Response of the Atmosphere to Sea Surface Temperature Anomalies over the Equatorial Pacific and the Teleconnections of the Southern Oscillation

Abstract

Abstract In order to improve our understanding of the role of equatorial Pacific sea surface temperature (SST) anomalies in the Southern Oscillation and the variability of the Walker Circulation, we have conducted sensitivity studies with warm SSTA's over different parts of the equatorial Pacific using a general circulation model of GFDL. The model response is compared with the variability of the 15-year control run and the statistical significance of the response is assessed. The anomalies produce dominant changes in the vertical circulation in the equatorial longitude-height plane. Besides the large local increase of precipitation near the anomalies and a slight reduction to the west, there are also global-scale anomalies in the equatorial zonal winds (notably in the upper troposphere) and in tropical sea level pressure. The Pacific Walker Circulation is significantly altered. In the case of eastern and central Pacific anomalies these features resemble the observed circulation anomalies during the low i...