Surface currents in the equatorial Indian Ocean during spring and fall - An altimetry based analysis

Abstract

This communication presents the results of a study aimed at investigating the nature and variability of surface currents in the equatorial Indian Ocean between 5 degrees N and 5 degrees S during spring and fall seasons. Geostrophic surface currents were computed using 1 degrees x 1 degrees gridded sea surface height (SSH) anomalies derived from TOPEX-POSEIDON (T/P) altimeter data over the years, 1993 to 2000. The results show that the spring Wyrtki jet derived between April and June is restricted to just south of the equator, whereas, the fall jet derived between October and December is almost symmetrical about the equator. These jets are found to be about 400 km wide with a speed of 70-80 cm/sec. Maximum duration of these wind-driven, eastward flows is about three months in both the seasons. The tendency of these jets to be either weak or totally absent during 1997-98 is attributed to the strong ENSO-IOD event of 1997.