Mesoscale thermal structure of the polar front zone in Drake Passage during the austral summer of 1976

Abstract

The boundary between the Subantarctic and Antarctic surface waters within the Southern Ocean is known as the Polar Front. This front lies within a complex transition region referred to as the Polar Front Zone (PFZ). The Polar Front and PFZ have been the subject of much interest and debate almost since oceanographic studies in the Southern Ocean began. Vertical sections of temperature across the PFZ presented in the literature have revealed a variety of complex thermal structures which have led to different interpretations of both the basic structure and the dynamics of the PFZ. A review of these evolving ideas about the Polar Front, the PFZ and the Antarctic Circumpolar Current is presented. In the austral summer of 1976 repeated expendable bathythermograph surveys of the PFZ in Drake Passage were made aboard AGS Yelcho as part of the First Dynamic Response and Kinematics Experiment. These surveys were carried out quickly enough to allow changes in mesoscale thermal structure to be monitored as they occurred. This data set, combined with observations obtained..