Numerical experiments on the dynamics of the cloud-environment interface: small cumulus in a shear-free environment

The current paper extends the work of Klaassen and Clark. Serious numerical errors associated with the finite-difference approximations to the conservation laws for the thermodynamic variables were identified. These errors led to an unrealistic supersaturation field (or condensation rate field) near cloud edges. To avoid these numerical artifacts, the prognostic conservation equation for the water vapor mixing ratio was replaced by the appropriate prognostic equation for the supersaturation (which lead to a diagnostic treatment for the water vapor) and refined numerical techniques were used. The experiments reported in this paper were performed using both prognostic and diagnostic approaches for water vapor. Each of these was used with bulk and detailed microphysics. -from Author