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).

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.

Based on more than 20 years of research and lecturing, Jordi Vil...-Guerau de Arellano and his team's textbook provides an excellent introduction to the interactions between the atmosphere and the land for advanced undergraduate and graduate students and a reference text for researchers in atmospheric physics and chemistry, hydrology, and plant physiology. The combination of the book, which provides the essential theoretical concepts, and the associated interactive Chemistry Land-surface Atmosphere Soil Slab (CLASS) software, which provides hands-on practical exercises and allows students to design their own numerical experiments, will prove invaluable for learning about many aspects of the soil-vegetation-atmosphere system. This book has a modular and flexible structure, allowing instructors to accommodate it to their own learning-outcome needs.