THE HIGH RESOLUTION THERMAL STRUCTURE OF THE POLAR FRONT REGION IN THE DRAKE PASSAGE DURING ANTARCTIC OPERATIONS 22 AND 23 (SOUTHERN SUMMER 2003 AND 2004)

Abstract

In Brazil several studies are being dedicated to many aspects of Antarctic oceanography and the Southern Ocean. Using Expandable Bathy-Thermographs (XBTs) data collected in the Drake Passage region, this study analyses the thermal structure of the Polar Front (PF) during the years of 2003 and 2004. The mean temperature of the water at the sea surface was 4,1 °C in the Subantarctic Zone (SAZ – North of the PF) and -0,4 °C in Antarctic Zone (AZ – South of the PF). Based in the methodology proposed by Kara et al. (2000) for computing the maximum temperature horizontal gradient it was determined that the PF was situated close to 58 °S in the period of this study. At depths higher than 200 m the AZ presents waters colder than 2 °C and about 2,5 ºC warmer than surface waters. At depths higher than 200 m the SAZ presents waters with temperature ranging from 2,5 to 3 °C and about 1 to 1,5 ºC colder than the surface waters. The AZ presents a more stable mixture layer down to 100 m depth where the top of the thermocline is located. The SAZ presents a thermocline spreading itself from surface to 200 m depth.