Multi-Temporal Influences of Large-Scale Atmospheric Patterns On Antarctic Coastal Polynyas

Abstract. During the austral ice advance season, sea ice expands across the Southern Ocean, significantly reducing gas, heat, and moisture transfer between the atmosphere and ocean. Situated along the Antarctica coastline are areas of open water, minimal sea ice concentration, or relatively thin ice – called coastal polynyas. Coastal polynyas continuously reconnect the atmosphere and ocean. Antarctic coastal polynyas’ greatest geographic influence occurs through their contribution to deep water formation and the global Thermohaline Circulation. Coastal polynya impacts are partially controlled by their size. Larger polynyas allow greater rates of sea ice production, bottom water formation, and total biological productivity. This study examines the role that large-scale atmospheric patterns play in Antarctic coastal polynya size variability. The Southern Annular Mode (SAM), El Niño-Southern Oscillation (ENSO), and the Amundsen Sea Low (ASL) together significantly influence the sizes of 20 of the 25 Antarctic coastal polynyas in this study. The SAM exerts its strongest influence in East Antarctica, where a +SAM stunts coastal polynya growth. ENSO, a tropical phenomenon with significant West Antarctica teleconnections, promotes polynya growth during La Niña. The ASL, an exclusively West Antarctica phenomenon, enhances polynya growth in the Amundsen and Bellingshausen Seas as it intensifies and as it migrates northeast. In contrast, an eastward migration of the ASL suppresses polynya expansion in the Weddell Sea. Variability in the SAM and in the ASL’s intensity and latitudinal location impact monthly and seasonal polynya size variability. Variability in ENSO and in the ASL’s intensity and longitudinal location impact annual, seasonal, and monthly polynya size variability, respectively.