| A new parameterization of the solar and infrared radiative properties of ice cloud which considers the multiple habits(hexagonal solid,hollow columns,hexagonal plates,bullet rosettes,aggregates and droxtals)of non-spherical ice particles has been developed.Effective radius is chosen as the parameterization factor from 30 ice crystal size distributions.Then new parameterization tables of 17 bands for the ice cloud module of BCC-RAD(Beijing Climate Center RADiative transfer model),including the band-averaged volume extinction/absorption coefficient,band-averaged asymmetry factor and band-averaged forward-peak factor were derived.The fitting formulae of bulk volume extinction coefficient,bulk single-scatter albedo,bulk asymmetry factor and bulk δ-function forward-peak factor for 65 wavelengths(0.20-99.99 μm)were built,which were more exact.Other parameterization schemes were also applied into BCC-RAD and their influences on radiation calculations are compared in 4 kinds of atmospheres,with maximum difference of approximately 30.0 W/m2 for radiative flux,4.0 K/d for heating rate.Additionally,a sensitivity test is performed to investigate the impact of ice crystal density on the radiation calculation by the three schemes.The results show that the maximum difference of radiative flux is 25.0 W/m2 and the maximum difference of heating rate is 4.5 K/d,which testifies ice crystal density exerts an important influence on the radiation calculation for cloudy atmosphere. |
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