Formic and acetic acids are the predominant carboxylic acids present in the atmosphere, and a major source of acidity in rural and remote areas. Current models generally underpredict the abundance of these species by a factor of two or more, pointing to the existence of at least one large missing source. Here we employ the GEOS-Chem chemical transport model to interpret an ensemble of new in-situ (ground-based and airborne) and space-based (TES onboard EOS Aura) observations in terms of the constraints they can provide on production mechanisms and key precursors of atmospheric carboxylic acids. The in-situ measurements span a variety of urban, rural, agricultural, and forested regions across North America. The space-based formic acid data reveal a severe model underestimate that manifests globally, including over the northern mid-latitudes. The most prominent discrepancy between GEOS-Chem and TES occurs over biomass burning regions, indicating a major missing source of organic acids from fires.

Chemical sources of formic and acetic acids: Insights from ground-, air-, and space-based data

248th National Meeting (2014)

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