Dynamics of Convective Entrainment in a Heterogeneously Stratified Atmosphere with Wind Shear

Shear and buoyancy are both known to contribute to the development of boundary layers, whose characteristics include turbulent mixing of scalar quantities within the layer. Purely shear-driven boundary layers include airflow over an airplane wing and stream flow over a bottom surface. Buoyancy-driven boundary layers include the atmospheric convective boundary layer (CBL) and the upper levels of the ocean from the surface to the thermocline. If there is no mean flow (relative to the upper and lower limits of these layers), the CBL can be considered to be purely buoyancydriven. For the atmosphere, pure cases of buoyancy-driven and shear-driven boundary layers are difficult to find. In most situations, both shear and buoyancy are contributors to the growth and the internal structure of the boundary layer. Appropriate understanding of the combined effects of shear and buoyancy on boundary layer dynamics is necessary to best represent CBL effects in numerical weather prediction models. This study explores the effects of wind shear on the growth and structure of the CBL and seeks to relate them within a general dynamical framework.