Treatment of ice clouds in photolysis
In the photolysis routine, the extinction for ice particles is calculated based on Eq. (3.9a) from Fu (J. Climate, 1996), using coefficients valid for wavelengths between 330 and 360 nm. The corresponding formulas for the single-scattering albedo and the asymmetry factor are not used in the TM5 code. These are set to the values obtained for liquid water clouds, which are calculated based on Slingo (JAS, 1989) for wavelengths 250-690 nm. Moreover, the effect of the ice clouds on photolysis rates is not included if the liquid water content is close to zero.
Just wondering, why don't we calculate the ice optical properties and do a proper averaging?