Case Studies of Tropical Atlantic Surface Circulation Patterns During Recent Sub-Saharan Weather Anomalies: 1967 and 1968

Abstract

Abstract Sub-Saharan West Africa (10–20°N) receives moisture from the tropical Atlantic via low-level south-westerly flow across the southwestern coast of West Africa. This paper utilizes a 1arge data set to identify the tropical Atlantic (30°N–30°S) surface atmospheric and oceanic patterns for two years when sub-Saharan West Africa experienced anomalous weather. Comparison is made with 60-year (1911–70) average fields. The following tropical Atlantic surface features were located/centered 300–500 km further south in the deficient sub-Saharan rainy season (July-September) of 1968 than the more abundant 1967 rainy season— the kinematic axis between the Northern and Southern Hemisphere trades, the near-equational convergence tune, the near-equatorial pressure trough, the zone of maximum sea surface temperature (SST), the mid-Atlantic maxima of precipitation frequency and total cloudiness, and the center of the North Atlantic subtropical high. Sixty-year mean positions of these features were generally interm...