John Marshall

Cecil and Ida Green Professor of Oceanography, MIT

ON THE RECIRCULATION OF THE SUB-TROPICAL GYRE

ON THE RECIRCULATION OF THE SUB-TROPICAL GYRE.

(MARSHALL, J and NURSER, G), QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, vol. 114, no. 484, pp. pages, 1988.

Abstract

A hydrographic section through the Gulf Stream and its recirculation to the south is interpreted in terms of an analytical model based on the baroclinic Fofonoff gyre, in which layers shielded from forcing are homogenized to a uniform value of potential vorticity. Given this simple paradigm of the circulation, the process of anticyclogenesis is studied in which seasonal changes in the volume of low potential vorticity waters accompany a steepening of the main thermocline and an intensification of the recirculating gyre. The consequences of the gyre intensification for the structure of the bowl, the circulation within it and the deep abyssal flow are investigated. It is shown that as the anticyclogenesis proceeds, there is a general southward shift of the current systems; the bowl of the circulation strikes the ocean floor further south and there is an intensification of the depth-independent recirculation tight in to the axis of the Stream. These changes in the structure of the recirculation are broadly in accord with observed seasonal variability associated with wintertime mode water production.

doi = 10.1002/qj.49711448408