Atmospheric effects in the Angola-Benguela frontal zone

The Angola-Benguela Front is the generic border between, on the one hand, the Benguela Current and the coastal upwelling regime along the southwest African coastline and, on the other hand, the warm, southward flowing Angola Current. This frontal zone has a variable morphology, geographic location, and thermal characteristics. It has been suggested that this variability may be related to changing wind patterns. We have studied the thermal characteristics of the surface expression of the frontal zone for a 74-day period using daily thermal infrared images and compared-these to wind patterns from synoptic weather maps. There is little correlation between the location of the northern and the southern front that form the envelope for this frontal zone. The location of the southern front largely determines the thermal gradient across the entire frontal zone. Large short-term displacements in the geographic location of the frontal zone as well as short-term variations in its thermal characteristics are shown to be strongly correlated to the atmospheric pressure gradient of the South Atlantic anticyclone with a 1-day lag period. This is true irrespective of the latitude changes of the center of the South Atlantic anticyclone.