Association between Antarctic Sea ice, Pacific SST and the Indian summer monsoon: An observational study

Abstract

In this paper, results of diagnostic analysis for the period 1983–2015, demonstrate a robust relationship between Indian Summer Monsoon Rainfall (ISMR) and sea ice area (SIA) over the two sectors of Antarctica namely, Western Pacific Ocean (WPO) and Bellingshausen and Amundsen Seas (BAS). A significant direct (inverse) relationship is observed between ISMR and SIA over the WPO (BAS) sector. Further, plausible physical mechanism governing this relationship is proposed. El Niño Modoki exhibit direct (inverse) relation with SIA over BAS (WPO) sector during summer monsoon season, which has prompted investigation of SIA-El Niño Modoki-ISMR connection. The linkage between southern polar sea ice and the Indian summer monsoon has been demonstrated through the Pacific Ocean, wherein above normal SIA over the BAS (WPO) sector is associated with concurrent warm equatorial central (western) Pacific Sea Surface Temperature (SST) anomalies. Associated meridional circulations supplemented by above normal BAS (WPO) SIA extremes is accompanied by an ascending motion over the equatorial central (western) Pacific. In turn, through large-scale zonal circulation, ascending branch of circulation over the central (western) Pacific Ocean contemporaneously impacts ISMR adversely (favourably). Large-scale atmospheric circulation modulated by equatorial Pacific SST signature is suggested as a possible link between Antarctic sea ice and ISMR.