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IMPROVED EUTROPHYING AND ACIDIFYING DEPOSITION ALGORITHMS IN CMAQ
Improve the understanding of the interaction of the atmosphere and the underlying surface and EPA's ability to simulate that interaction.
A long term goal of multimedia environmental management is to achieve sustainable ecological resources. Progress towards this goal rests on a foundation of science-based methods and data integrated into predictive multimedia, multi-stressor open architecture modeling systems. The strategic pathway aims at progressing from addressing one stressor at a time to a comprehensive multimedia assessment capability for current and projected ecosystem health. The multimedia tasks in the Atmospheric Modeling Division (AMD) address a number of issues that arise in multimedia modeling with an emphasis on interactions among the atmosphere and other environmental media. While the watershed is a fundamental unit of ecosystem analysis, due primarily to its containment of the hydrologic cycle and related stresses, the relevant atmospheric scale of modeling and analysis for linking to watersheds is regional/continental in scope, encompassing multiple States and/or watersheds. The interaction between the atmosphere and the underlying surface is increasingly being recognized as an important factor in multimedia issues. Targeted development, evaluation and application of state-of-the-art, multi-pollutant atmospheric models of ozone, sulfur dioxide, nitrogen and mercury to multimedia issues help determine how to further improve the one-atmosphere models and support ongoing ecological assessments. Software tools are needed to support linkage of models across media and specialized multimedia data analysis applications. This multimedia work helps to bring the results of air pollution control, that primarily stem from addressing human health effects, into the management purview for addressing multimedia or ecosystem problems. The AMD multimedia tasks support Goal 4 (Healthy Communities and Ecosystems) and its Long-Term Goals ECO-6, Forecasting - Assess vulnerability and manage for sustainability, and HG-3, Transport and fate - understand the transport and fate of mercury from release to the receptor.
The interaction between the atmosphere and the underlying surface is increasingly recognized as important. A key output of atmospheric models for multimedia studies is the dry deposition component of total deposition (wet + dry). There is an extreme paucity of empirical dry deposition estimates for use with ecosystem management modeling. The estimates from the atmospheric models fill a critical gap. A targeted focus on creating state-of-the-science dry deposition algorithms for the air quality models has significant importance to multimedia studies. This is an area of strong collaboration between Community Multiscale Air Quality (CMAQ) model development and the multimedia program. Two chemical species modeled using CMAQ that are of particular interest with respect to ecosystem effects and also have great modeling uncertainty are NH3 and SO2. Dry deposition of particles is also an important contributor to ecosystem loading. Recent field studies by Meyers of NOAA-Oak Ridge have shown surprisingly large deposition velocities for particles when compared to theoretical estimates. The work on this task will focus on improving our estimates of the dry deposition of these pollutants.