RegCM3积云参数化方案对中国南方夏季强降水过程模拟的影响

Influences of Modeling the Summer Heavy Rain Process in Southern China Using Cumulus Convective Parameterization Schemes

利用区域气候模式RegCM3的最新并行版本,选择Anthes-Kuo、MIT-Emanuel和Grell 3种积云参数化方案,对2003年7月发生在淮河流域的强降水过程进行了多组模拟试验,重点分析比较了3种参数化方案对降水总量分布、主要降水时段和基本气象要素场的模拟能力,并相对实测降水和要素场进行了统计检验。对比分析试验结果,发现RegCM3对中国南方夏季强降水具有较好的模拟能力,不同参数化方案对中高层流场特征的模拟没有实质性差异。但对低层850 hPa流场结构(切变线、副高、低空急流、湿舌等)和水汽输送状况模拟存在一定差异,这也是它们能否正确模拟降水分布及过程、强度等特征的关键,也是Kuo方案降水模拟效果相对优于其他两种参数化方案的主要原因。

With the latest parallel version of regional climate model（RegCM3）,three different cumulus convective parameterization schemes,Anthes-Kuo,MIT-Emanuel and Grell,are used to test their capability in simulating the heavy rain process happened in Yangtze-Huaihe River valley in July 2003.The simulations were conducted on the monthly total amount,procedural amount and distributional pattern of precipitation,the wind,potential height and humidity field structure either in the lower or middle-upper atmosphere.By analyzing the model outputs,we obtained that RegCM3 is capable of simulating the basic three dimensional atmospheric structure in Southern China while the summer heavy rain happened.Based on present case study of July 2003,we found that Anthes-Kuo scheme is better than Grell and MIT-Emanuel scheme in simulating the amount,distributional pattern and procedural intensity of the precipitation.Secondly,according to the simulation appraising index of Ts and Bs calculated for different critical values on rainfalls,still,Anthes-Kuo Scheme is better than Grell and MIT-Emanuel scheme in simulating the most common precipitation events with total procedure amount less than 100 mm.For those extreme events with procedure rainfall larger than 100 mm caused mainly by sub-grid scale strong convective systems,the present model is unable to handle such systems because of the computational facility.The further research should be directed to raise model resolution or use model nesting techniques.Thirdly,the atmospheric structure in middle-upper levels（higher than 700 hPa） simulated by different cumulus convective parameterization schemes shows negligible differences,while in the lower atmosphere of 850 hPa both wind field and moisture transferring structure are different as different parameterization schemes being used,which interpreted why the simulated precipitation behaved differently and why Anthes-Kuo＇s scheme is better than the others.