Present‐Day Regional Antarctic Sea Ice Response to Extratropical Cyclones

Abstract

Both atmospheric warming and poleward moisture transport increase the likelihood of sea ice surface melt. In the Southern Hemisphere, short‐lived extratropical cyclones (ETCs) are responsible for a bulk of total heat and moisture transport toward high latitudes. Although these storms form ubiquitously in the midlatitudes, moisture availability and temperature characteristics vary by source region. In this study, we assess atmospheric, oceanic, and sea ice concentration (SIC) anomalies associated with austral winter ETCs over different Antarctic regions using ERA5 reanalysis data. Between 1990 and 2019, we find a total of 514 ETCs, with greater storm frequency in the eastern hemisphere groups. Compared to the climatology, sea ice melts (grows) behind the warm (cold) front of each system and is negatively correlated with atmospheric poleward moisture transport, temperature, meridional winds, and sea surface temperature for all ETCs. We find that Bellingshausen storms move moisture and warm air furthest poleward over their lifespan. However, East Weddell and East Antarctic ETCs are responsible for greater absolute poleward moisture transport than Bellingshausen and Ross systems. More intense ETCs correspond to greater SIC through Day 1, suggesting that SIC impacts ETC strength, regardless of ETC region. From cyclogenesis to cyclolysis, sea ice extent declines underneath composite ETCs, trends are generally not significant. Overall, while sea ice response produced by ETC‐induced atmospheric and oceanic changes varies regionally, the long‐term impacts of ETCs on regional sea ice are negligible over the study period.