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Title: Changing Relationship between the Tropical Easterly Jet and the Indian summer Monsoon Rainfall: Role of Indian Ocean Warming
Authors: Rao, D. Nagarjuna
George, Gibies
Sabeerali, C. T.
Ramu, D.A.
Rao, Suryachandra. A.
Keywords: TEJ;ISMR;Indian Ocean Warming;Climate Variability
Issue Date: Nov-2015
Publisher: NISCAIR-CSIR, India
Abstract: Using long-term observational and reanalysis products, we noticed that the strength of the Tropical Easterly Jet (TEJ) stream shows a weakening trend. Model sensitivity experiments with Atmospheric General Circulation Model (ECHAM5-AGCM) hypothesize that the weakening of the TEJ is mainly a result of the recent Indian Ocean warming and the associated with changes in the convection and circulation. Another notable feature is the weakening of the relationship between the TEJ strength and Indian summer monsoon rainfall (ISMR) in recent decades and sensitivity experiments with AGCM confirm the role of the recent Indian Ocean warming in weakening this relationship. Time series of both TEJ strength and ISMR shows a decreasing trend in recent decades. However, the rate of decrease in ISMR is less compared to the decrease in TEJ strength. This seems to be because of the increases in extreme rainfall events over the Indian landmass in recent decades which can compensate the decrease in total rainfall. It suggests that the local convective rainfall events become more frequent and hence, rainfall due to large scale circulation should decrease to maintain the decreasing trend of total rainfall over Indian landmass. In short, our results indicate that the unequal rate of decrease in the ISMR and the TEJ strength in the context of the recent Indian Ocean warming breaks up the relationship between the ISMR and TEJ.
Page(s): 1678-1683
ISSN: 0975-1033 (Online); 0379-5136 (Print)
Appears in Collections:IJMS Vol.44(11) [November 2015]

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