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Community Multiscale Air Quality (CMAQ) estimates of long term trends in meteorology, emissions, air quality, and deposition
Citation:
Foley, K. AND G. Pouliot. Community Multiscale Air Quality (CMAQ) estimates of long term trends in meteorology, emissions, air quality, and deposition. The Global Emissions InitiAtive (GEIA) 2020 Web Conference, NA, June 23 - 24, 2020.
Impact/Purpose:
The Community Multiscale Air Quality modeling system (CMAQ; https://www.epa.gov/cmaq) estimates atmospheric concentrations and deposition for numerous chemicals, including ozone, PM2.5 and its constituents, and deposition of important nitrogen and sulfur species. CMAQ concentration and deposition values are used to produce the National Atmospheric Deposition Program Total Deposition (TDep) maps and grids. The current TDep maps are based on a time series (2002-2012) of values from CMAQ v5.0.2. Similarly, time series of CMAQ deposition values are provided as a data layer by EPA’s EnviroAtlas and are also used to support many nutrient assessments included those for the Chesapeake Bay, Mississippi River Basin, Tampa Bay, and the Nooksack Fraser Transboundary region. Decadal CMAQ estimates are also used by OAQPS in their model-observation “fused” maps of ozone and PM2.5. These fused surfaces are part of the CDC’s National Environmental Public Health Tracking Network and have been used in numerous time-series based epidemiological studies by researchers in and outside of EPA to link air quality to a variety of different health effects. The modeling from this project using the most recent version of CMAQ, version 5.3, will be used to update these various data products (e.g. TDep maps, EnviroAtlas deposition layers, OAQPS fused ozone and PM2.5 surfaces, Chesapeake Bay model needed for 2025 TMDL). CMAQ v5.3 contains many important science updates which can impact both concentration and deposition. These updates are expected to improve the estimation of trends in these pollutants. Additionally, the new time series will extend from 2002-2017 which will provide year specific data for the recent years that has not been available previously. For example, currently the TDep maps for years later than 2012 use the 2012 CMAQv5.0.2 data.
Description:
The US EPA is developing a set of modeled meteorology, emissions, air quality and pollutant deposition from 2002 through 2017. Modeled datasets will cover the Conterminous US at a 12km resolution and the northern hemisphere at a 108km resolution using WRFv4.1.1 for meteorology and CMAQv5.3.1 for air quality modeling. New hemispheric and North American emissions inventories are being developed using, to the extent possible, consistent input data and methods across all years. US EPA is collaborating with Environment and Climate Change Canada to include their new emissions trends data. The new emissions datasets and CMAQ output will be made publicly available to support a wide variety of human health and ecological applications. For example, modeled deposition will be used by the National Atmospheric Deposition Program (NADP) Total Deposition Science Committee (TDEP) to estimate total sulfur and nitrogen deposition for use in critical loads and other ecological assessments. Model estimated trends will be used for dynamic and diagnostic evaluation of the CMAQ system to inform model development and build confidence in the use of the model for quantifying the impact of meteorological and emissions changes on air quality.
