Three separate studies concerning flow over inhomogeneous terrain are presented. Two-dimensional nonlinear models were constructed and then integrated numerically. In the first study, the atmospheric boundary layer flow over terrain with a discontinuous variation in roughness was studied. A time dependent numerical model, using Blackadar's expression of mixing length and assuming no dynamic pressure effect and no vertical displacement of the zero velocity level at the lower boundary, was integrated until a steady-state situation was reached. The results agree with earlier theoretical work of Panofsky and Townsend and also with observations by Sterns and Lettau. The second study represents an attempt to solve a problem similar to the one just described using a steady-state model. An iterative method for solving the equations was derived. In addition, the dynamic pressure effect was also incorporated. The results show satisfactory agreement with those of Panofsky and Townsend. It is found that the dynamic pressure effect causes an apparent horizontal smoothing of the motion field. In the third study, the effect of an isolated hot surface (10 km wide) on the motion and temperature field is investigated. The model is time dependent and is based primarily on a sea breeze model by Estoque. As expected, the results show that the intensity of the upward motions which are induced is inversely proportional to the strength of the prevailing flow. The perturbations in both the temperature and velocity fields extend to several tens of kilometers downwind of the hot surface.

The book gives a comprehensive and lucid account of the science of the atmospheric boundary layer (ABL). There is an emphasis on the application of the ABL to numerical modelling of the climate. The book comprises nine chapters, several appendices (data tables, information sources, physical constants) and an extensive reference list. Chapter 1 serves as an introduction, with chapters 2 and 3 dealing with the development of mean and turbulence equations, and the many scaling laws and theories that are the cornerstone of any serious ABL treatment. Modelling of the ABL is crucially dependent for its realism on the surface boundary conditions, and chapters 4 and 5 deal with aerodynamic and energy considerations, with attention to both dry and wet land surfaces and sea. The structure of the clear-sky, thermally stratified ABL is treated in chapter 6, including the convective and stable cases over homogeneous land, the marine ABL and the internal boundary layer at the coastline. Chapter 7 then extends the discussion to the cloudy ABL. This is seen as particularly relevant, since the extensive stratocumulus regions over the subtropical oceans and stratus regions over the Arctic are now identified as key players in the climate system. Finally, chapters 8 and 9 bring much of the book's material together in a discussion of appropriate ABL and surface parameterization schemes in general circulation models of the atmosphere that are being used for climate simulation.

A two-dimensional time dependent numerical model of the atmospheric boundary layer is formulated and used to investigate various characteristics of air motion when a change occurs in roughness and/or temperature characteristics of the underlying surface. The integrations have been carried out for steady-state situations also. The model incorporates the effects of penetrative convection, diabatic influence associated with small-scale eddy diffusion, and pressure effects induced by horizontal nonuniformity of terrain in temperature and roughness. The results show that warm surfaces do not necessarily increase the height of internal boundary layers in the vicinity of surface discontinuity. The effects of discontinuity are quite appreciable at large fetches downwind from the discontinuity. (Author).