Evidence for Eddy Formation in the Eastern Arabian Sea During the Northeast Monsoon
NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
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The seasonal formation of a large 500-800 km diameter anticyclonic eddy in the upper 300-400 m of the Eastern Arabian Sea during the northeast monsoon period December-April is indicated from hydrographic and satellite altimetry sea level observations, as well as from numerical model experiments. The center of the eddy circulation is approximately 10 degrees N, 70 degrees E, just to the west fo the north-south Laccadive Island chain. In this paper the eddy is called the Laccadive High LH. In some ways it is like a mirrorlike counterpart to the Great Whirl, which develops during the southwest monsoon off the Somali coast western Arabian Sea. The LH occurs at the same latitude but on opposite side of the basin during the reversed monsoon. It is different from the Great Whirl, however, in its formation process, it intensity, and its decay. The hydrographic data obtained from surveys all during a single season give sufficiently close station spacing allow reasonable contouring of the geopotential surfaces and of the properties within and around the LH region with minimum time aliasing. The Geosat altimeter record extends over 4 years, during which the seasonal variability of the LH indicates a dynamic relief of approximately 15-20 cm, which is in good agreement with the hydrographic observations. The altimetry time series also suggests a westward translation of the OH by January with a subsequent dissipation in midbasin.
- Physical and Dynamic Oceanography