Observations of an Anticyclonic Eddy of 18°C Water in the Sargasso Sea

Abstract

Observations have been made of a lens of 18°C water in the Sargasso Sea near 30°N, 69°W. The lens was nearly isothermal and isohaline and was embedded in the more typical weakly stratified 18°C water in the area. It was more than 500 m thick and 170 km in diameter. The lens was moving south-southwest at 3.8 km day?1 and was rotating anticyclonically with speeds up to 50 cm s?1. A smaller lens of water near 16°C was located concentrically below the major eddy. The 14°C isotherm in the main thermocline was depressed 300 m below its level in the surrounding area, and the 20°C isotherm in the seasonal thermocline was raised 50 M. Significant anticyclonic flow occurred as deep as 850 m in the thermocline. These observations confirm previous sparse evidence of eddies of this type. It has been suggested that they are generated near the Corner Rise Seamounts. We speculate that the observed feature is the remnant of an eddy formed by a convection cell of 18°C water possibly generated near the New England Seamount Chain during the previous winter.