Physical and biological variability in the Namibian upwelling system: from October 1997-October 2001

Abstract

The monthly and spatial patterns of chlorophyll concentration have been analysed for the northern Benguela upwelling system, which is characterised by its strong seasonality. Sea-viewing Wide Field-of-view Sensor data have been used to determine temporal patterns and to identify optimal conditions for chlorophyll production from October 1997 to October 2001. These data have been studied jointly with the sea surface temperature (SST) as an indicator of the physical variability in the region. The chlorophyll concentration did not present the strong seasonality of the physical environment but showed temporal and spatial optimal conditions. The highest chlorophyll concentration areas were found where and when the conditions of the water column were more stable. Although the time series is still too short to allow the designing of any conceptual model of the factors controlling the primary production of this region, it is long enough to permit us to conclude that it is not limited by the nutrient supply but by the stability of the water column.