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Mechanisms of variability and predictability of the tropical coupled ocean-atmosphere system

Goswami, BN and Selvarajan, Sudha and Krishnamurthy, V (1993) Mechanisms of variability and predictability of the tropical coupled ocean-atmosphere system. In: Proceedings of the Indian Academy of Sciences - Earth & Planetary Sciences, 102 (1). pp. 49-72.

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Abstract

A conceptual model is proposed to explain the observed aperiodicity in the short term climate fluctuations of the tropical coupled ocean-atmosphere system. This is based on the evidence presented here that the tropical coupled ocean-atmosphere system sustains a low frequency inter-annual mode and a host of higher frequency intra-seasonal unstable modes. At long wavelengths, the low frequency mode is dominant while at short wavelengths, the high frequency modes are dominant resulting in the co-existence of a long wave low frequency mode with some short wave intra-seasonal modes in the tropical coupled system. It is argued that due to its long wavelength, the low frequency mode would behave like a linear oscillator while the higher frequency short wave modes would be nonlinear. The conceptual model envisages that an interaction between the low frequency linear oscillator and the high frequency nonlinear oscillations results in the observed aperiodicity of the tropical coupled system. This is illustrated by representing the higher frequency intra-seasonal oscillations by a nonlinear low order model which is then coupled to a linear oscillator with a periodicity of four years. The physical mechanism resulting in the aperiodicity in the low frequency oscillations and implications of these results on the predictability of the coupled system are discussed.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Indian Academy of Sciences.
Keywords: Aperiodicity - inter-annual variability - tropical coupled ocean-atmosphere system;predictability;convergence feedback;multiple periodic attractors;low frequency oscillator;non linear intra-seasonal modes.
Department/Centre: Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 11 Feb 2011 11:53
Last Modified: 11 Feb 2011 11:53
URI: http://eprints.iisc.ernet.in/id/eprint/35538

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