MICROMETEOROLOGICAL CHANGES ASSOCIATED WITH VEGETATION REMOVAL AND INFLUENCING DESERT FORMATION

The effects of vegetation removal on the energy balance components, soil and air temperatures, and atmospheric vapour densities are predicted using a recently developed analytical theory. The results show that the sum of daily average sensible and latent heat flux densities decreases as the surface resistance and albedo increase and the surface roughness decreases, which according to some numerical models implies reductions in rainfall. For a dry surface daytime atmospheric heating decreases with vegetation removal because albedo and soil admittance increase and atmospheric admittance decreases; according to another model this should reduce precipitation. The results show that surface temperature is not an appropriate diagnostic measure of sensible heat flux density, even under constant meteorological conditions, when changes in surface roughness also occur. Analysis of some surface temperatures measurements made in the Negev and the Sinai suggests that understanding the turbulent processes occurring in the roughness sublayer, when the surface is partially covered with vegetation, is critical in assessing the micrometeorological changes associated with vegetation removal and desert formation. © 1990 Springer-Verlag.