Strat-Trop CCM - Coupled Stratosphere-Troposphere Chemistry-Climate Model Studies
Principal Investigator: Martyn Chipperfield and Wenshou Tian
Sponsor: NERC
Start Date: Jul 2005
End Date: Dec 2008
Description
A strong, two-way coupling is known to exist between climate change and changes in atmospheric composition. Past studies have shown that there are significant deficiencies in our understanding of the chemical coupling of the stratosphere and troposphere and hence our ability to produce accurate, quantitative estimates of the future composition of the stratosphere and troposphere. This is limited by the neglect of either tropospheric or stratospheric chemistry in coupled chemistry-climate models (CCMs).
This project will produce a new, computationally efficient and detailed stratosphere-troposphere CCM based on the Met Office Unified Model. The CCM will use the stratospheric chemistry scheme from the SLIMCAT CTM and the tropospheric code from the STOCHEM version of the UM. The project will then use the new model to:
- Study the impact of the transport of very short-lived species (VSLS) from the troposphere to the stratosphere and quantify the effect of bromine in the lowermost stratosphere on past and future O3 changes.
- Assess the impact of future changes in stratospheric O3 and other species on the troposphere, specifically changes in stratosphere-troposphere exchange and changes in UV flux reaching the lower atmosphere.
- Conduct and analyse fully coupled runs from 2000-2100 to place in context the roles of changing anthropogenic emissions (of both tropospheric ozone precursors and stratospheric ozone depleters), climate change, and to identify important feedbacks in the coupled system.
The project is a collaboration between ICAS and the University of Edinburgh School of Geosciences (Co-I: David Stevenson).
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