The effects of nonhomogeneous surface fluxes on the convective boundary layer: a case study using large-eddy simulation

Abstract

The inclusion of realistic size (450-900 m) and amplitude (~2 (°C)2 variance in surface temperature) non-homogeneities in a model of this resolution (50 m in the vertical, 150 m in the horizontal) does not in this case change the development of the mixed layer. The two runs show no significant differences in area-averaged statistics, possibly because of the nonzero wind which was present during the simulated afternoon. In the nonhomogeneous case, there is no evidence that thermals are anchored to or are preferentially forming over certain surface features, and there is no change in the thermal structure as evidenced by the power spectra of temperature, moisture, or vertical velocity. It appears that the use of horizontally homogeneous bottom boundary conditions is sufficient to adequately simulate the development of the boundary layer during combined free and forced convection. -from Authors