HR: 1340h
AN: GC33A-0952    [Abstracts]
TI: Impact of geo-engineered aerosols on stratospheric composition and dynamics
AU: * Tilmes, S
EM: tilmes@ucar.edu
AF: National Center Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000, United States
AU: Garcia, R
EM: rgarcia@ucar.edu
AF: National Center Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000, United States
AU: Kinnison, D
EM: dkin@ucar.edu
AF: National Center Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000, United States
AU: Gettelman, A
EM: andrew@ucar.edu
AF: National Center Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000, United States
AU: Rasch, P
EM: pjr@ucar.edu
AF: National Center Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000, United States
AB: A recently proposed geo-engineering scheme to limit greenhouse warming is the injection of sulfur into the stratosphere to increase the Earth's albedo. This is expected to reduce tropospheric temperatures, as observed following large volcanic eruptions (for example, Mt. Pinatubo in June of 1991). However, that eruption also enhanced stratospheric ozone loss in the Arctic lower stratosphere via heterogeneous processes on sulfate aerosols. The impact of artificially enhancing the sulfate layer on chemical ozone loss can be estimated roughly for future chlorine conditions in the stratosphere. However, such estimates do not predict radiative effects, or the entire range of changes in stratospheric composition, dynamics and temperature. Here, we present first results of a transient climate simulation with enhanced anthropogenic sulfate aerosols using a 3D coupled Chemistry Climate Model, the Whole Atmosphere Community Climate Model (WACCM). In contrast to previous model studies, the impacts on stratospheric chemistry, including heterogeneous chemistry in the polar region are considered in this simulation. Changes in chemistry also affect the radiation budget and feed back on atmospheric transport. Further, interactions between atmospheric and ocean temperatures are included in this simulation, which includes a coupled slab ocean model. We assume a stratospheric distribution of volcanic-like liquid sulfate aerosols consistent with the injection of 2 Tg S/year, as calculated by the NCAR Community Atmosphere Model (CAM3). Using WACCM, we expect significant changes in composition, especially ozone depletion in the Northern Hemisphere for cold Arctic winters, and corresponding changes in dynamics and temperatures in the stratosphere and troposphere.
DE: 0340 Middle atmosphere: composition and chemistry
DE: 0341 Middle atmosphere: constituent transport and chemistry (3334)
DE: 0370 Volcanic effects (8409)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting