1. NASA Ames Research Center, Moffett Field, California 94035, USA
2. Harvard University, Cambridge, Massachusetts 02138, USA
3. University of California, Irvine, California 92697, USA
4. University of Rhode Island, Narragansett, Rhode Island 02882, USA

Correspondence to: H. Singh¹ Correspondence and requests for materials should be addressed to H.S. (e-mail: Email: hsingh@mail.arc.nasa.gov).

Abstract

The presence of oxygenated organic compounds in the troposphere strongly influences key atmospheric processes. Such oxygenated species are, for example, carriers of reactive nitrogen and are easily photolysed, producing free radicals^{1, 2, 3}—and so influence the oxidizing capacity and the ozone-forming potential of the atmosphere^{4, 5, 6}—and may also contribute significantly to the organic component of aerosols^{7, 8}. But knowledge of the distribution and sources of oxygenated organic compounds, especially in the Southern Hemisphere, is limited. Here we characterize the tropospheric composition of oxygenated organic species, using data from a recent airborne survey⁹ conducted over the tropical Pacific Ocean (30° N to 30° S). Measurements of a dozen oxygenated chemicals (carbonyls, alcohols, organic nitrates, organic pernitrates and peroxides), along with several C₂–C₈ hydrocarbons, reveal that abundances of oxygenated species are extremely high, and collectively, oxygenated species are nearly five times more abundant than non-methane hydrocarbons in the Southern Hemisphere. Current atmospheric models are unable to correctly simulate these findings, suggesting that large, diffuse, and hitherto-unknown sources of oxygenated organic compounds must therefore exist. Although the origin of these sources is still unclear, we suggest that oxygenated species could be formed via the oxidation of hydrocarbons in the atmosphere, the photochemical degradation of organic matter in the oceans, and direct emissions from terrestrial vegetation.