A new parametrization for the radiative properties of ice crystals: Comparison with existing schemes and impact in a GCM

A new parametrization of the single scattering properties of ice crystals suitable for use in general circulation models of the atmosphere is presented. The parametrization is developed from a recent treatment of the scattering properties of an ensemble of ice crystals, which has been validated against observational data and is based on a more rigorous treatment of ice optics than has been possible until recently. The new parametrization is compared with existing schemes in idealized test cases and its impact in a climate model is assessed.