A DEEP BOUNDARY CURRENT IN THE ARABIAN BASIN

Recently collected CTD data are supplemented by historical Nansen bottle data to examine the circulation of bottom water in the Arabian Basin. A deep western-boundary current is observed flowing southeastward below a mid-depth zero-velocity surface along the Carlsberg Ridge. A zero-velocity surface at potential isotherm 1.7-degrees-C is chosen on the basis of water-mass properties. However, the origin of the bottom water in the Arabian Basin cannot be determined in a like manner. The bottom water could enter from the Somali Basin through the Owen Fracture Zone, or from the Central Indian Basin through passages in the Chagos-Laccadive Ridge south of the equator. Application of the Stommel-Arons framework for deep-circulation dynamics to the basin suggests that the bottom water is supplied primarily through the Owen Fracture Zone.