Biogenic and anthropogenic carbonyl sulfide as main source of stratospheric background aerosol and its impact on climate
Abstract
A multiyear study with the modular atmospheric chemistry circulation model EMAC with the aerosol module GMXe and high vertical resolution demonstrates that the most abundant sulfur gas in the atmosphere COS is to a large degree responsible for the formation of the stratospheric background aerosol. The model consistently uses the same parameters in the troposphere and stratosphere for the 7 aerosol modes applied. Lower boundary conditions for COS and other longlived gases are taken from observations. We show comparisons with satellite data for aerosol extinction (e.g. SAGE) as well as for SO2 in the middle atmosphere (e.g. ATMOS) and COS. This includes the variation induced by the Quasi-Biennial Oscillation which is internally generated by the model. We also show that organic aerosol contributes significantly to aerosol in the lowermost tropical stratosphere. The radiative impacts of COS and of the COS-induced aerosol will be discussed. Globally, the effects of the anthropogenic contribution of COS on radiative forcing almost cancel. We show that the model is also able to simulate aerosol from SO2 injected by big volcanic eruptions including its radiative effects and implications for geoengineering applications.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.A11F0143B
- Keywords:
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- 0305 ATMOSPHERIC COMPOSITION AND STRUCTURE / Aerosols and particles;
- 0340 ATMOSPHERIC COMPOSITION AND STRUCTURE / Middle atmosphere: composition and chemistry;
- 0370 ATMOSPHERIC COMPOSITION AND STRUCTURE / Volcanic effects;
- 1622 GLOBAL CHANGE / Earth system modeling