Observation and model study of cloud microphysics and weather regime classification

Using multiple information from cloud profiling radar and lidar collected mainly from ship observation in the past, reproducibility of ice cloud microphysics in the Center for Climate System Research–National Institute for Environmental Studies–Frontier Research Center for Global Change atmospheric general circulation model (AGCM) was investigated. The comparison was carried out utilizing the weather regime classification classified by International Satellite Cloud Climatology Project (ISCCP) cluster analysis, where the ice clouds properties (e.g., ice water path, precipitating ice fraction, cloud top height) retrieved from the radar/lidar observation was found to have rough consistency with what would be expected from such cloud-type mixture classification. The comparison result showed that the model tended to produce two times larger high cloud fraction in the cirrus regimes but 50% lower in the deepest convective regime. Despite the weather regime, the simulated IWP generally underestimated the observed values and the observed variety was weakly reproduced in the model. This was considered to arise mainly from the too small simulated IWC above 11km. In case of ice particle size (reff), the AGCM successfully predicted the observed frequency distribution above 11km, but however produced large overestimation below 11km due to too large fraction of reff around 100μm. The same dataset was further used to explore the uncertainty of the extended version of the retrieval algorithm used in this study for application to space-borne radar/lidar observations and to extend the study here to more global analysis of cloud microphysics.