Indian Monsoon Variability and Predictability

K. Krishna Kumar
CIRES Visiting Fellow

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Interannual variability and predictability, two very important aspects, of the Indian Monsoon will be addressed. Though the former is well known to be ENSO driven, we show that the convectional wisdom of El Niño (warm-ENSO) events leading to monolithic monsoon failures is not always true and offer some plausible explanations for such a paradox and provide observational and dynamical (through idealized General Circulation Model, GCM experiments) evidence. Predictability of the Indian monsoon rainfall on seasonal time scales is assessed in a suite of atmospheric GCM (AGCM) simulations forced with observed global sea surface temperatures (SSTs). We find the skill in predicting Indian monsoon in AGCMs is woefully poor. Our analysis of the reasons for failure exposes a flaw in the popular design of dynamical prediction systems. The approach of driving atmospheric models with a projected ocean surface temperature presupposes Indian monsoon variability to be a consequence solely of the atmosphere reacting to the ocean. We demonstrate significant improvements in the skill of Indian monsoon predictions when atmospheric models are coupled to, and fully interactive with the ocean, with coupling over the tropical warm pool being critical.

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10 November, 2004
2 PM/ DSRC 1D 403
Refreshments at 1:50
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