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Theoretical aspects of the onset of Indian summer monsoon from perturbed orography simulations in a GCM

Chakraborty, A and Nanjundiah, RS and Srinivasan, J (2006) Theoretical aspects of the onset of Indian summer monsoon from perturbed orography simulations in a GCM. In: Annales Geophysicae, 24 (8). pp. 2075-2089.

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Abstract

A theory is proposed to determine the onset of the Indian Summer Monsoon (ISM) in an Atmospheric General Circulation Model (AGCM). The onset of ISM is delayed substantially in the absence of global orography. The impact of orography over different parts of the Earth on the onset of ISM has also been investigated using five additional perturbed simulations. The large difference in the date of onset of ISM in these simulations has been explained by a new theory based on the Surface Moist Static Energy (SMSE) and vertical velocity at the mid-troposphere. It is found that onset occurs only after SMSE crosses a threshold value and the large-scale vertical motion in the middle troposphere becomes upward. This study shows that both dynamics and thermodynamics play profound roles in the onset of the monsoon.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Annales Geophysicae.
Keywords: Meteorology and atmospheric dynamics (Generalcirculation; Precipitation;Tropical meterology)
Department/Centre: Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 28 Jun 2007
Last Modified: 17 Jan 2012 09:17
URI: http://eprints.iisc.ernet.in/id/eprint/11300

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