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Interannual variability of Kelvin wave propagation in the wave guides of the equatorial Indian Ocean, the coastal Bay of Bengal and the southeastern Arabian Sea during 1993-2006

DRS at CSIR-National Institute of Oceanography

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Title Interannual variability of Kelvin wave propagation in the wave guides of the equatorial Indian Ocean, the coastal Bay of Bengal and the southeastern Arabian Sea during 1993-2006
 
Creator Rao, R.R.
GirishKumar, M.S.
Ravichandran, M.
Rao, A.R.
Gopalakrishna, V.V.
Pankajakshan, T.
 
Subject Kelvin wave
Indian Ocean
coastal wave
upwelling
 
Description The observed variability of the Kelvin waves and their propagation in the equatorial wave guide of the Indian Ocean and in the coastal wave guides of the Bay of Bengal (BoB) and the southeastern Arabian Sea (AS) on seasonal to interannual time scales during years 1993-2006 is examined utilizing all the available satellite and in-situ measurements. The Kelvin wave regime inferred from the satellite-derived sea surface height anomalies (SSHA) shows a distinct annual cycle composed of two pairs of alternate upwelling (first one occurring during January-March and the second one occurring during August-September) and downwelling (first one occurring during April-June and the second one occurring during October-December) Kelvin waves that propagate eastward along the equator and hit the Sumatra coast and bifurcate. The northern branches propagate counterclockwise over varied distances along the coastal wave guide of the BoB. The potential mechanisms that contribute to the mid-way termination of the first upwelling and the first down welling Kelvin waves in the waveguide of the BoB are hypothesized. The second downwelling Kelvin wave alone reaches the southeastern AS, and it shows large interannual variability caused primarily by similar variability in the equatorial westerly winds during boreal fall. The westward propagating downwelling Rossby waves triggered by the second downwelling Kelvin wave off the eastern rim of the BoB also shows large interannual variability in the near surface thermal structure derived from SODA analysis. The strength of the equatorial westerlies driven by the east-west gradient of the heat sources in the troposphere appears to be a critical factor in determining the observed interannual variability of the second downwelling Kelvin wave in the wave guides of the equatorial Indian Ocean, the coastal BoB, and the southeastern AS
 
Date 2009-12-24T05:03:51Z
2009-12-24T05:03:51Z
2010
 
Type Journal Article
 
Identifier Deep-Sea Research I, vol.57; 1-13
no
http://drs.nio.org/drs/handle/2264/3523
 
Language en
 
Rights An edited version of this paper was published by Elsevier. Copyright [2009] Elsevier
 
Publisher Elsevier