Northward undercurrent along west coast of India during upwelling - some inferences

Abstract

Utilizing hydrographic data covering several months from a section along 15 ᵒ N in the eastern Arabian Sea, a northward flowing undercurrent at the time of upwelling along the west coast of India has been identified from the downward tilt of the isotherms below the upwelling layer. This northward flow which appears to be weak occurs in the slope region between 100 and 150 m below the surface. Temperature ranging between 18ᵒ and 20 ᵒ C and a salinity minimum ranging between 35.14 and 35.4 x 10 ^-3 are found to be associated with this flow. The T-S relationship for selected stations vertically across the undercurrent shows two distinct water characteristics - a warm and high saline surface water and a low temperature, low saline subsurface water. This northward subsurface flow appears to be either absent or reversed during the downwelling season (Dec.-May) along this part of the coast.