Citation:

Benish, S., J. Bash, K. Foley, C. Hogrefe, AND Keith Appel. Atmospheric Deposition from EPA’s Long-term Air Quality Simulations. NC State Postdoc Symposium, Virtual, Virtual, May 17 - 21, 2021.

Impact/Purpose:

Chemical transport models, including the Community Multiscale Air Quality (CMAQ, https://www.epa.gov/cmaq) modeling system, estimate atmospheric concentrations and nutrient deposition of many pollutants, including nitrogen and sulfur species that contribute to the atmospheric aerosol burden, nutrient deposition and soil acidification. Multiyear CMAQ simulations are used by stakeholders and partners to produce total deposition maps and grids for use in critical loads and ecological evaluation and to develop nutrient assessments and other data products, but are missing deposition values for more recent years and have inconsistencies in model inputs between years. The EPA’s Air QUAlity TimE Series Project (EQUATES) will provide a unified set of multiyear (2002-2017) modeling data by employing the most recent version of CMAQ, version 5.3.2, and a consistent modeling framework that will be useful for many applications. CMAQv5.3.2 incorporates important science updates that may alter deposition estimates, including the first opportunity to assess deposition across different ecosystems.

Description:

Chemical transport models, including the Community Multiscale Air Quality (CMAQ, https://www.epa.gov/cmaq) modeling system, estimate atmospheric concentrations and nutrient deposition of many pollutants, including nitrogen and sulfur species that contribute to the atmospheric aerosol burden, nutrient deposition and soil acidification. Multiyear CMAQ simulations are used by stakeholders and partners to produce total deposition maps and grids for use in critical loads and ecological evaluation and to develop nutrient assessments and other data products, but are missing deposition values for more recent years and have inconsistencies in model inputs between years. The EPA’s Air QUAlity TimE Series Project (EQUATES) will provide a unified set of multiyear (2002-2017) modeling data by employing the most recent version of CMAQ, version 5.3.2, and a consistent modeling framework that will be useful for many applications. CMAQv5.3.2 incorporates important science updates that may alter deposition estimates, including the first opportunity to assess deposition across different ecosystems. The EQUATES simulations will be compared to measurements from the National Atmospheric Deposition (NADP) program and the Clean Air Status and Trends Network (CASTNET) and previous multidecadal simulations. The driving factors for changes in deposition estimates between EQUATES and previous simulations will be discussed. Future work will utilize the updated Integrated Source Apportionment Method (ISAM) tool in CMAQv5.3.2 to quantify atmospheric deposition from different emission sectors and source regions to the Chesapeake Bay Watershed. As one of the first operations of ISAM, this work will demonstrate appropriate applications for air quality management.

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