Surface temperature and salinity variations between Tasmania and Antarctica, 1993-1999

[1] Continuous surface temperature and salinity measurements have been collected onboard a supply ship between Tasmania and Dumont D'Urville, Antarctica, as part of the SURVOSTRAL program (Surveillance de l'Oce'an Austral). The ship makes 6-10 repeat sections per year from October to March for the period 1993-1999, and these measurements form the longest time series of spring and summer variations available in the Southern Ocean. The surface fronts are more clearly indicated with the salinity data than the temperature data. The Levitus climatological and Reynolds satellite monthly mean sea surface temperature data compare well with our surface temperature data: All data sets are dominated by the large-scale seasonal heating cycle with similar amplitude and phase. The SURVOSTRAL monthly mean sea surface salinity data show weak seasonal variations, except in the Antarctic Continental Zone where seasonal sea-ice variations introduce large surface freshwater fluctuations. The Levitus climatological surface salinity has too much seasonal variability and fails to reproduce the sharp fronts, the near-constant salinity in the Antarctic Zone, and the seasonal freshening near Antarctica. This has important consequences for projects that use Levitus climatology data to establish the surface salinity structure and water mass characteristics.