Atmospheric Boundary Layer and Atmospheric Modelling

Atmospheric systems of various scales, from global circulation to boundary-layer turbulence, play an essential role in wind erosion. The general circulation of the atmosphere determines the global patterns of wind, precipitation, soil moisture, vegetation cover etc. and hence the global pattern of wind erosion, as discussed in Chapter 2. For individual wind-erosion events, wind shear near the surface is responsible for particle entrainment into the atmosphere, and turbulence in the atmospheric boundary layer is important for particle diffusion and deposition. Severe dust storms are mostly generated by intense meso-scale to synoptic-scale atmospheric systems, and the long-range transport of dust is dependent on the large-scale flow field. In this Chapter, we describe the basic aspects of the atmosphere that are relevant to wind erosion and give an outline of atmospheric modelling. The emphasis of the discussion is on the atmospheric boundary layer where the most important wind-erosion processes take place.