogen products (NO_z). The O₃/NO_x ratio also increased between the base case and NO_x reduction scenario results indicating a noticeable shift in the chemical regime towards more NO_x-limited conditions in plume-impacted areas downwind of the sources. The drop in surface NO_x concentrations in modeled and observed results at a location just downwind of the Ohio River Valley source region is attributable to the point source NO_x emission reductions.

JOURNAL	Modeling Analyses of the Effects of Changes in Nitrogen Oxides Emission from the Electric Power Sector on Ozone Levels in the Eastern United States	04/01/2008

Gego, E., A. GILLILAND, J. M. GODOWITCH, S. RAO, P. Porter, AND C. Hogrefe. Modeling Analyses of the Effects of Changes in Nitrogen Oxides Emission from the Electric Power Sector on Ozone Levels in the Eastern United States. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION. Air & Waste Management Association, Pittsburgh, PA, 58(4):580-588, (2008).
Abstract:	This modeling study tests a hypothetical scenario to see what air quality might have looked like if no emission controls had been placed on electric generating units, as required by the NOx State Implementation Plan (SIP) Call required in 2004. Results showed that ozone levels would have been higher and air quality deteriorated noticeably if the controls had not been put in place.

JOURNAL	A Method of Evaluating Spatially-Resolved No_x Emissions Using Kalman Filter Inversion, Direct Sensitivities, and Space-Based No₂ Observations	09/19/2008

NAPELENOK, S., R. W. PINDER, A. GILLILAND, AND R. V. Martin. A Method of Evaluating Spatially-Resolved No_x Emissions Using Kalman Filter Inversion, Direct Sensitivities, and Space-Based No₂ Observations. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, Germany, 8(18):5603-5614, (2008).
Abstract:	An inverse modeling method was developed and tested for identifying possible biases in emission inventories using satellite observations. The relationships between emission inputs and modeled ambient concentrations were estimated using sensitivities calculated with the decoupled direct method in three dimensions (DDM-3D) implemented within the framework of the Community Multiscale Air Quality (CMAQ) regional model. As a case study to test the approach, the method was applied to regional ground-level NO_x emissions in the southeastern United States as constrained by the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) satellite derived observations of NO₂ column densities. A controlled “pseudodata” scenario with a known solution was used to establish that the methodology can achieve the correct solution, and the approach was then applied to a summer 2004 period where the satellite data are available. The results indicate that emissions biases differ in urban and rural areas of the southeast. The method suggested slight downward (less than 10%) adjustment to urban emissions, while rural region results were found to be highly sensitive to NO_x processes in the upper troposphere. As such, the bias in the rural areas is likely not solely due to biases in the ground-level emissions. It was found that CMAQ was unable to predict the significant level of NO₂ in the upper troposphere that was observed during the NASA Intercontinental Chemical Transport Experiment (INTEX) measurement campaign. The reasons for the underestimation likely include combination of a lack of lightning emissions and a short modeled lifetime of NO_x aloft. Therefore, the best correlation between satellite observations and modeled NO₂ column densities, as well as comparison to ground-level observations of NO₂, was obtained from performing the inverse while accounting for the significant presence of NO₂ in the upper troposphere not captured by the regional model.

JOURNAL	The North American Mercury Model Intercomparison Study (Nammis). Study Description and Model-to-Model Comparison	09/09/2008

BULLOCK, R., D. ATKINSON, T. BRAVERMAN, K. Civerolo, A. Dastoor, D. Davignon, J. Ku, K. Lohman, T. C. Meyer, R. J. Park, C. Seigneur, N. E. SELIN, G. Sistla, AND K. Vijayaraghavan. The North American Mercury Model Intercomparison Study (Nammis). Study Description and Model-to-Model Comparison. JOURNAL OF GEOPHYSICAL RESEARCH. American Geophysical Union, Washington, DC, 113(D17310):1-17, (2008).
Abstract:	This manuscript provides a description of the North American Mercury Model Intercomparison Study (NAMMIS) and results obtained from that study. The NAMMIS was conducted by EPA/NERL and involved a number of public and private research organizations developing numerical models of atmospheric mercury. Currently, insufficient observational data exist with which to evaluate atmospheric mercury models in the same way that models of ozone, particulate matter, and acid/nutrient deposition have been evaluated. Previously, atmospheric mercury models have been subjected to intercomparison studies in Europe. With this work, mercury model intercomparison has been performed in North America with an improved method employing a more tightly constrained modeling procedure.

