β效应和垂直切变对台风非对称结构及眼墙替换的影响  

Role of β-Effect and Vertical Wind Shear on Tropical Cyclone Asymmetry Structure and Eyewall Replacement

作　　者：陈国民[1,2] 沈新勇[1,3] 杨宇红 

机构地区：[1]南京信息工程大学气象灾害省部共建教育部重点实验室,江苏南京210044 [2]中国气象局上海台风研究所,上海200030 [3]马里兰大学大气海洋科学系,美国马里兰20742 [4]南宁市气象局,广西南宁530022

出　　处：《高原气象》2010年第6期1474-1484,共11页Plateau Meteorology

基　　金：国家重点基础研究发展规划973项目(2009CB421503);国家自然科学基金项目(40775033);公益性行业科研专项经费项目(GYHY200806009);江苏省青蓝工程(2009);广西区气象局重点项目"南宁市九十年代以来致灾暴雨过程研究"共同资助

摘　　要：利用一个完全可压、非静力及原始方程热带气旋模式(TCM4),通过对f平面和β平面中不同强度的垂直风切变下理想热带气旋的模拟,研究了β效应和垂直风切变对热带气旋强度和结构的影响。结果表明:(1)理想气旋植入相对较弱的垂直风切变之后其强度最终将会进入一种近似常定状态,通过研究这种准常定状态对切变强度的敏感性发现,研究垂直风切变对理想气旋影响,应该讨论理想气旋能否维持在一个特定强度(台风、热带风暴及热带低压等)的极限垂直切变,而不是去讨论决定理想气旋将减弱还是增强的极限垂直风切变值;(2)在f平面下,由于垂直风切变造成涡度平流随高度变化,使得在顺切变前部以及左侧边界层附近产生辐合,伴随着空气的气旋式螺旋上升,外流层对应区域产生辐散,从而使得强对流和强降水发生在顺切变左侧。(3)行星涡度梯度(β效应)也能使涡旋产生一定的非对称性。当考虑β效应和垂直风切变的双重叠加效应时,所产生的非对称性比单纯由β效应或垂直风切变产生的非对称性更大,并且强对流区主要集中在顺切变左前部。(4)热带气旋眼墙替换过程或许可以被预测,因为它们似乎与β效应和环境流(VWS)存在联系。A long-standing issue on the role of vertical shear and β-effect on tropical cyclone intensity and structure is studied through a series of numerical experiments under different vertical wind shears（VWS） in f-and β-planes using the fully compressible,nonhydrostatic tropical cyclone model-TCM4.The result shows that：（1） When a TC is embedded in a relatively week VWS,the intensity of this TC will finally become a steady-state,by researching the sensitivity of the steady-state intensity to the VWS,we suggest that it may be more appropriate to discuss the threshold of a VWS for a TC to stay above a certain intensity（typhoon,tropical storm and tropical depression） instead of a threshold to determine whether a TC would weaken or intensify under a VWS.（2） In f-plane,the vorticity advection are changed with height caused by vertical shear,which in turn produces low-level convergence ahead of and to the left of the shear vector,with the air then rising in a cyclonic spiral,correspond to this,the outflow level exist a divergence region,producing convection and rain on the downshear left.（3） Planetary vorticity gradient（β-effect） could also cause a certain asymmetric,when considering the superposition effect of β-effect and VWS,the asymmetric is more than it cause individual by β-effect or VWS,and the severe convection concentrate on the left front of the shear vector.（4） The eyewall replacement phenomena may have a certain degree of predictability because they appear to depend on the β-effect and VWS.

关 键 词：TCM4模式 垂直风切变 非对称 眼墙替换 

分 类 号：P425[天文地球—大气科学及气象学]