Some Climatological Aspects of West African Disturbance Lines During GATE

Abstract

The disturbance lines which occurred during the three phases of GATE over the eastern Atlantic Ocean and West Africa have been identified utilizing the excellent data from the SMS-1 geostationary satellite. The majority of these disturbance lines generated and decayed over land. Genesis occurred predominantly in the afternoon over land and in the early morning over water. They develop to the north of the cloud systems associated with the southwest monsoon, where the moist layer is shallow and the overriding dry air favors the production of downdrafts by the evaporation of precipitation and genesis is to a large extent dependent on insolation and low-level convergence associated with traveling waves.