MAINTAINABLE MECHANISM OF MESO-β SCALE CONVECTIVE SYSTEM  

作　　者：彭加毅 伍荣生 王元 

机构地区：[1]The Key Laboratory of Mesoscale Severe Weather.Department of Atmospheric Sciences,Nanjing University,Nanjing 210093 Department of Atmospheric Sciences.Nanjing Institute of Meteorology,Nanjing 210044 [2]The Key Laboratory of Mesoscale Severe Weather.Department of Atmospheric Sciences,Nanjing University,Nanjing 210093

出　　处：《Acta meteorologica Sinica》2002年第4期405-422,共18页

基　　金：This work was sponsored by Nanjing University Postdoctoral Foundation,the Science Foundation of Jiangsu Province Education Bureau(00KJB170001)and NSF of Jiangsu(BK99020),the State Key Basic Program:CHERES and the National Natural Science Foundation of Ch

摘　　要：By means of the Penn State-NCAR Mesoscale Model Version 5(MM5)with a horizontal resolution of 20 km.the maintainable mechanism of Meso-β scale Convective System(Mβ CS)has been investigated on the basis of simulation of the temporal and spatial thermodynamics structure of the MβCS which occurred in Wuhan and its surroundings on 21 July 1998.The occurrence of the significant warm-core in the center of the MβCS happened in Changjiang River Basin between the Mufu Mountain and the Dabie Mountain.To the southern side of the MβCS,there exist the southwest low-level jet(LLJ)and the vertical secondary circulation in the low and middle troposphere respectively.In respect to the northern of the MβCS,the northwest jet emerges in the upper troposphere,accompanied with cold and dry atmosphere downdrafts,resulting in another secondary circulation.The foregoing mentioned vertical wind shear provides a favorable dynamical environment for the intensification and maintenance of the MβCS.Equally important,the latent heat release associated with the MβCS produces the warm center in the middle troposphere and the pressure falls.The pressure drop then accelerates air parcels toward the low leading to strong convergence as well as the intensified convection,establishing a positive feedback between the convection and the latent heat release,which is the thermodynamic mechanism of the development and maintenance of the MβCS.By means of the Penn State-NCAR Mesoscale Model Version 5(MM5)with a horizontal resolution of 20 km.the maintainable mechanism of Meso-β scale Convective System(Mβ CS)has been investigated on the basis of simulation of the temporal and spatial thermodynamics structure of the MβCS which occurred in Wuhan and its surroundings on 21 July 1998.The occurrence of the significant warm-core in the center of the MβCS happened in Changjiang River Basin between the Mufu Mountain and the Dabie Mountain.To the southern side of the MβCS,there exist the southwest low-level jet(LLJ)and the vertical secondary circulation in the low and middle troposphere respectively.In respect to the northern of the MβCS,the northwest jet emerges in the upper troposphere,accompanied with cold and dry atmosphere downdrafts,resulting in another secondary circulation.The foregoing mentioned vertical wind shear provides a favorable dynamical environment for the intensification and maintenance of the MβCS.Equally important,the latent heat release associated with the MβCS produces the warm center in the middle troposphere and the pressure falls.The pressure drop then accelerates air parcels toward the low leading to strong convergence as well as the intensified convection,establishing a positive feedback between the convection and the latent heat release,which is the thermodynamic mechanism of the development and maintenance of the MβCS.

关 键 词：meso-β scale convective system(MβCS) warm center structure maintainable mechanism 

分 类 号：P458.121.1[天文地球—大气科学及气象学]