Global distributions of carbonyl sulfide in the upper troposphere and stratosphere

Abstract

We present the first upper tropospheric and stratospheric global distributions of carbonyl sulfide (OCS) observed from space using solar occultation measurements made by the Atmospheric Chemistry Experiment (ACE) satellite Fourier transform spectrometer during 2004-2006. We observe high OCS mixing ratios (>400 pptv) within the tropical stratosphere owing to convected tropospheric air. Stratospheric mixing ratios decrease more rapidly with altitude moving away from the Equator, creating a poleward gradient. Elevated OCS concentrations observed at low southern latitudes are consistent with a significant pyrogenic source. Using coincident ACE measurements of CFC-11 and CFC-12 we determine a global OCS stratospheric lifetime of 64 ± 21 years corresponding to a stratospheric sink of 63-124 Gg OCS yr-1. Copyright 2008 by the American Geophysical Union.