Intriguing Relationship between Antarctic Sea Ice, ENSO, and Indian Summer Monsoon

Robust relationship between Antarctic sea ice and Indian summer monsoon rainfall (ISMR) is demonstrated using microwave satellite data for the period 1983–2015. A direct significant relationship is observed between sea ice over the Western Pacific Ocean (WPO) sector and ISMR, while for the same period, an inverse relationship is observed between sea ice over the Bellingshausen and Amundsen Seas (BAS) sector with that of ISMR. The underlying physical mechanism that relays southern polar variability signal to the Indian summer monsoon region is shown through the Pacific Ocean marked by El Niño Southern Oscillation (ENSO), wherein above normal sea ice over BAS (WPO) sector is associated with concurrently occurring warm sea surface temperature (SST) anomalies over the central (western) equatorial Pacific. Anomalous meridional circulations supplemented by above normal BAS (WPO) sea ice is accompanied by an ascending motion over the central (western) equatorial Pacific, which contemporaneously impacts summer monsoon rainfall over the Indian region adversely (favorably). The connection of ISMR with that of sea ice over BAS and WPO sectors as well as the governing physical mechanism is documented in Prabhu et al. (2021). Physical mechanism for ISMR-sea ice link is speculated through large-scale atmospheric circulations. Antarctic sea ice–ENSO–Walker cell–Hadley cell– ISMR is a new channel proposed in this study. The present study is dedicated at diagnosing regional facets of the relationship between spatial distribution of rainfall over India and sea ice averaged over BAS and WPO sectors during the summer monsoon season and to understand the physical mechanism governing their relation. A two-way interaction between sea ice over Antarctica and SST over the equatorial Pacific is suggested. Further, it is verified that Antarctic sea-ice variability, in conjunction with ENSO, has a significant regionally dependent impact on rainfall variability over different parts of India. This chapter shows trends and tele-connections of Antarctic sea ice with ISMR and ENSO. It elucidates the mechanism for connection between southern polar sea ice and ENSO. The chapter describes physical approach to Antarctic sea ice–ENSO–ISMR link. It discusses regional perspectives of summer monsoon rainfall over India, sea ice, and the ENSO connection. The chapter provides major conclusions and new insights on these tele-connections. Antarctic sea ice fluctuations have an immense capability to i