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PAST, PRESENT AND FUTURE AIR QUALITY MODELING AND ITS APPLICATIONS IN THE UNITED STATES
Citation:
Rao, S T., J. Irwin, K L. Schere, T E. Pierce Jr., R L. Dennis, AND J.K S. Ching. PAST, PRESENT AND FUTURE AIR QUALITY MODELING AND ITS APPLICATIONS IN THE UNITED STATES. Presented at 8th International Conference on Atmospheric Sciences and Application to Air Quality, Tsukuba, Japan, March 11-13, 2003.
Impact/Purpose:
The objectives of this task are to continuously develop and improve EPA's mesoscale (regional through urban scale) air quality simulation models, such as the Community Multiscale Air Quality (CMAQ) model, as air quality management and NAAQS implementation tools. CMAQ is a multiscale and multi-pollutant chemistry-transport model (CTM) that includes the necessary critical science process modules for atmospheric transport, deposition, cloud mixing, emissions, gas- and aqueous-phase chemical transformation processes, and aerosol dynamics and chemistry. To achieve the advances in CMAQ, research will be conducted to develop and test appropriate chemical and physical mechanisms, improve the accuracy of emissions and dry deposition algorithms, and to develop and improve state-of-the-science meteorology models and contributing process parameterizations.
Description:
Since the inception of the Clean Air Act (CAA) in 1969, atmospheric models have been used to assess source-receptor relationships for sulfur dioxide and total suspended particulate matter (TSP) in the urban areas. The focus through the 1970's has been on the Gaussian dispersion models for non-reactive pollutants. The 1977 Amendments to the CAA mandated the use of dispersion models for assessing compliance with the relevant National Ambient Air Quality Standards (NAAQS) when new sources of pollution are permitted and for prevention of significant deterioration. In the 1980's, the focus has been on the secondary pollutants (e.g., ozone, acid rain), which led to the development of grid-based photochemical models to better understand the urban and regional scale pollution. In the 1990's, attention was paid to the development of one-atmosphere models to deal with multiple pollutants. The new NAAQS for ozone and fine particulate matter (PM 2.5) that were promulated in the 1997 call for the use of one-atmosphere models in designing multi-pollutant emission control strategies. In the 2000's, there is a considerable interest in the development of integrated airshed-watershed models to properly assess the effects of atmospheric pollution on sensitive ecosystems. Air quality models can help improve our understanding of the transport and fate of pollutants, and are essential tools for designing meaningful and effective emission control strategies. Future applications of air quality models will be towards the prediction and improved understanding of human exposure, especially in urban areas, and intercontinental-cross oceanic hemispheric air pollutant transport.