Upwelling and the occurrence of cold water around Cape Recife, Algoa Bay, South Africa

Abstract

Between February 1989 and March 1990 a study was undertaken to investigate sea temperature variability around Cape Recife, Algoa Bay, during and after upwelling events. Data were collected by moored thermistors and during a ship's cruise, and wind measurements were made at Cape Recife and Bird Island. Results confirmed upwelling off the southern shoreline of Cape Recife during easterly or north-easterly winds. When the wind switched to westerly or south-westerly, upwelling relaxed and cold water that had broken the surface during upwelling was dispersed eastwards towards the point of Cape Recife. Within a few hours of the change in wind direction to westerly, cold water was observed along the Algoa Bay shoreline of Cape Recife. The influence of wind-forcing and Kelvin waves on upwelling and the emergence of cold water along the Bay-side shoreline of the cape are discussed.