The southward intrusion of North Pacific Intermediate Water along the Mindanao coast

Abstract

A tongue of low salinity intermediate water was observed along the coast of Mindanao during the WEPOCS III experiment in June and July 1988. The tongue, delineated by a discontinuity in θ-S relations, is a southward intrusion of water at 26-27 σθ. It is the Northern Hemisphere counterpart of the northward flow of Antarctic Intermediate Water in the New Guinea Coastal Undercurrent. It is seen entering the Celebes Sea near 5°N at the southern tip of Mindanao, after which it circulates within the Celebes Sea. Relatively fresh water at 26.55 σθ is seen continuing to flow toward the Makassar Strait and into the Indonesian Throughflow, although some fraction mixes with intermediate water of equatorial Pacific and South Pacific origin and flows eastward in the northern subsurface countercurrent. The tongue plays a part in the exchange of water at intermediate density between the tropical and subtropical gyres. -from Authors