Large-Eddy Simulation and Parametrization of the Effects of Shear on Shallow Cumulus Convection

Large-eddy simulations are performed of ensembles of shallow convective clouds under varying shear. The scalar transports are shown to be largely unaffected by shear, while the momentum transport is strongly affected. The parametrization of the momentum fluxes is discussed. The cross-cloud pressure gradient, commonly neglected in shallow cumulus parametrizations, is shown to be a dominant term in the in-cloud momentum budget. The performance of two possible representations of this pressure gradient, each previously proposed for use in deep convection parametrizations, is assessed.