Daytime boundary layer evolution over mountainous terrain. Part II: numerical studies of upslope flow duration.

Abstract

Numerical simulations of upslope flow forming on the lee side of a heated mountain ridge, performed with a two-dimensional, dry version of the cloud model of Tripoli and Cotton, included a nocturnal inversion layer and ridgetop winds. Cross sections of potential temperature winds reproduced observations well. Runs with and without the inversion layer showed that this layer was important in the formation of upslope winds near the ground when ridgetop-level winds were present: the runs without an inversion layer never developed upslope flow on the lee slopes. Runs in which the upper-level winds were varied showed that the duration of the upslope flow on the lee slope bore an inverse relationship to upper-level wind speed. -from Author