Composite analysis of the surface effects of El Nino southern oscillation teleconnections on Antarctica

Significant work has gone into identifying and understanding upper level height anomaly in the Amundsen and Bellingshausen Sea regions associated with El Niño Southern Oscillation (ENSO) events. This work focuses on the effect teleconnections associated with ENSO have on the Antarctic surface and the adjacent Southern Ocean. Composites of (European Centre for Medium-Range Weather Forecasting Re-analysis 40) ERA-40 data from 1979-2002 of ENSO events, and of (European Centre for Medium-Range Weather Forecasting Re-analysis interim) ERA-Interim from 1989-2010, allow illustration of how these events translate to surface effects, via surface pressure and temperature. Prior work has utilized composite techniques involving direct comparison of the cool phase (La Niña) to the warm phase (El Niño) whereas this work utilizes composites of both the warm phase and the cool phase compared with neutral conditions to determine differences between the signal seen in these phases. To ensure the accuracy of these findings regions with values exceeding the confidence intervals are compared with ground Automatic Weather Stations (AWS) from the University of Wisconsin-Madison that have not been used in the reanalysis. Comparisons between composites of El Niño and La Niña indicate distinct differences in the location and seasonality of the teleconnection. The signal of El Niño is located primarily within the anticipated regions of the Amundsen and Bellingshausen Sea , while the signal from La Niña occurs in this region or East Antarctica depending on seasonality.