TOWARDS ACHIEVING AN IN-SEASON FORECAST OF THE WEST-AFRICAN PRECIPITATION

This study investigates inter-station correlation of monthly precipitation across West Africa from the Atlantic coast, through the Sahel to the Saharan border. The spatial distribution of correlation coefficients resulting from this exercise falls into three dinstinct regimes which demarcate the domains of operation of the important atmospheric mechanisms affecting precipitation in the region. A two-month lag correlation maximum occurs between precipitation of the Southern stations (e. g. Lagos and Bohicon) and of those in the Sahel. This suggests that the Sahelian precipitation can be forecast from that observed in the South earlier in the rainy season. In the face of the lack of definitive trends and periodicities in the Sahelian long term precipitation records [2] this relationship holds promise for economic and agricultural planning in this drought affected zone. An auto-correlation of various stations' data over the decade 1951-1960 indicates no persistence but a seasonal persistence from June-August to September-November (r=0.49) is found in the Niamey data for 1951-1973. © 1979 Springer-Verlag.