Comparison of measured and modeled ozone distributions over the Atlantic and Pacific Oceans from the ATom mission

The NASA Atmospheric Tomography (ATom) Mission has provided a large data set of chemical and other measurements over the Atlantic, Pacific, Southern, and Arctic Oceans from near the surface to about 12 km in each season. The mission was designed to study the chemistry of the shorter-lived greenhouse gases ozone and methane, atmospheric oxidation, and other chemical cycles over large geographic regions, and to challenge global chemical transport models. I present data and intercomparisons from the ATom deployments here, focusing on ozone, related gas phase species, and results from six different atmospheric models. The model results include years prior to ATom and with meteorology from the ATom time periods (2016-2018), both mapped onto ATom flight tracks and averaged over latitude-longitude-altitude boxes. The goals are to 1) find the distributions of tropospheric ozone along N-S transects across the Atlantic and Pacific Oceans and the polar regions as a function of altitude, latitude, and season, 2) compare with model results both as time series along flight tracks and as probability distributions, and 3) improve our understanding of model-measurement agreement or differences resulting from emissions, chemistry, and transport. All the models examined do a reasonable job of predicting large-scale features in ozone. The NASA Global Modeling Initiative (GMI) chemical transport model performed well in hindcasting ozone distributions over the ATom deployments using actual meteorology. The models tend to overpredict ozone in the tropical free troposphere, both over the Atlantic and the Pacific. This presentation includes data from all the ATom deployments and explores the chemical relationships in models and aircraft data for ozone and related species such as NO_x (NO + NO₂) and CO.