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The Future of EPA’s Air Quality Time Series
Citation:
Pouliot, G., K. Foley, A. Eyth, J. Vukovich, V. Rao, C. Farkas, AND J. Godfrey. The Future of EPA’s Air Quality Time Series. 2023 International Emissions Inventory Conference - The Nexus of Climate, Air Quality and Health: Smoke and Other Emissions Challenges, Seattle, WA, September 26 - 29, 2023.
Impact/Purpose:
EPA scientists have developed a set of modeled meteorology, emissions, air quality and pollutant deposition spanning the years 2002 through 2019. Modeled datasets cover the Conterminous U.S. (CONUS) at a 12km horizontal grid spacing and the Northern Hemisphere at a 108km grid spacing using the Weather Research and Forecasting (WRF) model version 4.1.1 for simulating weather conditions and EPA’s Community Multiscale Air Quality (CMAQ) model version 5.3.2 for air quality modeling. New hemispheric and North American emissions inventories were developed using, to the extent possible, consistent input data and methods across all years, including emissions from motor vehicles, fires, and oil and gas sources. Decadal CMAQ simulations have been used for epidemiological studies, critical loads analyses, and to understand local and global air quality trends. EQUATES supersedes previous CMAQ time series and provides a unified set of modeling data in order to: Reduce artificial step changes in model estimates due to changes in methodology, e.g., input data, processing methods, model versions Provide information on trends in criteria pollutants (e.g., ozone, particulate matter, nitrogen oxides) for epidemiologists Provide information on deposition trends for EPA’s EnviroAtlas, the National Atmospheric Deposition Program’s Total Deposition (NADP TDep) maps and grids, and to support critical loads studies and nutrient assessments Facilitate dynamic and diagnostic model evaluation with consistent modeling data and provide a base modeling platform for sensitivity simulations to support model development Share modeling datasets on a public online platform so that collaborators in and outside of EPA can leverage the modeling products for their work
Description:
The EPA has developed a set of modeled meteorology, emissions, air quality and pollutant deposition spanning the years 2002 through 2019, known as EPA’s Air Quality Time Series (EQUATES). The emission inventory data for this time series was a key component of this large project. The key goal was to develop North American emissions inventories using, to the extent possible, consistent year-specific input data and the most up to date methods across all years, including emissions from motor vehicles, fires, and oil and gas sources. Now that this dataset is available for use and has been incorporated into many modeling studies and into the latest release of the EPA air emission trends data in 2023, (https://www.epa.gov/air-emissions-inventories/air-pollutant-emissions-trends-data), we will provide an overall summary of the project, lessons learned, and ideas for the next steps for EPA’s time series project. When new and improved inventory methods are developed in the future for any sector, we would need to update the current EQUATES dataset for 2002-2019 to a new version. In addition, looking ahead to the current decade that started in 2020, we will likely at some point want to develop a new time series starting in 2020 that would incorporate the latest information and methods for inventory development, possibly including inventory improvements derived from NASA’s Tropospheric Emissions: Monitoring of Pollution (TEMPO) satellite that was launched in April 2023 and adding hazardous air pollutants (HAPs) trends to the suite of these criteria air pollutants (CAPs).