West India Coastal Current and Lakshadweep High/Low

The West India Coastal Current (WICC) flows northward during November-Febru ary and southward during April-September. At the time of formation of the n orthward (southward) phase of the current, a high (low) in sea level - the Lakshadweep High (Low), forms off southwestern India, and migrates westward across the Arabian Sea. The annual cycle of the WICC and that of the Laksh adweep High/Low arise from a set of circumstances that are special to the N orth Indian Ocean. This relatively small tropical basin is driven by season al monsoon winds, As a result, its wind-driven near-surface circulation con sists primarily of annual and semi-annual long, equatorially-trapped Kelvin and Rossby waves, and coastally-trapped Kelvin waves. In terms of these wa ves, the West India Coastal Current is a superposition of annual and semian nual coastally-trapped Kelvin waves. The Lakshadweep High/Low forms when th e Kelvin waves, on turning around Sri Lanka, and propagating northward alon g the west coast of India, radiate Rossby waves.