The atmospheric boundary layer

A review is presented of the turbulent structure and dynamics of the atmospheric boundary layer. First attention is given to some general aspects of the boundary layer in relation to its role in the dynamics of the atmosphere. The general characteristics of the boundary layer, such as turbulence are discussed and the equations for a horizontally homogeneous boundary layer are formulated. Based on a simple closure of the turbulent fluxes a solution of these equations, in the form of the Ekman profile, is presented. The structure and dynamics of boundary layer prototypes; such as the surface layer, the neutral, the convective and the stable boundary layer, are investigated. Within each scaling regime the appropriate scaling parameters are defined and scaling expressions are formulated and compared with experimental data. The boundary-layer dynamics of each prototype is considered. In addition attention is given to some special topics such as the effect of roughness and vegetation, coherent structures and clouds. Finally the non-stationary and inhomogeneous boundary layer is discussed.