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

Maeng-Ki Kim1, William K-M Lau2, Kim Kyu-Myong2, Jeong Sang3, Yeon-Hee Kim4 and Woo-Seop Lee5, (1)Kongju National University, Department of Atmospheric Science, Gongju, South Korea, (2)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (3)Kongju National University, Atmospheric Science, Gongju, Korea, Republic of (South), (4)Pohang University of Science and Technology, Pohang, South Korea, (5)APCC, Busan, Korea, Republic of (South)
Abstract:
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.
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