Penetrative turbulent convection over a heat island in a stably stratified environment

A three-parameter model of the turbulent momentum and hear transport is formulated to describe the circulation pattern over a heat island in a calm and stably stratified environment. The turbulent kinetic energy (TKE) E = 1/2 <u(i)u(i)>, its spectral dissipation epsilon, and the variance of turbulent temperature fluctuations < theta (2)> are found from differential equations, which provides a correct modeling of transport processes in the entrainment layer with an antigradient heat flux. The turbulent momentum <u(i)u(i)> and heat (u(i)theta) fluxes are obtained from completely explicit models of "gradient diffusion." The three-parameter model minimizes both the complexity of describing turbulent transport in a stably stratified medium and the costs For the numerical implementation of the model. The results of modeling the turbulent structure of penetrative convection over a heat island under the conditions of a calm and stably stratified atmosphere are presented, These results show that the three-parameter model of turbulent momentum and heat transport, in combination with an explicit algebraic model for turbulent stresses (normal and tangential) and for the vector of turbulent heat flux, makes it possible to calculate the heat-island-induced circulation, the distributions of the average temperature, and the rms fluctuations of the turbulent velocity and temperature fields. The calculated results are in good agreement with measured data.