Measurements of Currents along the Equator in the Indian Ocean

Abstract

IN recent years large, high-speed, eastward flows beneath the surface along the equator have been discovered and/or rediscovered¹. The structure of the Cromwell Current in the central and eastern Pacific has been described in some detail². The current is symmetrical about the equator, has a transport as great as 40 × 10⁶ m³/ sec and has a maximum speed in the thermocline of about three knots. The current appears to be steady and to be in geostrophic balance to within a half a degree of the equator. The distributions of oxygen, salinity and other properties indicate upwelling of water along the equator and strong vertical mixing. The observations in the Atlantic Ocean indicate that the current structure there is remarkably similar³.