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An evaluation of trends and variability in aerosol optical depth over the Northern Hemisphere simulated by CMAQv5.3.2 for the EQUATES project
Citation:
Miller, R., C. Hogrefe, R. Mathur, Jon Pleim, AND K. Foley. An evaluation of trends and variability in aerosol optical depth over the Northern Hemisphere simulated by CMAQv5.3.2 for the EQUATES project. 20th Annual CMAS Conference, NA, NC, November 01 - 05, 2021.
Impact/Purpose:
This abstract describes the analysis of aerosol optical depth (AOD) fields simulated by a hemispheric CMAQ configuration for EPA’s Air QUAlity TimE Series (EQUATES) project over the 2002 – 2017 time period. Analyzing temporal and spatial variations in AOD in conjunction with PM2.5 concentrations at the surface will provide information on the modeling system’s ability to represent aerosol distributions on the hemispheric scale which can then be used to guide future model development.
Description:
Air quality models are important tools for studying atmospheric trace gases and aerosols. Their outputs are often used to quantify adverse impacts of air quality on human health and the environment. Model simulations were performed for 2002–2017 using CMAQv5.3.2 and WRFv4.1.1 over the Northern Hemisphere. Emissions were represented by a 2002–2017 emissions dataset developed for EPA’s Air QUAlity TimE Series (EQUATES) project. In this presentation, we compare these simulations with monthly average aerosol optical depth (AOD) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the NASA Terra satellite to assess the model’s ability to capture observed variability and trends in the tropospheric aerosol burden. Initial findings show regional and seasonal differences between model and satellite observations. Over CONUS, the annual AOD cycle is in general agreement with satellite observations for all seasons, except summer when CMAQ AOD values are lower than observed. Linear trends through the annual average AOD reveal a decrease in AOD over the southeastern United States, Europe, and China, and an increase over India. These linear trends are similar for both the model output and satellite observations. To provide further context for the AOD analysis, we also present an analysis of ground-based AOD from AERONET and PM2.5 concentrations measured at surface monitoring networks over North America and Europe.
