Atmospheric Boundary-Layer Climates and Interactions with the Land Surface

The purpose of this article is to provide an overview of the relevant processes and interactions in the Atmospheric Boundary Layer (ABL) over land. Modeling principles for the ABL are summarized and discussed, including the formulation and role of the surface fluxes. It is shown that both the ABL and the coupled soil-vegetation-atmosphere system can be well represented in the well-defined cases examined. The interactions between the ABL and the land surface are illustrated with the role of soil moisture on boundary-layer cloud initiation. As such, a new analytical development is discussed and illustrated for the tendency of relative humidity at boundary-layer top. Typically, increased soil moisture leads to a higher potential for boundary-layer clouds, but in some cases, the largest potential for boundary-layer clouds is predicted over dry soils. For readers not familiar with atmospheric turbulence and meteorological definitions, some background is given as well.