The Impacts of Ice Cloud Optical Property Parameterizations on Simulated Short-Term Climate States

The representation of ice cloud optical properties in climate models has long been a difficult problem. Very different ice cloud optical property parameterization schemes are used in various models based on very different assumptions of ice habits, particle size distributions, and surface roughness conditions. It is not clear as to how simulated cloud radiative effects and climate variables are affected by the ice cloud optical property parameterizations. Five ice cloud optical property parameterization schemes, including three based on ice habit mixtures suitable for general ice clouds, mid-latitude synoptic ice clouds, and tropical deep convective ice clouds, and two based on common single ice habits, are developed under a same framework and implemented in the AGCM. The differences in the simulated shortwave and longwave cloud radiative effects are firstly evaluated. Then the corresponding changes in simulated climate states are discussed. The goal of this study is to quantify the impacts of various factors to ice cloud optical property parameterizations on climate simulations.