A dipole mode in the tropical Indian Ocean

Saji, NH and Goswami, BN and Vinayachandran, PN and Yamagata, T (1999) A dipole mode in the tropical Indian Ocean. In: Nature, 401 (6751). pp. 360-363.

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Abstract

For the tropical Pacific and Atlantic oceans, internal modes of variability that lead to climatic oscillations have been recognized(1,2), but in the Indian Ocean region a similar ocean-atmosphere interaction causing interannual climate variability has not yet been found(3). Here we report an analysis of observational data over the past 40 years, showing a dipole mode in the Indian Ocean: a pattern of internal variability with anomalously low sea surface temperatures off Sumatra and high sea surface temperatures in the western Indian Ocean, with accompanying wind and precipitation anomalies. The spatio-temporal links between sea surface temperatures and winds reveal a strong coupling through the precipitation field and ocean dynamics. This air-sea interaction process is unique and inherent in the Indian Ocean, and is shown to be independent of the El Nino/Southern Oscillation. The discovery of this dipole mode that accounts for about 12% of the sea surface temperature variability in the Indian Ocean-and, in its active years, also causes severe rainfall in eastern Africa and droughts in Indonesia-brightens the prospects for a long-term forecast of rainfall anomalies in the affected countries.

Item Type:	Journal Article
Publication:	Nature
Publisher:	Macmillan Magazines Ltd.
Additional Information:	Copyright of this article belongs to Macmillan Magazines Ltd.
Department/Centre:	Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited:	20 Mar 2009 06:35
Last Modified:	19 Sep 2010 04:58
URI:	http://eprints.iisc.ac.in/id/eprint/17757

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