EFFECTS CAUSED BY VARYING THE STRENGTH OF THE CAPPING INVERSION BASEDON A LARGE-EDDY SIMULATION-MODEL OF THE SHEAR-FREE CONVECTIVE BOUNDARY-LAYER

Effects caused by variation of the potential temperature lapse rate Ga mma in the free atmosphere are examined based on a ''large eddy simula tion'' model of the shear-free convective atmospheric boundary layer. The obtained results show that only near the top of the boundary layer are the statistical moments involving temperature strongly sensitive to changes of the parameter Gamma. Furthermore, the moments involving only the vertical velocity are practically independent of Gamma. The r atio R of the heat fluxes at the top and the bottom of the mixed layer increases when Gamma increases. For the values of Gamma from 1 to 10 K/km, typically observed in the atmosphere, the heat flux ratio R vari es in the range -0.2 to -0.3. When Gamma increases by an order of magn itude to 100 K/km, R increases only slightly to about -0.4. When Gamma decreases to zero, the heat flux H-i at the top of the mixed layer al so decreases to zero. In this case, the thermal structure of the atmos pheric boundary layer is found to be similar to nonpenetrative ''solid lid'' convection in a tank.