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The evolution of Indian summer monsoon in 1997 and 1983

Srinivasan, J and Nanjundiah, Ravi S (2002) The evolution of Indian summer monsoon in 1997 and 1983. In: Meteorology and Atmospheric Physics, 79 (3&4). pp. 243-257.

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Abstract

During most El-Nino events the Indian summer monsoon rainfall has been below normal. El-Nino that occurred during 1997 was one of the strongest in the 20th century, but did not have an adverse impact on the Indian summer monsoon rainfall in 1997. This is despite the fact that most parameters observed in May 1997 suggested that the Indian summer monsoon rainfall may be below normal. This intriguing feature of the 1997 Indian summer monsoon rainfall has been examined by studying the evolution of various parameters from May to August. The behavior of the 1997 monsoon is related to its evolution during June and July, with westward migration of cloudbands from West Pacific that increased convection over Bay of Bengal. We find that there exists a significant correlation between convective activity over Bay of Bengal and winds over the Arabian Sea with the latter lagging convection over Bay of Bengal by about three days. The convective activity over Bay of Bengal induces stronger winds over the Arabian Sea and this in turn enhances advection of moisture into the Indian landmass and leads to increased precipitable water and strength of the monsoon. Using a simple thermodynamic model we show that increased precipitable water during July leads to increased rainfall. A similar behavior has also been noticed during the 1983 monsoon. with precursors indicating a possible poor monsoon but subsequent events changed the course of the monsoon.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Springer Verlag Wien.
Department/Centre: Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 15 Sep 2004
Last Modified: 19 Sep 2010 04:16
URI: http://eprints.iisc.ernet.in/id/eprint/2013

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