Satellite observations of the Agulhas Current and episodic upwelling south of Africa.
Sea surface temperature changes in continental shelf and deep ocean environments south of Africa were monitored with calibrated and atmospherically corrected thermal infrared satellite data from October 1983 to April 1984. The Agulhas Current played a dominant role in sea surface warming of southest Atlantic Ocean water into the southeastern Atlantic Ocean waters between October and January. Westward penetration of Agulhas Current surface water into the southeast Atlantic Ocean was greatest in April 1984 in association with higer than normal atmospheric sea level pressure south of the continent. Positive surface temperature anomalies of at least 4°C occurred west of 20°E as a result of this intrusion. Simultanesouly, large-scale upwelling was observed over the Agulhas Bank. The evolution, spatial characteristics and persistence of abnormal upwelling events were assessed with satellite data, coastal temperatures and wind measurements in comparison with climatological means. The cool anomalies detected were primarily attributed to an abnormal prevalence of easterly winds over the Agulhas Bank early in 1984.