积云对流参数化方案对大气含水量及降水的影响  

The Impacts of the Cumulus Convective Parameterization on the Atmospheric Water-Content and Rainfall Simulation in SAMIL

作　　者：刘屹岷[1] 刘琨[1] 吴国雄[1] 

机构地区：[1]中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京100029

出　　处：《大气科学》2007年第6期1201-1211,共11页Chinese Journal of Atmospheric Sciences

基　　金：国家重点基础研究发展规划项目2006CB403607;中国科学院团队国际合作伙伴计划"气候系统模式研发及应用研究";国家自然科学基金资助项目40475027;40221503;40575028;40523001;40675038

摘　　要：中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室所发展的高分辨率全球大气环流谱模式SAMIL,自从发展成R42L26新版本之后,显示出对全球气候基本态的模拟能力,但模式对流层低层以及热带地区整层偏干,且对热带地区的降水模拟存在"双赤道辐合带"这一普遍误差,在赤道地区以及北半球中纬度降水偏少,而在拉丁美洲降水偏多。敏感性试验表明这些误差是相互联系的。通过将700 hPa以下的相对湿度趋近于"观测资料"的试验显示模拟的降水误差减小了。据此,对Tiedtke积云对流参数化方案中的浅对流部分进行修改,增加了浅对流的侧向混合的卷入以及卷出率,并减小了对流方案中的云水-雨水的转换率,将其耦合到模式中。积分结果表明,修改后的方案明显改进了湿度和温度场的模拟,对降水的模拟能力有了很大的提高,基本消除了"双赤道辐合带"现象。The new version of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics （LASG/IAP） spectral atmospheric model SAMIL R42L26 has been developed and evaluated since 2005. The model shows its ability in representing the global climate, but it also suffers from some problems in simulating precipitation in the tropics, such as the double ITCZ in the central-western Pacific, less precipitation in the equator area and in the mid-latitudes of the Northern Hemisphere, and more in Latin America. These biases seem to result mainly from the treatment of subgrid scale convection, which is parameterized with the Tiedtke＇s mass flux scheme. A sensitivity experiment shows that these systematic errors are linked each other, and owe their existence mainly to the dry bias of the lower troposphere. In view of these results, several modifications are made to the Tiedtke＇s mass flux scheme used in SAMIL, and the results show apparent improvements in simulating the climate compared with the control experiment. In particular, the ＂double ITCZ＂ is eliminated and the modeled precipitation in the northern tropical area is more realistic. The modified scheme can also reduce both cold and dry biases in the middle troposphere. Results from the compared experiment show that the im- provements in the model performance mainly result from the improved shallow convection due to the introduction of the modified convective parameterization.

关 键 词：大气环流模式 积云对流参数化方案 质量通量方案 浅对流 

分 类 号：P426[天文地球—大气科学及气象学]