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Scientific and Structural Developments in CMAQv5.3
Citation:
Murphy, B., W. Appel, J. Bash, K. Fahey, B. Henderson, Bill Hutzell, D. Kang, D. Luecken, R. Mathur, S. Napelenok, Chris Nolte, H. Pye, Jon Pleim, M. Qin, L. Ran, S. Roselle, G. Sarwar, D. Schwede, Q. Shu, AND T. Spero. Scientific and Structural Developments in CMAQv5.3. 2018 CMAS Conference, Chapel Hill, North Carolina, October 22 - 24, 2018.
Impact/Purpose:
This presentation documents the improvements made to the CMAQ model that are incorporate in version 5.3, which will be released in Beta October 2018. The audience for this presentation will comprise mostly users and stakeholders of CMAQ or its data. Thus, the main purpose of this talk is to inform the audience about likely changes to their CMAQ-based air quality analyses and alert to them to features that they will find useful for their research and integration efforts.
Description:
The Community Multiscale Air Quality (CMAQ) model has undergone substantial improvements in its representation of the sources and sinks of atmospheric pollutants. This paper will motivate and explain the major updates in the context of the overall model framework for predicting speciated particulate matter, ozone and other regulated pollutants. Examples of important updates include a new aerosol processing module (AERO7), implementation of halogen chemistry (simple and detailed) and dimethyl-sulfide chemistry, a new version of AQCHEM-KMT taking into account more inorganic/organic chemistry, support for multiple deposition approaches including the new Surface Tiled Aerosol Gas Exchange (STAGE) scheme for pollutant deposition, updates to the M3Dry deposition scheme, thorough revision of infrastructure for emissions input and scaling, improvements to standard and diagnostic outputs, a new release of MCIPv5.0, and many other advances. The extensive additions to AERO7 allow CMAQ to treat the source-specific volatility of combustion-derived OA compounds (e.g. gas and diesel vehicles, wildfires, residential wood combustion, prescribed burns, etc), include the partitioning of water to the particulate organic phase, and represent the high degree of secondary organic aerosol (SOA) production observed from monoterpene precursors in the ambient atmosphere and laboratory studies. We will show preliminary impacts of the most important changes on model performance, but discussion will primarily focus on the assumptions that are needed or relaxed by the inclusion of the new model techniques. The developments we discuss will be available to the community prior to the meeting via the release of a Beta version of CMAQv5.3 (CMAQv5.3.b1), and we encourage feedback and testing by the community. We will also lay out the current and ongoing priorities for further development and characterization that are identified by the EPA CMAQ model development team and the schedule for the public release of CMAQv5.3.
