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Droughts of the Indian summer monsoon: Role of clouds over the Indian Ocean

Gadgil, S and Vinayachandran, PN and Francis, PA (2003) Droughts of the Indian summer monsoon: Role of clouds over the Indian Ocean. In: Current Science, 85 (12). pp. 1713-1719.

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Comparison of the evolution of the normal summer monsoon of 2003 with the unanticipated drought of 2002 led to this investigation of the role of the deep convection in the atmosphere (deep cloud systems) over the equatorial Indian Ocean. We find that the link of the Indian monsoon to events over the equatorial Indian Ocean is as important as the well-known link to the dramatic events over the Pacific (El Nino Southern Oscillation; ENSO). Over the equatorial Indian Ocean, enhancement of deep convection in the atmosphere over the western part is generally associated with suppression over the eastern part and vice versa. We call the oscillation between these two states, which is reflected in the pressure gradients and the wind along the equator, the Equatorial Indian Ocean Oscillation (EQUINOO). We show that every season with excess rainfall/drought during 1979-2002 can be 'explained' in terms of favourable/unfavourable phase of either this oscillation or the ENSO or both. In particular, in the monsoon season of 2002 while the ENSO phase was unfavourable but weak, the phase of the EQUINOO was highly unfavourable and a large deficit occurred in the monsoon rainfall.

Item Type: Journal Article
Publication: Current Science
Publisher: Indian Academy Of Sciences
Additional Information: Copyright of this article belongs ton Indian Academy Of Sciences.
Department/Centre: Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 01 Jun 2009 07:05
Last Modified: 19 Sep 2010 04:53
URI: http://eprints.iisc.ac.in/id/eprint/16815

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