84th AMS Annual Meeting

Wednesday, 14 January 2004
Indian Ocean response to atmospheric intraseasonal oscillations
Hall 4AB
Galina Chirokova, University of Colorado, Boulder, CO; and P. J. Webster
The interaction between the interannual and intraseasonal variability of the Indian Ocean has been recently discussed by a number of authors. We investigate the Indian Ocean response to a composite atmospheric intraseasonal oscillation (ISO) event. The composite 41 days forcing is based on the days of the precipitation maximum at the equator. A 4 and 1/2 layers Indian Ocean model is used to investigate the oceanic response. Results show that the ocean warms before the precipitation reaches maximum at the equator and cools after that. These changes in the SST are about 0.1-0.2 degrees C, and are accompanied by changes in the mixed layer depth and thermocline depth on the order of several meters. The meridional oceanic heat transport changes by 1.5 PW during the composite event. The signal in the ocean is propagated via a set of equatorial waves. The detailed oceanic response is investigated, and the possible consequences for the oceanic feedback and influence on monsoon active and break periods are discussed.

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