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Evaluation of the Community Multiscale Air Quality (CMAQ) Model Version 5.3 Release for the United States
Citation:
Appel, Keith, C. Hogrefe, K. Foley, B. Murphy, H. Pye, J. Bash, J. Pleim, S. Roselle, AND R. Mathur. Evaluation of the Community Multiscale Air Quality (CMAQ) Model Version 5.3 Release for the United States. ITM 2019 - 37th International Technical Meeting On Air Pollution Modelling and it's Application, Hamburg, GERMANY, September 23 - 27, 2019.
Impact/Purpose:
This work presents an evaluation of the latest release of the Community Multiscale Air Quality (CMAQ) model. The CMAQ model is a state-of-the-science air quality model used across the globe to perform air quality modeling for regulatory impact assessments, scientific studies and air quality forecasting. Every new release of the CMAQ model is thoroughly evaluated to provide the community with important information regarding model updates and significant changes in model performance that can be expected when using the new model. Presentations such as this provide an opportunity to share the evaluation results with the scientific community and stakeholders so they know how best apply the new model.
Description:
In the summer 2019, the United States Environmental Protection Agency (USEPA) will release the latest version of the Community Multiscale Air Quality (CMAQ) model. The CMAQ model is a comprehensive, state-of-the-science chemical transport model capable of simulating the emission, transformation, transport, and deposition of numerous gas and particle species, including criteria pollutants such as ozone and particulate matter, and has been used in numerous application across the globe over the past decades. This latest version of the CMAQ model, 5.3, includes a wide range of scientific and structural updates to the current version of the model released several years ago. Examples of these updates include a new version of the aerosol module (AERO7), which improves the simulation of secondary organic aerosol (SOA) particle formation in the atmosphere through updates to the monoterpene SOA parameterization, improved consistency of SOA pathways across chemical mechanisms, and the addition of uptake of water onto hydrophilic organics. The M3DRY deposition scheme has been updated to improve the deposition of gases and bi-directional exchange of ammonia at the surface. In addition to the updates to M3DRY, a new dry deposition scheme, the Surface Tiled Aerosol and Gaseous Exchange (STAGE), is available for the first time in CMAQv5.3. STAGE allows for land-use specific dry deposition estimates which are very important for terrestrial and aquatic ecosystem health applications such as simulations of critical loads and total maximum daily load (TMDL). In addition to these science updates, new emissions scaling capability allows user to easily adjust emission inputs and test emission reduction scenarious. Here we will present a comprehensive evaluation of the new model using 2016 annual simulations for the contiguous United States, comparing the new model version to the previous model version and to observations, focusing on the performance of ozone and particulate matter.