A search for ENSO teleconnections in the west Antarctic Peninsula climate in austral winter

Abstract

Evidence is sought for El Niño–Southern Oscillation (ENSO) teleconnections in the South Pacific extratropical atmospheric circulation and in seasonal temperatures in the west Antarctic Peninsula (WAP) during austral winter. Emphasis is placed on winter sea surface temperature (SST) changes in the tropical central Pacific to infer the seasonal evolution of ENSO events. SST changes are statistically independent of absolute SSTs and are also rarely the same in warm events. Variations in winter tropical SST changes are also found to be strongly mirrored in South Pacific extratropical circulation adjustments that are consistent with Rossby wave modulation. They include changes in the westerlies in the central Pacific (40°S–55°S) and in Antarctic Peninsula meridional flows. ENSO teleconnections are found to indirectly reach WAP winter temperatures via alterations in the local ice extent that is sensitive to the local, ENSO teleconnected, meridional circulation variations. Winter temperatures are also very closely coupled to the winter ‘baseline’ ice extent. It is shown that above-normal pre-winter ice extent is a necessary condition for cold winters but that wintertime ice extent changes owing to ENSO-related meridional flow variations must also be taken into account. The study results are supported by a regression modelling analysis that captures most cold winters in the study period. From these findings and those of previous ENSO teleconnection studies for the South Pacific, it is surmised that ENSO plays a major role in driving interannual temperature variability in this part of Antarctica in the austral winter. Copyright © 2000 Royal Meteorological Society