Hydrographical features of the southern and central Bay of Bengal during the transition period between winter and summer

Abstract

During Feb.-Mar. 1963, INS KISTNA has carried out its 6th and 7th oceanographic cruises in the southern and central parts of Bay of Bengal under the Indian Programme of IIOE. With the physical oceanographic data collected in these cruises, the general hydrographical features in the upper 500 metres are studied by preparing the vertical profiles of temperature, salinity and density (sigma t) along the 6 sections chosen for the purpose and discussing the vertical distribution of each parameter in the case of each section. In the upper 50 metres of the Eastern Bay and the Andaman Sea, a low salinity water mass (S33.0ppt, sigma 21.0), which could be tentatively named as the "Eastern Dilute Water of Indo-Pacific Origin", is encountered. Another water mass, which resembles the "Southern Bay of Bengal Water" with the salinity range 33.0-34.0 ppt and sigma t range 21.0-22.0 is identified in the upper 100 metres of the Southern Bay and the western and middle parts of the Central Bay. Throughout the region under study, the Indian Ocean Equatorial Water (T