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Mechanisms of low frequency intraseasonal oscillations of the Indian summer monsoon

Krishnan, R and Venkatesan, C (1997) Mechanisms of low frequency intraseasonal oscillations of the Indian summer monsoon. Meteorology and Atmospheric Physics, 62 (1-2). pp. 101-128.

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This work deals with idealized modelling experiments designed to understand the dynamical evolution of low frequency intraseasonal monsoonal oscillations that result from interactions between the large scale monsoon Reverse Hadley Cell (RHC) and moist convective processes. The monsoon differential heating, which primarily determines the low-level convergence of the large-scale monsoon flow, is found to play a decisive role in affecting the northward progression of the monsoonal modes. A strong north-south differential heating leads to a robust generation and steady maintenance of northward propagating monsoonal oscillations. A weaker land-ocean thermal contrast leads to feeble low frequency monsoonal modes that have relatively longer periods in the 30–50 day band. This increase in the period of the monsoonal oscillations due to weak north-south thermal contrast is in good agreement with the observational findings of Yasunari (1980) and Kasture and Keshavamurty (1987). It is speculated that such an increase in the oscillatory period may be an outcome from an elongation in the meridional scale of the transient Hadley type cells which act as resonating cavities for the monsoonal modes

Item Type: Article
Additional Information: Copyright of this article belongs to Springer
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 28 Feb 2015 04:19
Last Modified: 28 Feb 2015 04:19

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