Meteorological aspects of dust storms

Abstract

Dust emission requires the combination of deflatable soil material and near-surface wind speeds above the local emission threshold. Across the many dust source regions on Earth a number of generic meteorological phenomena can be identified and classified: (1) Large-scale monsoon-type flows associated with an acceleration towards a continental heat low, predominantly in late spring and early summer; (2) mobile synoptic-scale systems such as anticyclones, cyclones and their cold fronts, typically in late winter and spring; (3) gust fronts generated by outflow from moist convective storms, most common during the beginning of the summer rainy season; (4) intense dry convection in the daytime planetary boundary layer particularly during summer, leading to the generation of dust devils and dusty plumes. These processes can locally be modified by topographic effects and are usually characterised by marked diurnal cycles, for example caused by the development and subsequent breakdown of nocturnal low-level jets in areas of sufficiently large pressure gradients and stable nighttime conditions. In this chapter the different meteorological phenomena listed above will be explained and illustrated using ground-based observations, satellite data and measurements from field campaigns as well as data from meteorological models.