Response of Antarctic Peninsula Mesoscale Cyclones to the Southern Hemisphere Annular Mode: Potential Linkages to Climate Change
Abstract
The Western Antarctic Peninsula (WAP) is a region that has undergone significant climate change. The WAP region has experienced the largest regional climate warming over the past half century. There has been a concomitant trend in the Southern Annular Mode (SAM) toward a positive polarity: several modeling studies have revealed that a combination of springtime ozone depletion and greenhouse gas increases are primarily responsible. Here we investigate possible linkages with mesoscale cyclone activity in the WAP region, as a potential climate system feedback mechanism. We have analyzed 7066 satellite images from the U.S. Antarctic Program satellite tracking facility at Palmer Station, Antarctica, comprising between 2-14 overpasses per day during 1991-94 (a time interval of large SAM variability). These images allow us to reliably identify and track mesoscale cyclones. The frequency of mesoscale cyclones in the WAP region during is found to be correlated with the SAM index, most strongly during winter and spring. Also, during periods of positive SAM index polarity there is a shift in the storm tracks to favor more east-bound trajectories, consistent with strengthening of circumpolar westerlies. The presence of mesoscale cyclones is associated with positive near-surface-air temperature anomalies in the WAP region year-round, largest during winter. Mesoscale cyclones may therefore have a significant indirect effect on climate change in the WAP region.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.C41A0498L
- Keywords:
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- 0758 Remote sensing;
- 1621 Cryospheric change (0776);
- 3349 Polar meteorology;
- 9310 Antarctica (4207)