Cloud Cells by Data of Satellite Measurements and Convective Energy Balance on Invasion of Cold Air into the Atmosphere over the Black Sea

Abstract

This paper considers a typical case of winter cold air invasion into the Black Sea region in January 2010. Using the WRF numerical model, the intensive convection over the sea on January 25 has been reproduced and the simulation results have been verified using satellite data on cloudiness, cloud top temperature, and specific humidity. It has been shown that, according to both the modeling results and the satellite data, mixed convection over the sea occurred but with the prevalence of cells playing the main part in the mixing in the atmospheric boundary layer (ABL). The cloud top height has been determined both by satellite data and by simulation results; it has been shown that the model reproduces the observed increase in the cloud top height over the sea with the distance from the coast. Spectral analysis of the vertical convective moisture flux fields has shown that the model correctly reproduced the horizontal size of cloud structures near the shore. It was found from the modeling results and satellite pictures that the horizontal size of convective cells over the sea increased downwind. The main components of the convective kinetic energy balance in the atmospheric boundary layer have been considered: energy generation due to pressure pulsations and work of the buoyancy force, as well as the decrease in energy due to turbulent diffusion and convective advection. It has been shown how these quantities varied with height and with the distance from the shore.