Observations of low-frequency currents and continental shelf waves along the west coast of South Africa

Abstract

Since 1982 the Sea Fisheries Research Institute has conducted a number of current-meter studies in the Cape Columbine-St Helena Bay region to determine the coastal current response to local wind-forcing. The subsurface flow is examined with data selected from two multi-mooring experiments, July/August 1982 and October 1984–March 1985, and from a continuous monitoring programme which commenced in December 1982. There is evidence of energetic, barotropic shelf waves responding to alongshore wind reversals. These are primarily associated with the easterly passage of atmospheric fronts in winter and with activity of coastal lows in summer. Further, temporal current variability is shown to be modulated by a perennial poleward undercurrent, which itself varies in intensity on an interannual time scale. © 1987 Taylor & Francis Group, LLC.