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Upper ocean variability in the Bay of Bengal during the tropical cyclones Nargis and Laila

DRS at CSIR-National Institute of Oceanography

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Title Upper ocean variability in the Bay of Bengal during the tropical cyclones Nargis and Laila
 
Creator Maneesha, K.
Murty, V.S.N.
Ravichandran, M.
Lee, T.
Yu, W.
McPhaden, M.J.
 
Subject upper ocean
variability
tropical depressions
surface temperature
 
Description Upper ocean variability at different stages in the evolution of the tropical cyclones Nargis and Laila is evaluated over the Bay of Bengal (BoB) during May 2008 and May 2010 respectively. Nargis initially developed on 24 April 2008; intensified twice on 27-28 April and 1 May, and eventually made landfall at Myanmar on 2 May 2008. Laila developed over the western BoB in May 2010 and moved westward towards the east coast of India. Data from the Argo Profiling floats, the Research Moored Array for African-Asian-Australian Monsoon Analysis and prediction (RAMA), and various satellite products are analyzed to evaluate upper ocean variability due to Nargis and Laila. The analysis reveals pre-conditioning of the central BoB prior to Nargis with warm (more than 30 degrees C) Sea Surface Temperature (SST), low (less than 33 psu) Sea Surface Salinity (SSS) and shallow (less than 30 m) mixed layer depths during March-April 2008. Enhanced ocean response to the right of the storm track due to Nargis includes a large SST drop by approx. 1.76 degrees C, SSS increase up to 0.74 psu, mixed layer deepening of 32 m, shoaling of the 26 degrees C isotherm by 36 m and high net heat loss at the sea surface. During Nargis, strong inertial currents (up to 0.9 ms sup(-1)) were generated to the right of storm track as measured at a RAMA buoy located at 15 degrees N, 90 degrees E, producing strong turbulent mixing that lead to the deepening of mixed layer. This mixing facilitated entrainment of cold waters from as deep as 75 m and, together with net heat loss at sea surface and cyclone-induced subsurface upwelling, contributed to the observed SST cooling in the wake of the storm. A similar upper ocean response occurs during Laila, though it was a significantly weaker storm than Nargis.
 
Date 2012-12-05T06:11:42Z
2012-12-05T06:11:42Z
2012
 
Type Journal Article
 
Identifier Progress in Oceanography, vol.106; 2012; 49-61
http://drs.nio.org/drs/handle/2264/4202
 
Language en
 
Rights An edited version of this paper was published by Elsevier. Copyright [2012] Elsevier
 
Publisher Elsevier