Pollutants in the Remote Atmosphere in the Atmospheric Tomography Experiment: Source Attribution and Impacts on Chemical Composition

Pollutants emitted in the topics and subtropics can affect the composition of the troposphere very far from the source regions. Emissions from biomass fires are particularly significant as sources of pollutants found in the most remote parts of the South Pacific and Southern Oceans. During the global flights of the Atmospheric Tomography Mission (ATom), the DC-8 measured remarkably high pollutant concentrations in these very remote southern locations arising from emissions from South America, Australia, and Indonesia. This paper assesses the quantitative influence of emissions from these regions on atmospheric chemistry, including attribution to sources, transit times, chemical aging, and impacts on photochemical processes and rates. These very widespread, low-concentration pollutants can potentially affect global levels of ozone and concentrations of radiatively important species such as black carbon and methane.