Comparisons of Simulated Convective Clouds between a 1D Cloud Model and the WRF Model

An explicit 1D time-dependent tilting cloud model (ETTM), which consists of an updraft and a downdraft, was developed for potential use in cumulus parameterization schemes. The first step toward that goal is to evaluate the performance of the ETTM against 3D cloud model simulation results such as those from the Weather Research and Forecast (WRF) model. WRF is an appropriate choice here because it can be used as a cloud-resolving model, has the option of the Purdue Lin microphysics scheme that was used in the ETTM, and has a sub-grid-scale turbulence scheme similar to that in the ETTM. Three soundings with high convective available potential energy were chosen from three field experiments: Mesoscale Alpine Programme (MAP), International H2O Project (IHOP), and Rain In Cumulus over the Ocean (RICO). These soundings were used as initial conditions for both models. For each sounding, simulations with different radii of initial thermal bubbles were investigated. The depths of the updraft and the downdraft, extremes of vertical velocities, entrainment/detrainment rate, and the vertical profiles of mass and heat fluxes from the ETTM were analyzed and compared with those from WRF. The performance of the ETTM was quite reasonable and it will be further improved using simulation results from the WRF cloud-resolving model in the near future.