Planetary Boundary Layer Winds in Baroclinic Conditions

Abstract

Systematic stratifications and analyses of low-level radiosonde data are performed for portions of the eastern half of the United States. The procedures are designed to specify changes in the planetary boundary layer wind profile resulting from variations in baroclinicity. The angle between the winds and isobars, the ageostrophic wind components, the surface stress, and the surface wind speeds are all shown to be functions of the orientation of the thermal wind vector relative to the surface geostrophic wind. These variations are consistent with a mixing-length model of the additional turbulent momentum transport initiated by the vertical shear of the geostrophic wind.