Transport and variability of the Antarctic Circumpolar Current south of Africa.

• Published in: Journal of Geophysical Research
• Main Authors: Swart, Sebastiaan, Speich, Sabrina, Ansorge, Isabelle J., Goni, Gustavo J., Gladyshev, Sergey, Lutjeharms, Johann R. E.
• Other Authors: Department of Oceanography Cape Town, University of Cape Town, Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML), National Oceanic and Atmospheric Administration (NOAA), Shirshov Institute of Oceanology, Shirschov Institute of Oceanology
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Antarctic; The Antarctic; Antarc*
• Online Access: https://hal.science/hal-00405905; https://doi.org/10.1029/2007JC004223

International audience Data from five CTD and 18 XBT sections are used to estimate the baroclinic transport (referenced to 2500 dbar) of the ACC south of Africa. Surface dynamic height is derived from XBT data by establishing an empirical relationship between vertically integrated temperature and surface dynamic height calculated from CTD data. This temperature-derived dynamic height data compare closely with dynamic heights calculated from CTD data (average RMS difference = 0.05 dyn m). A second empirical relationship between surface dynamic height and cumulative baroclinic transport is defined, allowing us to study a more extensive time series of baroclinic transport derived from upper ocean temperature sections. From 18 XBT transects of the ACC, the average baroclinic transport, relative to 2500 dbar, is estimated at 90 ± 2.4 Sv. This estimate is comparable to baroclinic transport values calculated from CTD data. We then extend the baroclinic transport time-series by applying an empirical relationship between dynamic height and cumulative baroclinic transport to weekly maps of absolute dynamic topography derived from satellite altimetry, between 14 October 1992 and 23 May 2007. The estimated mean baroclinic transport of the ACC, obtained this way, is 84.7 ± 3.0 Sv. These transports agree well with simultaneous in-situ estimates (RMS difference in net transport = 5.2 Sv). This suggests that sea level anomalies largely reflect baroclinic transport changes above 2500 dbar.