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Insights into modeled elevated O3 over water bodies
Citation:
Bash, J., D. Schwede, W. Appel, AND H. Pye. Insights into modeled elevated O3 over water bodies. Lake Michigan Ozone Study, Durham, NC, June 19, 2018.
Impact/Purpose:
This is a briefing on the impact of changes to the Community Multiscale Air Quality (CMAQ) model's atmospheric deposition on coastal ozone concentrations for the upcoming v5.3 release of the model. Changes in the dry deposition of transported species, mostly organics, has resulted in large reductions in the biases in ozone at coastal monitoring sites. This presentation presents some insights into the cause of this model improvement.
Description:
Dry deposition in the Community Multiscale Air Quality (CMAQ) model will be expanded to include all transported species for the v5.3 release. Prior to this only a subset of species were dry deposited. These species consist primarily of , organic nitrates, terpenes, open ring aromatics, alkenes, aldehydes, organic acids, ketones, ClNO2. The deposition of these species was limited to wetted surfaces as we expect many of these species to not deposit or originate from vegetation and soil surfaces. For the most part this did not significantly change air quality model results. However, we document instances here where the combination of deposition, atmospheric chemistry and transport have significantly reduced coastal ozone concentrations during ozone events. This has resulted in a dramatic reduction in model bias and error at coastal monitoring sites.