FN Archimer Export Format PT J TI Coherent seasonal acceleration of the Weddell Sea boundary current system driven by upstream winds BT AF Le Paih, Nicolas Hattermann, Tore Boebel, Olaf Kanzow, Torsten Lüpkes, Christof Rohardt, Gerd Strass, Volker Herbette, Steven AS 1:1;2:1,2;3:1;4:1,3;5:1;6:1;7:1;8:4; FF 1:;2:;3:;4:;5:;6:;7:;8:; C1 Alfred Wegner Institute ,Germany Norwegian Polar Institute ,Norway Bremen University ,Germany Laboratoire d’Océanographie Physique et Spatiale (LOPS), IUEM, Univ. Brest, CNRS, IRD, Ifremer, France C2 INST A WEGENER, GERMANY NORWEGIAN POLAR INST, NORWAY UNIV BREMEN, GERMANY UBO, FRANCE UM LOPS IN WOS Cotutelle UMR copubli-europe IF 3.405 TC 15 UR https://archimer.ifremer.fr/doc/00652/76398/77436.pdf https://archimer.ifremer.fr/doc/00652/76398/77437.pdf LA English DT Article DE ;Southern Ocean;Weddell Sea;Antarctic slope current;surface stress;flow strength;teleconnection AB The Weddell Sea is of global importance in the formation of dense bottom waters associated with sea‐ice formation and ocean‐ice sheet interaction occurring on the shelf areas. In this context, the Weddell Sea boundary current system (BCS) presents a major conduit for transporting relatively warm water to the Weddell Sea ice shelves and for exporting {some modified form of Wedell Sea deep and bottom waters into the open ocean. This study investigates the downstream evolution of the structure and the seasonality of the BCS along the Weddell Sea continental slope, combining ocean data collected for the past two decades at three study locations. The interannual‐mean geostrophic flow, which follows planetary potential vorticity contours, shifts from being surface‐intensified to bottom intensified along‐stream. The shift occurs due to the densification of water masses and the decreasing surface stress that occurs westward, towards the Antarctic Peninsula. A coherent along‐slope seasonal acceleration of the barotropic flow exists, with maximum speed in austral autumn and minimum speed in austral summer. The barotropic flow significantly contributes to the seasonal variability in bottom velocity along the tip of the Antarctic Peninsula. Our analysis suggests that the winds on the eastern/north‐eastern side of the gyre determines the seasonal acceleration of the barotropic flow. In turn, they might control the {export} of Weddell Sea Bottom Water on seasonal time‐scales. The processes controlling the baroclinic seasonality of the flow need further investigation. Plain Language Summary In the Weddell Sea, large amounts of seawater are cooled to become dense and sink, carrying signals of human induced changes such as atmospheric carbon into the abyss of the ocean. Understanding the variability of the ocean currents at the Antarctic continental margin is critical because it controls both the export of the dense water formed in these areas and the access of warm water that may melt the Antarctic Ice Sheet. This study investigates the structure and the seasonality of the flow at the continental margin in the Atlantic sector of the Southern Ocean, using in situ observations upstream and downstream of the dense water formation regions. Following the bathymetry, ocean currents flow from East to West along the continental shelf edge. As water densifies along this path, the flow speed changes from being maximum at the ocean surface to be maximum at the bottom. The depth‐averaged current varies with a synchronized seasonality along the continental shelf break, reaching a maximum in austral autumn. Our analysis suggests that the winds on the eastern/north‐eastern margin drives the seasonality of the depth‐averaged flow along the shelf break, significantly contributing to changes in bottom velocity near the export region. PY 2020 PD OCT SO Journal Of Geophysical Research-oceans SN 2169-9275 PU American Geophysical Union (AGU) VL 125 IS 10 UT 000612077200038 DI 10.1029/2020JC016316 ID 76398 ER EF