JOURNAL	A Procedure for Inter-Comparing the Skill of Regional-Scale Air Quality Model Simulations of Daily Maximum 8-Hour Ozone Concentrations	07/01/2008

IRWIN, J., K. Civerolo, C. Hogrefe, W. APPEL, K. FOLEY, AND J. SWALL. A Procedure for Inter-Comparing the Skill of Regional-Scale Air Quality Model Simulations of Daily Maximum 8-Hour Ozone Concentrations. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 42(21):5403-5412, (2008).
Abstract:	An operational model evaluation procedure is described to quantitatively assess the relative skill among several regionalscale air quality models simulating various percentiles of the cumulative frequency distribution of observed daily maximum 8-h ozone concentrations. Bootstrap sampling is used to characterize the variability in the observed percentile values, thereby providing a means for assessing whether the differences seen between model predictions are significant. The procedure was designed to facilitate model inter-comparisons, since all that is needed to implement the procedure is for each modeler to provide a listing of the daily maximum 8-h ozone concentration predictions for a summer season for grid cells containing ozone monitors. Available ozone modeling results for the summer of 2002 from four regional-scale air quality simulations are used here to illustrate the results that can be obtained. These simulations were conducted using the Community Multi-Scale Air Quality (CMAQ) model with somewhat different setups. The modeling domains were different, but there is a region in the central Eastern United States where ozone estimates from all four simulations are available. Our objective is to describe the inter-comparison procedure, to illustrate the results obtained, and to stimulate discussions on how similar procedures might be developed and improved in the future.

JOURNAL	Environmental Impact of Atmospheric Nh ₃ Emissions Under Present and Future Conditions in the Eastern United States	06/25/2008

PINDER, R. W., A. GILLILAND, AND R. L. DENNIS. Environmental Impact of Atmospheric Nh ₃ Emissions Under Present and Future Conditions in the Eastern United States. GEOPHYSICAL RESEARCH LETTERS. American Geophysical Union, Washington, DC, 35(L12808):1-6, (2008).
Abstract:	Recent regulations require large-scale emission reductions of NO_x and SO₂ in the eastern United States. These emission changes will alter the partitioning of ammonia between the gas and particle phases. Furthermore, ammonia emissions are expected to increase in the future. How will these changes impact the contribution of ammonia to inorganic particulate matter and nitrogen deposition? We use a chemical transport model and emission scenarios representing years 2001, 2010, and 2020 to estimate the future change of the sensitivity of iPM_2.5to ammonia emission reductions and change in nitrogen deposition to ecosystems. We find that during winter conditions, particulate matter concentrations in several locations in the Midwestern US continue to have significant sensitivity to NH₃ emissions. In addition, the total nitrogen deposition near NH₃ emission sources increases 10 - 40%.

JOURNAL	Characterizing Variability and Uncertainty in Exposure Assessments Improves Links to Environmental Decision-Making	07/01/2008

OZKAYNAK, H. A., C. H. Frey, AND B. HUBBELL. Characterizing Variability and Uncertainty in Exposure Assessments Improves Links to Environmental Decision-Making. EM: AIR AND WASTE MANAGEMENT ASSOCIATIONS MAGAZINE FOR ENVIRONMENTAL MANAGERS. Air & Waste Management Association, Pittsburgh, PA, 16-20, (2008).
Abstract:	Environmental Decisions often rely upon observational data or model estimates. For instance, the evaluation of human health or ecological risks often includes information on pollutant emission rates, environmental concentrations, exposures, and exposure/dose-response data. Whether measured or modeled, each of these elements of information has certain underlying limitations. In addition to basic accuracy and precision issues, spatial and temporal representativeness of data and their applicability to different population or receptor groups of interest are important concerns. Understanding the various sources of variability and uncertainty in exposure risk information is relevant to many types of environmental decision-making, including setting standards, determining emissions controls, and mitigating exposures to pollutants.

