Show simple item record

dc.contributor.authorShankar, D.
dc.contributor.authorShetye, S.R.
dc.contributor.authorJoseph, P.V.
dc.date.accessioned2007-05-14T07:04:52Z
dc.date.available2007-05-14T07:04:52Z
dc.date.issued2007
dc.identifier.citationJournal of Earth System Science, vol.116(5); 385-406
dc.identifier.urihttp://drs.nio.org/drs/handle/2264/607
dc.description.abstractWe use daily satellite estimates of sea surface temperature (SST) and rainfall during 1998-2005 to show that onset of convection over the central Bay of Bengal (88-92E, 14-18N) during the core summer monsoon (mid-May to September) is linked to the meridional gradient of SST in the bay. The SST gradient was computed between two boxes in the northern (88-92E, 18-22N) and southern (82-88E, 4-8N) bay; the latter is the area of the cold tongue in the bay linked to the Summer Monsoon Current. Convection over central bay followed the SST difference between the northern and southern bay (Delta T) exceeding 0.75 degC in 28 cases. There was no instance of Delta T exceeding this threshold without a burst in convection. There were, however, five instances of convection occurring without this SST gradient. Long rainfall events (events lasting more than a week) were associated with an SST event (Delta T >= 0.75 degC); rainfall events tended to be short when not associated with an SST event. The SST gradient was important for the onset of convection, but not for its persistence: convection often persisted for several days even after the SST gradient weakened. The lag between Delta T exceeding 0.75 degC and the onset of convection was 0-18 days, but the lag histogram peaked at one week. In 75% of the 28 cases, convection occurred within a week of Delta T exceeding the threshold of 0.75 degC. The northern bay SST, T_N, contributed more to Delta T, but it was a weaker criterion for convection than the SST gradient. A sensitivity analysis showed that the corresponding threshold for T_N was 29 degC. We hypothesise that the excess heating (~ 1 degC above the threshold for deep convection) required in the northern bay to trigger convection is because this excess in SST is what is required to establish the critical SST gradient.
dc.description.sponsorshipDepartment of Ocean Development, New Delhi.
dc.format.extent810380 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherIndian Academy of Sciences
dc.rightsIndian Academy of Sciences, Bangalore
dc.subjectSouthwest monsoon
dc.subjectIndian summer monsoon
dc.subjectSea surface temperature gradient
dc.subjectITCZ
dc.subjectSummer Monsoon Current
dc.subjectSouthwest Monsoon Current
dc.subjectTropical Convergence Zone
dc.subjectIndian Ocean
dc.titleLink between convection and meridional gradient of sea surface temperature in the Bay of Bengal
dc.typeJournal Article


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record