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Influence of the Atlantic zonal mode on monsoon depressions in the Bay of Bengal during boreal summer

Pottapinjara, V and Girishkumar, MS and Ravichandran, M and Murtugudde, R (2014) Influence of the Atlantic zonal mode on monsoon depressions in the Bay of Bengal during boreal summer. Journal of Geophysical Research D: Atmospheres, 119 (11). pp. 6456-6469.

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Abstract

The influence of the Atlantic Zonal Mode (AZM) or the Atlantic Niño on monsoon depressions in the Bay of Bengal during the boreal summer (June-August) is studied. Our analysis shows that there is a statistically significant difference in the number of monsoon depressions in the Bay of Bengal between the warm and cold phases of the AZM; more (fewer) monsoon depressions form during the cold (warm) phase of AZM. It also shows that there are differences in spatial pattern of trajectories of monsoon depressions; during the cold phase of AZM, the tracks are relatively long and seem to cluster along the axis of core monsoon region compared to the warm phase of AZM. The analysis indicates an increase (a reduction) in low-level cyclonic vorticity and midtropospheric humidity but a reduction (an increase) in vertical wind shear due to anomalous circulation pattern. All of these changes are favorable for the enhancement (suppression) of monsoon depressions during the cold (warm) phase of the AZM. Our analysis further shows a teleconnection pathway by which the AZM can influence the remote Indian Ocean. This could have implications for enhancing monsoon prediction skill, especially during non-El Niño-Southern Oscillation years. Key Points Influence of the AZM on monsoon depressions during boreal summer Cold (warm) AZM increases (decreases) number of monsoon depressions The difference in large-scale atmospheric conditions in the BoB during AZM

Item Type: Article
Additional Information: Copyrights of this article belongs to American Geophysical Union.
Subjects: Oceanography > oceanography
Depositing User: INCOIS Library
Date Deposited: 17 Jul 2014 07:25
Last Modified: 17 Jul 2014 07:25
URI: http://moeseprints.incois.gov.in/id/eprint/610

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