Analysis and model evaluation of the relationship between clouds and precipitation over eastern China

To evaluate and improve the correlation between the clouds and the precipitation in the models, the relationships of the horizontal distribution and seasonal variation between the various cloud types and the precipitation over eastern China are analyzed, and the model results simulated by T42 and T106 version of BCC_AGCM are evaluated respectively by using the ISCCP cloud data and the merged precipitation data from January 1998 to December 2007. It is found that over eastern China, the winter precipitation demonstrates stratiform features, the cloud belt and rain belt stably maintain near 27°N,and the precipitation is mainly resulted from Nimbostratus and Altostratus. On the other hand,the summer precipitation has both convective and stratiform characteristics. The summer convective cloud belt and rain belt move with the summer monsoon consistently. The convective precipitation is mainly resulted from deep convective clouds and Cirrostratus,with their maximum centers matching well with the precipitation regions, but Cirrostratus occurs in the north side of the main body of the deep convection and precipitation.The summer stratiform precipitation is mainly resulted from Altostratus and Stratocumulus. The model simulations show that BCC_AGCM has good skills on the cloud climate modeling. It can reproduce the correct location and stability of the winter stratiform clouds and precipitation, and also can reproduce the consistent evolution of the summer rain belt with deep convective cloud belts. Compared with the T42 model version,the summer precipitation and deep convective clouds, as well as their relationship simulated by T106 model are well improved. However,the winter stratiform clouds, precipitation and their relationship are worse.