Signatures of Indian Ocean dipole and El Nino-Southern Oscillation events in sea level variations in the Bay of Bengal

Show simple item record Aparna, S.G. McCreary, J.P. Shankar, D. Vinayachandran, P.N. 2012-12-05T06:11:54Z 2012-12-05T06:11:54Z 2012
dc.identifier.citation Journal of Geophysical Research, vol.117; 2012; C10012, 13pp.; doi:10.1029/2012JC008055
dc.description.abstract We investigate the impact of the Indian Ocean Dipole (IOD) and El Nino and the Southern Oscillation (ENSO) on sea level variations in the North Indian Ocean during 1957-2008. Using tide-gauge and altimeter data, we show that IOD and ENSO leave characteristic signatures in the sea level anomalies (SLAs) in the Bay of Bengal. During a positive IOD event, negative SLAs are observed during April-December, with the SLAs decreasing continuously to a peak during September-November. During El Nino, negative SLAs are observed twice (April-December and November-July), with a relaxation between the two peaks. SLA signatures during negative IOD and La Nina events are much weaker. We use a linear, continuously stratified model of the Indian Ocean to simulate their sea level patterns of IOD and ENSO events. We then separate solutions into parts that correspond to specific processes: coastal alongshore winds, remote forcing from the equator via reflected Rossby waves, and direct forcing by interior winds within the bay. During pure IOD events, the SLAs are forced both from the equator and by direct wind forcing. During ENSO events, they are primarily equatorially forced, with only a minor contribution from direct wind forcing. Using a lead/lag covariance analysis between the Nino-3.4 SST index and Indian Ocean wind stress, we derive a composite wind field for a typical El Nino event: the resulting solution has two negative SLA peaks. The IOD and ENSO signatures are not evident off the west coast of India.
dc.language.iso en
dc.publisher American Geophysical Union
dc.rights n edited version of this paper was published by AGU. Copyright [2012] AGU. To view the published open abstract, go to
dc.subject southern oscillation
dc.subject el nino phenomena
dc.subject sea level variations
dc.title Signatures of Indian Ocean dipole and El Nino-Southern Oscillation events in sea level variations in the Bay of Bengal
dc.type Journal Article

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