Continental-scale Sahara dust outbreak

By Jochen Kerkmann (EUMETSAT)

Wintertime cold air outbreaks from Europe to Northern Africa frequently lead to large-scale dust storms over the Sahara. The dust storm shown below was one of the biggest dust outbreaks observed in the last years, similar in size and appearance to the dust storms of 3–10 March 2004 and 5–8 January 2005.

It started on 5 March 2006 over Morocco and Algeria when the cold front of a cyclone over the Balearic Islands reached northern Africa. During the following days, the cyclone moved from the western to the eastern Mediterranean Sea and the cold front crossed northern Africa from west to east, with the dust storm following it.

On 9 March the dust storm finally reached the Middle East. With the built-up of a high pressure system in the cold air over north-west Africa, a strong north-easterly flow over the central and southern Sahara generated further dust storms in the area of the Bodele depression and Agadez, where huge quantities of dust were picked up and carried towards Niger, Mali, Burkina Faso and Nigeria.

The further progress of the dust towards the Gulf of Guinea was stopped by a southerly flow in the area of the Ivory Coast, which led to the formation of a convergence line over Northern Ghana (see ECMWF surface pressure/winds analysis). The strong colour difference across this convergence line (from pink to dark blue) is due to the different airmass characteristics: cold, dry, dusty air to the north and warm, moist air to the south of the boundary. On the following day (9 March), the dust was blown far out over the Atlantic Ocean where it was 'sucked' into a cyclone situated between the Canary and the Cape Verde Islands.

Additional content

Dust RGB with ECMWF surface pressure/winds analysis:
Dust RGB with ECMWF surface pressure/winds analysis: close-up view
Dust outbreak on the Atlantic (9 March 2006, 12:45 UTC)
Dust storm reaches the Middle East (9 March 2006, 12:45 UTC)