Parametrization of effective sizes of cirrus-cloud particles and its verification against observations

A simplified parametrization of effective sizes of cirrus-cloud particles is developed in terms of the ice-water content and the cloud temperature based on some earlier studies. The effective particle sizes of the cirrus clouds determined using the simplified parametrization are compared with the results determined from observations. The results are generally encouraging. The simplified parametrization is further tested by incorporating it into a new ice-cloud optical-property parametrization scheme and performing radiative-transfer calculations. The results show that this scheme in conjunction with the ice-cloud optical-properties scheme can generate a reasonably good estimate of cirrus-cloud radiative properties compared with the observations.