Summary of Abstract Submission

Abstract Submission No. IO50-08-0030PresentationPoster

INTER-SEASONAL AND INTER-ANNUAL VARIABILITY OF THE SEYCHELLES CHAGOS THERMOCLINE RIDGE

RACHEAL CHACKO*1, N. ANILKUMAR1, JENSON V. GEORGE2, P. SABU1

1 NATIONAL CENTRE FOR ANTARCTIC AND OCEAN RESEARCH, INDIA
2 NATIONAL INSTITUTE OF OCEAN TECHNOLOGY, INDIA

ABSTRACT :

The Seychelles Chagos Thermocline ridge (SCTR) in the southwestern tropical Indian Ocean is a region of year round upwelling. Lying between 5S and 10S and 50-80E, this region is bound in the south by the South Equatorial Current and in the north, during winter, by the Equatorial Counter Current and the equatorial jets during the monsoon transition. Studies have shown that sea surface temperature (SST) variability in the SCTR region can modulate cyclonic activity as well as induces above-average rainfall along Indian sub-continent during the following monsoon. In the present study observations along a longitudinal section (65E) extending from 10N to 18S during two boreal winters (November 2008, 2009) and one boreal summer (June 2009) has been used. There is a significant change in the thermocline structure during these periods. The shallow thermocline in this region shows inter-seasonal variation with the boreal winter to be more active than the boreal summer. Also during November 2008 the thermocline ridge variability is more pronounced than November 2009 which shows that both inter-seasonal and interannual variability is prevalent in this region. The variability in the wind stress curl associated with the change in wind pattern could be a reason for this. In conjunction with the thermocline modulations, the watermass structure in the north and south of the SCTR show a significant seasonal variability. The Arabian Sea High Saline Waters shows large southward intrusion during the boreal winters. The boreal summer show the presence of low saline waters south of the SCTR whose presence