Hydrographic Characteristics of a Coastal Antarctic Transect in the Indian Ocean Sector

Abstract

We address results of the hydrographic measurements obtained from Expendable CTD (XCTD) probes deployed along a coastal Antarctic transect between Prydz Bay and India Bay during austral summer of 2013. The thermal structure indicated two upwelling zones: one centered at 38°E and another at 60°E; these entrain Circumpolar Deep Water (CDW) to shallow depths. The two bays are influenced by cyclonic circulation adjacent to the Amery Ice Shelf and in the Weddell Sea. The former promotes a cold front at 70°E which extends to deeper depths, while the latter promotes a cold front at 40°E in the upper 400 m. We encountered deep mixed layer (> 100 m) in low weak wind speed condition. The temperature and salinity profiles capture signatures of super cooled water in the Prydz Bay between 90-164 m and Antarctic Bottom Water at deeper depths (> 900m). CDW is the voluminous water mass detected in the study area. The research work, which is first of its kind pertaining to the coastal Antarctic sector by deploying XCTDs, will serve as benchmark for planning a detail survey in this region using a dedicated research vessel for deeper penetration of hydrographic recording instruments for a broader and 3-dimensional picture of the circulation and water mass transformation.