West African Rainbelt Variation

[摘要] Tropical West African rainfall data at a one-degree latitude interval within the range 4°N-19°N, averaged over the longitude band of 5°W-5°E, are updated through 1993 by using monthly station rainfall data for the July-September period. Making use of the latitudinal rainfall data, the West African rainbelt indices for 1919-1990 are calculated, (i. e., the latitude of its center of gravity and the total rainfall that occurs over the entire rainbelt zone).The Sahelian droughts for 1980-1984 are primarily associated with weakened convection over the entire West African rainbelt zone, while the southward retreat of the rainbelt plays a secondary role in the drought conditions. The slight increase in Sahelian rainfall for 1988-1989 is related to the near-normal position and total rainfall of the rainbelt. During the late 1980s, the increase in rainfall was widespread over the tropical latitudes of West Africa, while it was more evident south of the Sahel than in the Sahel.

[学科分类] 大气科学