Atmospheric controls on mineral dust emission from the Bodele depression, Chad: The role of the low level jet

Atmospheric aerosols play an important though uncertain role in the Earth's climate system. The Bodele Depression in Chad stands out as the planet's largest source of dust, yet very little is known about the atmospheric circulation that maintain this source. We investigate what key large-scale features of the circulation over the Bodele account for its primacy as a mineral aerosol source. We show, for the first time, the structure and characteristics of the Bodele Low Level Jet (LLJ) which has a maximum speed near 18 degrees N, 19 degrees E at 925 hPa. It is strongest in the northern winter, receding with the advance of summer in phase with dustiness in the Bodele. Variability of dust over the Bodele occurs contemporaneously with the ridging of the Libyan High and pulsing of the pressure gradient which drives the northeasterlies in which the LLJ is embedded.