中国东部云-降水对应关系的分析与模式评估

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

中文关键词:  云  降水  对应关系  模式评估

英文关键词:Clouds  Precipitation  Relationship  Model evaluation

中文摘要:

      为评估和改进模式中不同类型云与降水的对应关系,利用1998—2007年卫星-台站融合降水资料和国际卫星云气候计划的卫星观测云资料,采用诊断方法分析了中国东部季风区冬季层云、夏季对流云、层云与降水的水平分布及季节变化对应关系,并评估了BCC_AGCM模式的T42和T106分辨率版本对云-降水对应关系的模拟能力。观测资料分析结果表明,中国东部冬季云带和雨带都稳定少动,降水主要来自雨层云和高层云,南部沿海层云和层积云也对降水有贡献;夏季,中国东部表现为层积混合云降水特征,对流云带与降水带具有较好的对应关系,并具有一致的移动特征。对流降水主要来自深对流云和卷层云,深对流云云量和降水中心完全吻合,卷层云云带则表现出比深对流云主体和降水带偏北的现象;层云降水主要来自高层云和层积云。模式评估结果表明,中、低分辨率版本的BCC_AGCM模式均模拟出了冬季层云和稳定少动的降水带、夏季深对流云、卷层云和降水带的对应关系及随季风推进的移动特征。与T42模式版本相比,T106模式版本在夏季对流云云量的模拟及其与降水带的对应关系方面有所改善,说明改进的BCC_AGCM积云对流参数化方案与高分辨率模式网格更匹配,但冬季层云云量模拟误差变大,与降水带的对应关系变差,其原因值得进一步分析研究。

英文摘要:

      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.