92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012: 11:45 AM
Mechanisms of Climate Variability in Western Equatorial Africa
Room 354 (New Orleans Convention Center )
Amin Dezfuli, Florida State University, Tallahassee, FL; and S. E. Nicholson

Compared to other regions of the tropics, relatively little is known about meterological processes in western equatorial Africa. This stands in stark contrast to more eastern sectors, where climatic variability, its mechanisms, and links to the general circulation have all been extensively studied. This paper presents the results of the first study to ever examine interannual variability in western equatorial Africa on a regional and seasonal basis. The results confirm the heterogeneity within the region and demonstrate both remote and local forcing. The degree to which either forcing prevails is strongly dependent on season and location. Three major conclusions result from the study. 1) Associations are evident between rainfall variability and the tropical Atlantic, Pacific, and Indian oceans. 2) Changes in the east-west zonal circulations cells (displacement and intensity) are major factors. 3) Strong associations between SSTs and rainfall tend to reflect the influence of circulation changes on both variables, rather than direct forcing by SSTs. 4) There is a strong tendency for wet years to be linked to an intensification of the Tropical Easterly Jet and equatorial westerlies and a weakening of the mid-tropospheric easterlies.

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