abstract
Simultaneous station lines have been carried out by two vessels between South Africa and Antarctica to study details of the thermal fronts in the upper ocean layers. This cruise was undertaken within a time interval of three months and thus facilitated the investigation of temporal changes in the fronts. Five well-defined fronts were located and are described. The frontal morphologies of the Subtropical Convergence, the Sub-Antarctic Front and the Antarctic Polar Front show development of a step-like structure with the progress of summer. The possibility that the Sub-Antarctic Front south of Africa extends to at least a 1 000 m depth is indicated.