Vol. 18, issue 05-06, article # 13

Abstract:

Some results on modeled atmospheric boundary layer (ABL) structure above a thermally nonuniform surface (a heat island of limited size) are presented. To calculate the turbulent momentum and heat fluxes, the completely explicit algebraic models have been developed using the symbolic algebra from the transport equations in the approximation of weak-equilibrium turbulence. To provide for closure of the algebraic equations for turbulent fluxes, a three-parameter model of thermally stratified turbulence has been used. A two-dimensional computer test of a 24-hour ABL evolution shows that the third-order closure turbulence model (in Mellor and Yamada terminology) is capable of reconstructing the most important structure features of the ABL above the ground with a heat island, including those, which cannot be reconstructed with the k - e turbulence model. The results obtained well agree with the measurements and the numerical results of other authors.