The imprint of Southern Ocean overturning on seasonal water mass variability in Drake Passage

• Main Authors: Dafydd Gwyn Evans, Jan D. Zika, Alberto C. Naveira Garabato, A. J. George Nurser
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Drake Passage; Southern Ocean; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.666.3454; http://eprints.soton.ac.uk/372139/1/jgrc20971.pdf

Abstract Seasonal changes in water mass properties are discussed in thermohaline coordinates from a seasonal climatology and repeat hydrographic sections. The SR1b CTD transects along Drake Passage are used as a case study. The amount of water within temperature and salinity classes and changes therein are used to estimate dia-thermal and dia-haline transformations. These transformations are considered in com-bination with climatologies of surface buoyancy flux to determine the relative contributions of surface buoyancy fluxes and subsurface mixing to changes in the distribution of water in thermohaline coordinates. The framework developed provides unique insights into the thermohaline circulation of the water masses that are present within Drake Passage, including the erosion of Antarctic Winter Water (AAWW) during the summer months and the interaction between the Circumpolar Deep Waters (CDW) and Antarctic Intermedi-ate Water (AAIW). The results presented are consistent with summertime wind-driven inflation of the CDW layer and deflation of the AAIW layer, and with new AAIW produced in the winter as a mixture of CDW, rem-nant AAWW, and surface waters. This analysis therefore highlights the role of surface buoyancy fluxes in the Southern Ocean overturning. 1.