MOTIONS IN THE BOUNDARY LAYER UNDER THE GEOSTROPHIC MOMENTUM APPROXIMATION INCORPORATING A THREE-SECTION K DISTRIBUTION

By use of geostrophic momentum approximation,the analytical expressions of the wind distributionwithin the planetary boundary layer and the vertical velocity at the top of the boundary layer are obtainedwhen the distribution of eddy transfer coefficient k is divided into three sections:kz(z≤z<h),k(h≤z<h),and k(h≤z).The results are in agreement with the observations.In particular,the wind profile inthe surface layer(z≤z<h)coincides with the logarithmic distribution.The maximum angle between windsnear the surface and at the bottom of the free atmosphere is only about 30°.This work improves the work ofWu and Blumen(1982)who introduced the geostrophic momentum approximation to the boundary layer.Thesolutions in barotropic and neutral conditions have been also extended to the baroclinic and stratified atmosphere.