139736eo.pdf (20MB) - Japan Oceanographic Data Center

PHYSICAL OCEANOGRAPHY OF THE NORTHERNINDIAN OCEAN - A PERSPECTIVEV.V. VARADACHARINational Institute of OceanographyDona Paula, 403 004 GoaIndiaABSTRACTThe northern Indian Ocean, including the Bay of Bengal, the Arabian Sea and the adjacentgulfs, is unique in respect of its physical oceanography and meteorology because of the monsoons.Nowhere else does the Ocean undergo such regular, widespread and large-scale seasonal changesin wind forcing and consequent changes in the characteristics of the ocean, especially thecirculation. The uniqueness of the northern Indian Ocean and the monsoons led to severalinternational expeditions such as IIOE, ISMEX, MONEX etc., which provided basic data on theoceanography and meteorology of the area. In spite of all these expeditions, our knowledge of thearea is still quite meagre.In order to understand the interannual variability of the monsoons and the mechanisms thatdetermine their variability and predictability, several components have been identified in the TOGA(Tropical Ocean and Global Atmosphere) and WOCE (World Ocean Circulation Experiment)programme defined by CCCO (the Joint SCOR-IOC Committee on Climatic Changes and theOcean) for the northern Indian Ocean. Some of the important elements of the programmes are theseasonal cycles of the Somali current system and the equatorial current system, the Arabian Seasurface temperature variations, cross-equatorial fluxes, the surface-layer dynamics, the exchangeof energy between the ocean and the atmosphere etc. The sea-level variations, the dynamics ofeddies and the transport processes, vertical and horizontal mixing, temperature and salinitydistribution and the upwelling dynamics of the area are also of significance in our understanding ofthe interannual variability of the monsoons. The monsoon-dependent ocean circulation and otherphysical characteristics of the waters of the area have important impacts on other characteristics,such as biological productivity, distribution of nutrients, etc.In addition to the climatic variability of the area, studies on problems such as the genesis ofcyclones in the Bay of Bengal, storm surges on the east coast of India, etc., will be of great interestand importance.53