Slope Winds in Veracruz

Abstract

Detailed boundary-layer measurements are presented to show how slope winds affect the regional climate in central Veracruz state, Mexico. Observations include the growth of an anabatic convective boundary layer in summer, production of katabatic storm outflows moving contrary to prevailing easterlies, and detailed sequences of the wind and temperature in katabatic wind. The onset time for downslope motion is just before dawn after a clear night in summer, although observed within three hours of clear-sky conditions in winter. The delay in onset is most likely due to opposing upslope flow in summer. The vertical structure of the katabatic wind resembles that of entraining gravity flows. We make a distinction between an inner katabatic layer, near the level of wind maximum, in which the buoyancy force is large, and an entraining outer layer above, that is primarily forced by the inner layer.