Enhanced Upper Tropical Tropospheric COS: Impact on the Stratospheric Aerosol Layer

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Science  11 Apr 2003:
Vol. 300, Issue 5617, pp. 307-310
DOI: 10.1126/science.1080320

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Carbonyl sulfide (COS) is considered to be a major source of the stratospheric sulfate aerosol during periods of volcanic quiescence. We measured COS at the tropical tropopause and find mixing ratios to be 20 to 50% larger than are assumed in models. The enhanced COS levels are correlated with high concentrations of biomass-burning pollutants like carbon monoxide (CO) and hydrogen cyanide (HCN). The analysis of backward trajectories and global maps of fire statistics suggest that biomass-burning emissions transported upward by deep convection are the source of the enhanced COS in the upper tropical troposphere.

  • * To whom correspondence should be addressed. E-mail: jnotholt{at}

  • Present address: University of Washington, Seattle, WA 98195–1640, USA.

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