Response of the coastal waters off Karwar to summer monsoonal forcing during 1989

Time series measurements made onboard R. V. Gaveshani during June (onset phase) and September (withdrawal phase) 1989 were utilized to study the changes in the thermohaline and current fields off Karwar. Intense upwelling is noticed during the monsoon season (vertical velocity of -1.3 x 10−3 cm s−1) which is mainly induced by the prevailing westerly-northwesterly winds. Despite upwelling, temperature in the surface layers did not exhibit appreciable change. Net oceanic heat gain during withdrawal phase (97 Wm−2 Z) offset the cooling due to upwelling. The subsurface salinity maxima (36.61 PSU) noticed around 40 m in the onset phase shoaled to 25 m and a well defined core developed by the end of the monsoon season. Prominent bottom isothermal layers (below 60 m) are observed in both phases. Temperature and salinity values of this layer suggested the presence of northward flowing undercurrent.