The application to micrometeorology of the theory of turbulent flow over rough surfaces

摘要

AbstractIt is now well established that turbulent flow near the surface of the earth is usually of the type known as “aerodynamically rough”, and the present paper discusses the implications of this for diffusion. The various theories of rough flow are discussed and the conclusion reached that the formulation due to Rossby and Montgomery, in which the influence of the surface irregularities dies out with height, is the treatment most appropriate for meteorology, because of the relatively great depth of the layers dealt with as compared with wind tunnel boundary‐layer investigations. It is shown that the introduction of a characteristic parameter termed by the author themacroviscosity, defined as the product of the friction velocity and the roughness length, enables a single logarithmic profile to be defined for both rough and smooth flow. Finally, the theory of atmospheric diffusion previously advanced by the writer for smooth flow is extended to rough flow in conditions of neutral equilibrium, and shown to be in good agreement with observ