Submitted to J. Climate

A methodology is described for testing the simulation of tropical convective clouds by models through comparison with observations of clouds and precipitation from Earth-orbiting satellites. Clouds are divided into categories that represent convective cores, moderately thick anvil clouds and thin high clouds, and fractional abundances of these clouds are computed as a function of rain rate. A three dimensional model is forced with steady forcing characteristic of tropical Pacific convective regions, and the model clouds are compared with satellite observations for the same regions. The model produces a good simulation of the relationship between the precipitation rate and optically thick cold clouds that represent convective cores. The data show large abundances of anvil cloud with a strong dependence on rain rate, but the model produces too little anvil cloud by a factor of about four and with a very weak dependence on rain rate. The observations show probability density functions for OLR and albedo with maxima that correspond to extended upper-level cold clouds, whereas the model does not. The sensitivity of the anvil cloud simulation to model parameters is explored using a two-dimensional model. Both cloud physical parameters and mean wind shear effects are investigated. The simulation of anvil cloud can be improved while maintaining a good simulation of optically thick cloud by adjusting the cloud physics parameters in the model to produce more ice cloud and less liquid water cloud.