4 Large scale physical variability of the Benguela Current Large Marine Ecosystem (BCLME)

Abstract

Large-scale, multiyear climatic variations in the Benguela upwelling region have been observed from time to time and have been dubbed "Benguela Niños as an analogue to the Pacific event. The Benguela Nifio, like its Pacific counterpart, has a strong effect on regional fisheries and this in turn has led to an effort to forecast these events. Benguela Niños have been observed/reported in 1934, 1963, (1972/3), 1984, 1995. More recently, Florenchie et al. and Florenchie et al. have examined the nature of the 1984 and 1995 Benguela Niños using an ocean general circulation model together with satellite derived sea surface temperature (SST) and sea surface height (SSH) data, to show how they can be related to local and remote wind forcing. Their results suggest that a possible forecast lead time of two months exists for anticipating strong positive SST anomalies propagating from the equatorial region, polewards beyond the Angola Benguela Frontal Zone (ABFZ). Benguela Nifios represent the lowest frequency, largest-scale instance of variability in the BCLME. The main large scale physical features of the BCLME are summarized in this chapter. The main purpose of this chapter is to set the scene for a discussion of potentially forecastable aspects of major importance in the BCLME. Questions that are central to this discussion are formulated below.