Effects of diabatic cooling in a shear flow with a critical level

Abstract

The response of a two-dimensional, stably stratified shear flow to diabatic cooling, which represents the evaporative cooling of falling precipitation in the subcloud layer, is examined using both a linear analytical theory and a nonlinear numerical model. In the nonlinear numerical simulations, it is found that the response of the atmosphere to a steady cooling in a shear flow may be categorized as either a stationary cold pool or a density current, depending upon the strength of the effective cooling. Nonlinearity appears to reduce the wave disturbance below the critical height and above the cooling top, while it tends to strengthen the density current or cold pool near the surface. -from Authors