P1.8 Characteristics of strong cyclone events in the vicinity of the Amundsen / Bellingshausen Seas Low

Monday, 2 May 2011
Rooftop Ballroom (15th Floor) (Omni Parker House )
Alex J. Wovrosh, Ohio University, Athens, OH; and R. L. Fogt and R. A. Langen

Recent advances in Antarctic climate have led to a better understanding of the synoptic variability of the Southern Ocean. Studies have also noted dramatic warming throughout West Antarctica and on the Antarctic Peninsula. Our project seeks to connect these activities by linking variations of the Amundsen – Bellingshausen Seas Low (ABSL) with the underlying synoptic variability. Of particular interest are the top ten strongest cyclone events, as these events most dramatically impact the regional climate (i.e., temperature, sea ice, precipitation) and influence the climatological ABSL. Using The University of Melbourne's automated cyclone tracking scheme, these top ten strongest cyclone events are based on NNR, ERA-40, and JRA-25 atmospheric reanalysis data sets. Specific emphasis was placed within 45° -75°S, 180° - 60°W, the region of the ABSL, during the years 1979 - 2001. Key properties of the ABSL, such as exact locations of cyclogenesis and minimum central surface pressures (some lower than 930mb) are analyzed. Through statistical tests, these top ten cyclones were then compared to the climatological mean pressure (i.e., the ABSL), unveiling significant differences that highlight anomalous conditions across the midlatitudes and throughout the region which give rise to these intense cyclones. Importantly, in many cases the difference field resembles a positive Southern Annular Mode (SAM) pattern, indicating that the anomalous high pressure through the midlatutides may actually influence the track of these top ten cyclones. Understanding these strongest cyclone events will allow for an improved understanding of their impacts on the region, along with the predictability of future, strong events and the climatological ABSL itself.
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