Validation of a stochastic radiative transfer model

A stochastic band model is used to investigate radiative transfer through broken cloud fields. The model was developed by Malvagi et al. (1993) and has been used to study the absorption of shortwave radiation (Byrne et al. 1996). The stochastic model distributes clouds in a clear sky according to the statistics of the cloud field and then calculates the ensemble-averaged radiation field. A one-dimensional shortwave radiation routine used in many modern general circulation models is used to evaluate the performance of the stochatic model. Numerical tests are performed to assess model sensitivity and to verify the realism of several parameters. Several days of observations of fair weather cumuli over Oklahoma are used to provide a description of the cloud field to the stochastic model and validate the output radiation field. The stochastic model appears promising in its ability to match observations.