On monitoring two major current systems of the north Indian Ocean using an array of deep-sea moorings

Abstract

The region between the southern tip of the Indian subcontinent and the equator links the Arabian Sea and the Bay of Bengal.A significant exchange of mass, heat and salt occurs in the region via two major current systems: the monsoon current (dominant annual cycle) and the equatorial current (dominant semi-annual cycle).This paper presents observations from deep-sea mooring programmes and describes the rationale for maintaining a mooring array along 77.4 �E to monitor both current systems.Analysis shows that the semi-annual to annual cycle transition occurs at 2-2.5 �N, with the winter monsoon current peaking at 5 �N, the summer monsoon current at 3-6 �N, and the equatorial current at 0-1 �N.Research highlights: 1.Ocean current observations are shown in the monsoon and equatorial currents regime at 77.4 �E.2.The transition between monsoon and equatorial current occurs at 2-2.5 �N.3.Summer (winter) monsoon current is strongest at 3-6 �N (5 �N).4.Minor expansion of existing mooring programmes to monitor two major current systems in the North Indian Ocean is proposed.