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Indian Ocean-monsoon coupled interactions and impending monsoon droughts

journal contribution
posted on 2023-05-16, 19:37 authored by Krishnan, R, Ramesh, KV, Samala, BK, Meyers, GA, Slingo, JM, Fennessy, MJ
Monsoon droughts over the Indian subcontinent emanate from failures in the seasonal (June-September) monsoon rains. While prolonged dry-spells ("monsoonbreaks") pervade on sub-seasonal/intra-seasonal time-scales, the underlying causes for these long-lasting anomalies remain elusive. Based on analyses of a suite of observed data sets, we report an ocean-atmosphere dynamical coupling on intra-seasonal time-scales, in the tropical Indian Ocean, which is pivotal in forcing extended monsoon-breaks and causing droughts over the subcontinent. This coupling involves a feedback between the monsoonal flow and thermocline depth in the Equatorial Eastern Indian Ocean (EEIO), in which an anomaly of the summer monsoon circulation induces downwelling and maintains a higher-than-normal heat-content. The near-equatorial anomalies induce strong and sustained suppression of monsoon rainfall over the subcontinent. It is concluded that the intraseasonal evolution of the ocean-monsoon coupled system is a vital key to unlocking the dynamics of monsoon droughts. Copyright 2006 by the American Geophysical Union.

History

Publication title

Geophysical Research Letters

Volume

33

Issue

8

Pagination

L08711

ISSN

0094-8276

Department/School

Institute for Marine and Antarctic Studies

Publisher

American Geophysical Union

Place of publication

United States

Repository Status

  • Restricted

Socio-economic Objectives

Social impacts of climate change and variability

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