Wind‐controlled export of Antarctic Bottom Water from the Weddell Sea

• Published in: Geophysical Research Letters
• Main Authors: Jullion, Loïc, Jones, Sam, Naveira Garabato, Alberto C., Meredith, Michael P.
• Other Authors: Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN), Nathional Oceanography Centre, University of Southampton, British Antarctic Survey (BAS), Natural Environment Research Council (NERC)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Antarctic; Drake Passage; Scotia Sea; South Scotia Ridge; Weddell; Weddell Sea; Antarc*
• Online Access: https://hal.archives-ouvertes.fr/hal-01255769; https://hal.archives-ouvertes.fr/hal-01255769/document; https://hal.archives-ouvertes.fr/hal-01255769/file/2010GL042822.pdf; https://doi.org/10.1029/2010GL042822

International audience [1] Recent studies suggest that the variability in Antarctic Bottom Water (AABW) properties in the Scotia Sea on time scales up to decadal may be linked to changes in the baroclinicity of the Weddell gyre, with vertical variations in the density structure at the gyre's northern edge acting to control the export of AABW over the South Scotia Ridge and toward the mid‐latitude South Atlantic. We test this hypothesis by analysing the AABW properties in fifteen occupations of the SR1b hydrographic section (1993–2009) in eastern Drake Passage alongside possible forcings as derived from atmospheric reanalysis data. We show that variability in the wind stress over the Weddell gyre leads changes in AABW properties in the SR1b section by approximately five months. The sign of the lagged correlation is consistent with the notion of the AABW export from the Weddell Sea being controlled by the gyre's baroclinic adjustment to wind forcing on time scales of several months. Variability in the regional winds is found to be closely linked to the Southern Annular Mode (SAM). These results suggest that there may be a causal relationship between the SAM's positive tendency observed in recent decades and the subsequent warming of AABW detected across much of the Atlantic Ocean.