Carlie J. Coats

Emission inventory development and processing for the Seasonal Model for Regional Air Quality (SMRAQ) project

This paper describes the experiences and insights gained from inventory preparation and emissions processing for the Seasonal Model for Regional Air Quality (SMRAQ) project. The emission inventory was derived from the 1990 and 1995 Ozone Transport Assessment Group (OTAG) inventories. Here we outline the emissions processing strategy used for the May-to-September simulation, summarize the inventory characteristics and corrections made on the OTAG inventories, and describe the quality assurance steps taken as part of the processing. We then provide spatial maps and daily total time series charts of the hourly, gridded emissions of nitrogen oxides (NOx), reactive organic gases (ROG), and carbon monoxide (CO). Large peaks from electric utility point sources and urban mobile sources characterize the NOx emissions, and the NOx emissions in nonpeak regions are primarily mobile-source emissions. ROG emissions are dominated by biogenic isoprene production in the southern United States, and they have a strong seasonal variability. CO emissions are characterized by less variability, with area and mobile sources dominating the inventory. We compare ratios of season-average nonmethane organic gases to NOx between the emission inventory and the Photochemical Assessment Monitoring Stations (PAMS) data, and these comparisons show poor correlation between the inventory and ambient ratios.

The next generation of integrated air quality modeling: EPA's models-3

Abstract The U.S. Environmental Protection Agency is developing a third-generation modeling system, termed Models-3. This paper provides an overview of the concepts behind this effort. The modeling challenge is large and is addressed at two main user groups, regulatory analysts and scientists. New technology and tools from the federal High Performance Computing and Communications Program present an opportunity to effectively address computational constraints and the modeling challenge, simultaneously. Two goals of the Advanced Air Quality Modeling Project are (1) provide an effective decision support system and (2) provide a framework to support the evolvement of models and modeling systems. The information needed for a decision support system is described and its elements are defined. The need to be able to significantly evolve the air quality models is discussed next, followed by the presentation of a general software approach for avoiding modeling system obsolescence. In the final section, key modeling considerations and target capabilities are outlined to show the directions being undertaken to initiate Models-3.

A Stochastic Methodology for Regional Wind-Field Modeling

Abstract Three-dimensional, regional scale (≈1000 km) air-quality simulation models require hourly inputs of U and V wind components for each vertical layer of the model and for each grid cell in the horizontal. The standard North American meteorological observation network is used to derive the wind-field inputs for the U.S. Environmental Protection Agencys Regional Oxidant Model (ROM) and other regional models. While a fairly dense surface network with hourly observations exists, upper-air data are obtained only twice per day at monitoring sites typically separated by distances of 300–500 km. Using these data to derive the more spatially and temporally resolved gridded wind fields needed by the ROM introduces uncertainties and errors into the model. We present a method of developing gridded wind fields for the ROM that accounts for these nondeterministic features. The method produces a family of potential gridded wind fields that allows for the stochastic nature of the interpolation process. Examples o...