P3.3 Sensitivity of the Amundsen / Bellingshausen Seas Low to stratospheric polar ozone depletion

Monday, 2 May 2011
Kennedy Room (1st Floor) (Omni Parker House )
Elizabeth A. Zbacnik, Ohio University, Athens, Ohio; and R. L. Fogt

The Amundsen-Bellingshausen Seas Low (ABSL), a semi-permanent low pressure off the coast of West Antarctica, has important monthly and seasonal variations that are not yet currently understood. Since these variations may be related to the marked warming and sea ice loss in the region, it is necessary to further characterize them. A recent study suggested that at least some of the ABSL variations are tied to stratospheric polar ozone depletion. The main goal of the current project is to determine the sensitivity of the ABSL to ozone depletion in climate models that more accurately depict the stratosphere and the effects of atmospheric chemistry on the general circulation. Our analysis is conducted using data from chemistry-climate models from the Stratospheric Processes and their Role in Climate (SPARC) Chemistry-Climate Model Validation project phase 2 (CCMVal2), paying particular attention to the vicinity of the ABSL [45°-75°S; 180°-60°W]. Surface pressure and geopotential height at various pressure levels for the last 50 years are compared in models that incorporate ozone depletion to sensitivity simulations where ozone levels are held constant. The model simulations are also compared to reanalysis datasets from NNR, ERA-40 and JRA-25 for the same purpose, as well as to evaluate each model's mean state. While there are intermodel differences, we note that ozone depletion has had a significant impact on the ABSL, but only in certain months. Results from this study, as well as from future studies focused on other stratospheric processes, can help to uncover the nature of the ABSL and increase our understanding of it, which will ultimately unlock the role the ABSL has played in the dramatic climate changes in the region.
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