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Role of land-ocean contrast in the indian summer monsoon rainfall

Gadgil, S and Francis, PA and Rajendran, K and Nanjundiah, RS and Rao, SA (2021) Role of land-ocean contrast in the indian summer monsoon rainfall. [Book Chapter]

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Official URL: https://doi.org/10.1142/9789811216602_0001


For well over 300 hundred years, the monsoon has been considered to be a gigantic land-sea breeze driven by the land-ocean contrast in surface temperature. This popular perception of the monsoon as a gigantic land-sea breeze is not only mentioned in text books and reviews but also used in some studies of the impact of global warming to deduce the expected monsoon variability from the expected land-ocean contrast. If the primary cause of the monsoon is the differential heating between land and ocean, we expect enhanced land-sea contrast to be associated with enhanced monsoon rainfall. It is important to assess whether observations of monsoon variability are consistent with this expectation. Since models are used for deriving the nature of the impact of a change in land-ocean contrast on the monsoon, it is also important to investigate if such a role of land-ocean contrast is simulated by models. Here, we address this problem with an analysis of the relationship between the Indian summer monsoon rainfall (ISMR) and the surface temperature of the land, the surrounding ocean, and the land-ocean contrast in observations and simulations using one high-resolution atmospheric model and one coupled model. We find that in all three cases, the ISMR is negatively correlated with the land surface temperature as well as land-ocean contrast. Thus, for observations and models, the relationship of the variation of land-ocean contrast with that of the monsoon rainfall is opposite to what is expected from the land-sea breeze hypothesis. This clearly suggests that the time has come to abandon the perception of the monsoon system as a gigantic land-sea breeze. © 2021 by World Scientific Publishing Co. Pte. Ltd.

Item Type: Book Chapter
Publication: Multiscale Global Monsoon System, The
Series.: World Scientific Series on Asia-Pacific Weather and Climate
Publisher: World Scientific Publishing Co.
Additional Information: The copyright for this article belongs to Authors
Department/Centre: Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 02 Sep 2021 11:37
Last Modified: 02 Sep 2021 11:37
URI: http://eprints.iisc.ac.in/id/eprint/69617

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