Evaluating a stochastic shortwave radiation routine using a single-column model

The stochastic approach to modeling shortwave radiative transfer through a cloudy layer that has large-scale inhomogeneities in cloud properties (e.g., cloud size and spacing) allows for a more physically real cloud scene without huge computational expense. We are developing an empirical stochastic cloud-radiation parameterization from numerous stand-alone calculations that can be used in modern atmospheric general circulation models. The stand-alone model performs well in predicting downwelling shortwave fluxes at the surface when evaluated using independent observations for low, broken cloud fields have low liquid water paths and cloud fraction between 0.2 and 0.8. Results from coupling of the SIO single-column model with the stochastic model will be shown and compare with the new cloud-radiation parameterization.