Observations of the shelf break current in the southern Weddell Sea:
seasonal variability and mean state
Abstract
The Antarctic Slope Front and the associated Antarctic Slope Current are
central in determining the dynamics along and the exchanges across the
continental shelf break around Antarctica. Here, we present new,
four-year-long (2017-2021) records from two moorings deployed on the
upper part of the continental slope (530 m and 738 m depth) just
upstream of the Filchner Trough in the southern Weddell Sea. We use the
records to describe the mean state and the seasonal variability of the
shelf break current and the regional hydrography. We find that (i) the
current is bottom enhanced, (ii) the isotherms slope upwards towards the
shelfbreak, and more so for warmer isotherms, and (iii) the monthly mean
thermocline depth is shallowest in February-March and deepest in
May-June while (iv) the current is strongest in April-June. On monthly
timescales, we show that (v) positive (warm) temperature anomalies of
the de-seasoned records are associated with weaker-than-usual currents.
Our results contribute to the understanding of how warm ocean waters
propagate southward and potentially affect basal melt rates at the
Filchner-Ronne Ice Shelf.