Transport variability of the ACC and teleconnection with the Southern Annular Mode (SAM) south of Africa.

To study the Antarctic Circumpolar Current (ACC) volume transport several cruises have taken place. The results of these cruises show snapshots without information about the time variability. To investigate the time variability of the ACC the Alfred Wegener Institute operates an array of Pressure Inverted Echo Sounders (PIES) along a satellite altimeter ground track south of Africa. PIES monitor ocean bottom pressure and acoustic travel time across the water column. A Gravest Empirical Mode (GEM, Meinen and Watts 1998) was applied to determine the geostrophic transport between the PIES. These time series were used to compute a transfer function between satellite Sderived transport and geostrophic transport. Satellite altimetry offers the possibility to calculate ACC transport between 1992 and 2010. A mean transport of 115 Sv and a variability of 7 Sv were derived for the Topex/Poseidon, Jason 1 and Jason 2 time period. A wavelet analysis shows that the ACC transport highly correlates with the winter and spring SAM index, whereas a direct correlation on a monthly scale could not be shown.