Changes in the Atmospheric Circulation Across the Amundsen Sea Region in Relation to Changes in the West Antarctic Ice Sheet

Monday, 15 December 2014
Mark W Seefeldt1, Melissa A Nigro1 and John J Cassano2, (1)Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, (2)Univ Colorado, Boulder, CO, United States
The thinning of the glaciers in the Amundsen Sea sector of West Antarctica, and the corresponding contribution to global sea level rise, has received a large amount of attention in recent years. Previous studies have hypothesized that changes in atmospheric circulation have increased deep-water, onshore Ekman transport in the Amundsen Sea, bringing warm ocean currents to the base of the glaciers. This change in ocean currents is considered to be the primary cause for the thinning of the glaciers.

This study evaluates 35 years (1979 to 2013) of the ERA-Interim reanalysis to identify significant changes in the atmospheric circulation of the Amundsen Sea region. The method of self-organizing maps (SOMs) is used to identify the dominant atmospheric circulation patterns in the region. The SOM methodology allows for identifying specific changes within the more general atmospheric circulation. Sea-level pressure, 10 m winds, and 500 hPa geopotential heights, along with additional secondary fields, are analyzed in this study to identify the significant changes in the atmospheric circulation. Relationships to El Niño-Southern Oscillation (ENSO) and Southern Annular Mode (SAM) climate indices, as well as sea ice extent are investigated to better characterize the atmospheric circulation across the region. Lastly, possible connections between the identified changes in atmospheric circulation and the thinning of the Amundsen Sea embayment glaciers will be presented.