Genesis of Major Dust Storms in West Africa during the Summer of 1974

摘要

The occurrence of major dust clouds over the western Sahara is associated with several characteristic features of the large scale synoptic conditions, including the isallobaric pattern as well as the flow patterns at the 850-700 mb layer and the surface. A necessary ingredient for the occurrence of dust appears to be the existence of a well developed and intense surface cyclone along the ITF south of the dust source region. These three features are incorporated in three synoptic models for dust generation. The models are: the general model (GM), the model without a trough (NTM) and the model with a trough (TM). Conditions resembling those in the TM appear to be the ones most frequently observed during dust episodes in GATE. (Author)