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A common spatial mode for intra-seasonal and inter-annual variation and predictability of the Indian summer monsoon

Mohan, Ajaya RS and Goswami, BN (2000) A common spatial mode for intra-seasonal and inter-annual variation and predictability of the Indian summer monsoon. In: Current Science, 79 (8). pp. 1106-1111.

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Abstract

How and to what extent the intra-seasonal oscillations (ISOs) of the Indian summer monsoon influence the seasonal mean and its inter-annual variability is investigated using long records of daily circulation data (1956-1997) and outgoing long wave radiation (OLR) data (1974-1997), The underlying spatial structure of a typical. ISO cycle that is invariant from event to event and year to year is brought out. It is shown that the intra-seasonal and interannual variations are governed by a common mode of spatial variability. A higher frequency of occurrence of active (break) conditions within a monsoon season, therefore, could result in a strong (weak) summer monsoon. Two-dimensional probability density function estimates of the ISOs show that strong (weak) monsoon years are indeed associated with higher probability of occurrence of active (break) conditions. For the first time, these results show that the frequency of chaotic ISO regimes determine the seasonal mean monsoon, thereby setting a limit on monsoon predictability.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Indian Academy of Sciences.
Department/Centre: Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 04 Oct 2004
Last Modified: 19 Sep 2010 04:15
URI: http://eprints.iisc.ernet.in/id/eprint/1674

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