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

Ajaya Ravindran, B. N. Goswami

    Research output: Contribution to journalArticle

    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.

    Original languageEnglish (US)
    Pages (from-to)1106-1111
    Number of pages6
    JournalCurrent Science
    Volume79
    Issue number8
    StatePublished - Oct 25 2000

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    annual variation
    monsoon
    summer
    oscillation
    longwave radiation
    probability density function
    seasonal variation

    ASJC Scopus subject areas

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    A common spatial mode for intra-seasonal and inter-annual variation and predictability of the Indian summer monsoon. / Ravindran, Ajaya; Goswami, B. N.

    In: Current Science, Vol. 79, No. 8, 25.10.2000, p. 1106-1111.

    Research output: Contribution to journalArticle

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