A Model of Katabatic Winds

Abstract

A new model of katabatic winds is presented. A hydraulic approach is employed in which the detailed vertical structure of the flow is replaced by a quiescent stably stratified environment and an equivalent flowing layer which is subject to sustained layer cooling, surface stress and interfacial entrainment. A scaling which contains most of the parametric behavior is found. It shows that interfacial entrainment is the dominating retardation mechanism of the flow and that surface stress may be relatively unimportant. Steady solutions are presented to show that katabatic winds are essentially supercritical on all practical slopes (slope angles >0.1°), and are affected by ambient stratification only at large distances. The model is in satisfactory quantitative agreement with the limited field data available.