The features of cloud overlapping in Eastern Asia and their effect on cloud radiative forcing  

作　　者：ZHANG Hua PENG Jie JING XianWen LI JiangNan 

机构地区：[1]Laboratory for Climate Studies of CMA, National Climate Center [2]Nanjing University of Information Science and Technology [3]Chinese Academy of Meteorological Sciences [4]Canadian Center for Climate Modeling and Analysis, University of Victoria

出　　处：《Science China Earth Sciences》2013年第5期737-747,共11页中国科学（地球科学英文版）

基　　金：supported by National Basic Research Program of China (Grant No. 2011CB403405);National Natural Science Foundation of China (Grant No. 41075056);Public Meteorology Special Foundation of MOST (Grant No. GYHY201106022)

摘　　要：Characteristics of cloud overlap over Eastern Asia are analyzed using a threeyear dataset （20072009） from the cloud observing satellite CloudSat. Decorrelation depth Lis retrieved, which represents cloud overlap characteristics in the simulation of cloudradiation processes in global climate models. Results show that values of L in six study regions are generally within the range 03 km. By categorizing L according to cloud amount in subregions, peak L appears near subregions with cloud amount between 0.6 and 0.8. Average L is 2.5 km. L at higher altitudes is generally larger than at lower lati tudes. Seasonal variations of L are also clearly demonstrated. The sensitivity of cloud radiative forcing （CRF） to L;y in Community Atmosphere Model 3.0 of the National Center for Atmospheric Research （CAM3/NCAR） is analyzed. The result shows that L can have a big impact on simulation of CRF, especially in major monsoon regions and the MidEastern Pacif ic, where the difference in CRF can reach 4050 W m2. Therefore, accurate parameterization of cloud vertical overlap struc ture is important to CRF simulation and its feedback to climate.Characteristics of cloud overlap over Eastern Asia are analyzed using a three-year dataset (2007-2009) from the cloud observing satellite CloudSat. Decorrelation depth Lcf* is retrieved, which represents cloud overlap characteristics in the simulation of cloud-radiation processes in global climate models. Results show that values of Lcf* in six study regions are generally within the range 0-3 km. By categorizing Lcf* according to cloud amount in subregions, peak Lcf* appears near subregions with cloud amount between 0.6 and 0.8. Average Lcf* is 2.5 km. Lcf* at higher altitudes is generally larger than at lower latitudes. Seasonal variations of Lcf* are also clearly demonstrated. The sensitivity of cloud radiative forcing (CRF) to Lcf* in Community Atmosphere Model 3.0 of the National Center for Atmospheric Research (CAM3/NCAR) is analyzed. The result shows that Lcf* can have a big impact on simulation of CRF, especially in major monsoon regions and the Mid-Eastern Pacific, where the difference in CRF can reach 40-50 W m2 . Therefore, accurate parameterization of cloud vertical overlap structure is important to CRF simulation and its feedback to climate.

关 键 词：cloud overlap hypothesis decorrelation depth CLOUDSAT stochastic cloud generator （SCG） cloud radiation 

分 类 号：P422[天文地球—大气科学及气象学] S277.525[农业科学—农业水土工程]