 The effect of the Tibesti massif is clearly evident in creating a split in the low-level easterly flow north and south of these mountains.While the jet feature is pronounced over the Bodele, it is absent from other longitudes over west Africa along 18 N. It is therefore a feature which uniquely overlies the greater Bodele region, downwind of the mountains of Chad.The Bodele Low Level Jet undergoes a marked seasonal cycle.