Summer 2015 Extremes over South Asia within the Historical Perspective

Abstract:

South Asian summer in 2015 has been marked by weather events of extremely different nature, including hot extremes over India and Pakistan, and wet extremes over northern, western and eastern states of India. Interestingly, these extremes are happening against the backdrop of warm sea surface temperature anomalies in the equatorial Pacific, which has historically reduced the strength of summer monsoon over South Asia. Given the occurrence of the contrasting anomalies at large and regional scales, in this study, we analyze 2015 extremes over South Asia within the historical perspective. We study the anomalies in the land, atmospheric and oceanic processes that potentially led to the regional heat waves and wet extremes throughout the summer and their connection to the large-scale anomalies in the monsoon dynamic. Additionally, we analyze historical simulations of the CMIP5 GCMs to investigate the likelihood of these anomalies with respect to the pre-industrial time period. Our analysis suggests evolving changes in the monsoon dynamics over South Asia where the lesser-known regional and local drivers have influence on the historical tele-connections.