Amplification of the ENSO Effects on Indian Summer Monsoon Rainfall by Absorbing Aerosols

Thursday, 18 December 2014
Maeng-Ki Kim1, William K-M Lau2, Kyu-Myong Kim2, Jeong Sang1, Yeon-Hee Kim3 and Woo-Seop Lee4, (1)Kongju National University, Gongju, South Korea, (2)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (3)POSTEC, Pohang, South Korea, (4)APCC, Busan, South Korea
In this study, we present observational evidence of the elevated heat pump (EHP) effect due to absorbing aerosols on Indian summer monsoon rainfall based on a composite analysis of satellite measurements and MERRA reanalysis data for the period 1979-2011. Modulation of the ENSO effect on Indian summer monsoon rainfall by the EHP effect was also explored. In the pre-monsoon season (April to May), rainfall during a La Nina phase is reduced over the expansive desert region from western Asia, including the Middle East, to northern India and thereby the La Nina effect provides abundant aerosols that are necessary to work the EHP effect in the northern India. Thus, the EHP effect due to abundant absorbing aerosols during a La Nina phase is strongly associated with atmospheric warming, increased moisture transport from the Indian Ocean to the Bay of Bengal, and enhanced pre-monsoon (May-June) rainfall over northern India. This finding suggests that the EHP effect plays an important role in amplifying the La Nina effect on Indian summer monsoon.