Large Eddy Simulation of Thermally Induced Oscillations in the Convective Boundary Layer

Mesoscale circulations induced by differential boundary layer heating due to surface inhomogeneities on scales of 5 km and more can significantly change the average properties and the structure of the convective boundary layer (CBL) as well as trigger off temporal oscillations. The results of one of the first numerical case studies using large eddy simulation (LES) on the mesoscale suggest that mesoscale circulations exhibit a considerably larger average kinetic energy than convection under homogeneous conditions. This affects turbulent transport processes and should be accounted for in larger-scale models even if their turbulence parameterizations rely on homogeneous control runs of high-resolution models.