Zonal asymmetries in the African Easterly Jet

The African Easterly Jet has been extensively studied in recent years by major field programs, including AMMA. It has generally been treated as a single entity, a mid-level wind maximum that varies in intensity and latitude on a daily, seasonal, and interannual basis. This is the case in the long-term mean but in individual years two cores are apparent. The two cores show markedly different patterns of variability and links to rainfall in the region. The location and intensity of the western core are strongly influenced by the Guinea highlands. The eastern core, which shows a closer relationship to rainfall variability, appears to be influenced strongly by the presence of a low-level equatorial westerly jet that develops in wet years in response to inertial instability. The presence of two cores has many implications for wave activity over West Africa.