Abstract Title: The Influence of Extreme Amundsen Sea Low (ASL) Events on West Antarctica
Abstract Submitted to: CRYOSPHERE SCIENCES
Abstract Text:
West Antarctica’s climate is strongly influenced by different atmospheric circulation features. One of the most prominent is the Amundsen Sea Low (ASL), which is a climatological low-pressure center located in the Pacific sector of the Southern Ocean (SO). The ASL can promote changes in surface winds, surface temperature, sea surface temperature (SST), sea ice concentration (SIC), and the direction and speed of sea ice drift around the continent. While there is a general understanding of the impact of standard ASL events on West Antarctica, little is known about extreme instances of the ASL. As such, this research project uses European Center for Medium-Range Weather Forecast (ECMWF) Reanalysis version 5 (ERA5) data alongside data from the National Snow and Ice Data Center (NSIDC) to study extreme ASL events and their effect on West Antarctica's climate. We use Hosking’s ASL Climate Index to determine the date, location, and intensity of all ASL events from 1979 to 2022. We then produce a time series analysis and select those ASL events with the strongest and weakest intensities based on actual central pressure. From the ERA5 dataset we extract mean sea level pressure, surface winds, surface temperature, and SST associated with extreme occurrences of the ASL; SIC is extracted from NSIDC data. Variables are then examined relative to monthly climatologies to discern the impact of the ASL. Preliminary results suggest that there is a strong latitudinal difference in the central location of extremely strong and weak ASL events, which dictates their impact on West Antarctica’s climate. Large impacts on SIC and temperature are strongly associated with the wind speed and direction around the Low. Additionally, extreme ASL events may be associated not only with the ASL acting alone but also with larger scale components of the atmospheric circulation such as the Southern Annular Mode (SAM), Zonal Wave Three (ZW3), and the El Niño Southern Oscillation (ENSO).
Michelle De Luna
Description
Funded by:
Current Institute of Study/Organization: University of California Los Angeles
Currently Pursuing: Doctorate
Country: US