JOURNAL	Exposure Science and Its Applications for Effective Environmental Management	07/01/2008

RAO, S. Exposure Science and Its Applications for Effective Environmental Management. EM: AIR AND WASTE MANAGEMENT ASSOCIATIONS MAGAZINE FOR ENVIRONMENTAL MANAGERS. Air & Waste Management Association, Pittsburgh, PA, (July 2008):7, (2008).
Abstract:	Exposure is the link between environmental pollution and human/ecosystem health. Exposure science entails understanding the scientific processes that affect source emissions, transport and fate, spatio-temporal variability in the ambient concentrations, levels of contaminants that people breathe in, and stressors to sensitive ecosystems. This month, EM considers the need for advancing exposure science and its applications to better protect human and ecosystem health, and the resulting challenges confronting environmental managers.

JOURNAL	Assessing Exposure to Waterborne Pathogens	07/01/2008

HAUCHMAN, F. S. Assessing Exposure to Waterborne Pathogens. EM: AIR AND WASTE MANAGEMENT ASSOCIATIONS MAGAZINE FOR ENVIRONMENTAL MANAGERS. Air & Waste Management Association, Pittsburgh, PA, (July 2008):30-32, (2008).
Abstract:	In the U.S, and other developed countries, application of the multi-barrier approach for protecting and treating water supplies has led to the virtual elimination of waterborne threats such as cholera and typhoid. Nevertheless, illnesses associated with contaminated drinking water and recreational water continue to be reported. The actual number of cases of waterborne diseases is likely to be higher than the reported values due to a number of factors, such as the passive nature to the waterborne disease surveillance system in the U.S. and the difficulty in attributing illnesses to waterborne exposures.

PAPER IN NON-EPA PROCEEDINGS	The Impact of Satellite-Derived Biomass Burning Emission Estimates on Air Quality	08/27/2008

POULIOT, G., T. E. PIERCE, X. Zhang, S. Kondragunta, C. WIEDINMYER, T. PACE, AND D. MOBLEY. The Impact of Satellite-Derived Biomass Burning Emission Estimates on Air Quality. In Proceedings, Remote Sensing of Fire: Science and Application, SAn Diego, CA, August 10 - 14, 2008. SPIE/International Society for Optical Engineering, Bellingham, WA, 7089F 1-12, (2008).
Abstract:	Various methods to generate satellite-based biomass burning emission estimates have recently been developed for their use in air quality models. Each method has different assumptions, data sources, and algorithms. This paper compares three different satellite-based biomass burning emission estimates against a controlled case of no biomass burning and ground-based biomass estimate in an air quality model.

PRESENTATION	P2.4 Speciate EPA's Database for Speciated Emission Profiles	09/24/2008

MOBLEY, D., L. BECK, G. SARWAR, A. H. REFF, AND M. HOUYOUX. P2.4 Speciate EPA's Database for Speciated Emission Profiles. Presented at Air Pollution Modeling and its Application XIX, Aveiro, PORTUGAL, September 24 - 28, 2007.
Abstract:	SPECIATE, is the U.S. Environmental Protection Agency’s (EPA) repository of total organic compound (TOC) and particulate matter (PM) speciation profiles for emissions from air pollution sources. The profiles are key inputs to air quality modeling and source-receptor modeling applications. This paper addresses Version 4.0 of the SPECIATE database.

PUBLISHED REPORT	Summary Report of Air Quality Modeling Research Activities for 2006	05/29/2008

RAO, S., R. L. DENNIS, V. GARCIA, A. GILLILAND, R. MATHUR, D. MOBLEY, T. E. PIERCE, AND K. L. SCHERE. Summary Report of Air Quality Modeling Research Activities for 2006. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-07/103 (NTIS PB2008-110094), 2008.
Abstract:	Through a Memorandum of Understanding (MOU) and Memorandum of Agreement (MOA) between the Department of Commerce (DOC) and U.S. Environmental Protection Agency (EPA), the Atmospheric Sciences Modeling Division (ASMD) of National Oceanic and Atmospheric Administration's (NOAA's) Air Resources Laboratory (ARL) develops advanced modeling and decision support systems for effective forecasting and management of the Nation's air quality. As a division within the EPA organizational structure, ASMD is known as the Atmospheric Modeling Division (AMD). The Division is responsible for providing a sound scientific and technical basis for regulatory policies to improve ambient air quality. The models developed by the Division are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations. This report summarizes research and operational activities of the Division for the year 2006.

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