台风“Chanchu”变性过程位涡及锋生特征分析  

Characteristic analysis of potential vorticity and frontogenesis of extratropical transition for typhoon “Chanchu”

作　　者：廖玥 王咏青[1,2] 张秀年 LIAO Yue;WANG Yongqing;ZHANG Xiunian(Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory of eteorological Disaster,Ministry of Education/School of Atmospheric Sciences,Nanjing University of Information Science & Technology,Nanjing 210044,China;Nanjing Joint Center of Atmospheric Research,Nanjing 210009,China;Yunnan Meteorological Observatory,Kunming 650034,China)

机构地区：[1]南京信息工程大学气象灾害预报预警与评估协同创新中心/气象灾害教育部重点实验室/大气科学学院,南京210044 [2]南京大气科学联合研究中心,南京210009 [3]云南省气象台,昆明650034

出　　处：《气象科学》2019年第1期12-22,共11页Journal of the Meteorological Sciences

基　　金：国家自然科学基金资助项目(41875070;41530427;41275002);云南省重点研发计划-社会发展项目(2018BC007);北极阁开放研究基金-南京大气科学联合研究中心(NJCAR2018MS02);江苏省"333高层次人才培养工程"

摘　　要：利用非静力中尺度WRF模式输出的0601号"Chanchu"台风模拟资料分析了台风变性过程中的结构演变特征,并从位涡的角度,利用湿位涡方程对"Chanchu"变性过程中强度减弱但却能引发强风暴雨的原因进行了探讨。分析表明:台风在变性过程中,尺度逐渐增大并与东移南下的高空槽不断接近,在与高空槽相互作用之前,台风眼壁及外围雨带雷达回波减弱,最大风速减小,最大风速半径圈向外拓展;高低层位涡相接之后,由于高层正位涡的下传携带冷空气侵入台风,在低层锋区上诱发出气旋性环流,进而重新引发强对流,并在角动量的输送作用下,台风外围环流风速再次增大。变性后高空槽和台风在位相上仍有一定距离,高空槽仅与台风的外围环流相互作用,冷空气没有入侵台风内部,这是"Chanchu"没有重新加强的原因之一。利用锋生函数对引起锋生的各分量进行分析,结果显示非绝热加热是造成锋生的主要原因,散度和变形项的贡献次之,倾斜项对锋生几乎没有贡献。This paper uses data from numerical simulations of the non-hydrostatic mesoscale model WRF on typhoon“Chanchu”(0601)to investigate the structural evolution characteristics of Extratropical Transition(ET),and uses the moist potential vorticity equation to discuss why weakening typhoon“Chanchu”can still cause heavy storm during ET from the perspective of Potential Vorticity(PV).The analysis shows that”Chanchu”gradually expands and becomes nearly collocated with the upper trough upstream moving southeasterly.Before the interaction between trough and typhoon,the maximum wind speed decreases and RMW expands outward,accompanied by the reduction of radar reflectivity of eyewall and outer rain bands.After the upper-level and lower-level PVs meet,the cyclonic circulation is induced in the front area of the lower layer due to incursion of cold air associated with downward transportation of positive-PV from upper-level,and then the deep convection is retriggered.Under the transportation effect of the angular momentum,the wind speed of peripheral circulation of typhoon increases once again.After ET,there is still a certain distance in phase between the trough and typhoon.The upper trough only interacts with peripheral circulation of the typhoon and the cold air fails to intrude into the TC inner area,which is one of the reasons why“Chanchu”does not reintensify.The contribution of the four contributing terms to frontogenesis is analyzed based on frontogenesis function,the result shows that the diabatic heating term is the main contributor to frontogenesis,followed by the divergence and deformation terms,while the tilting term is negligible.

关 键 词：台风 变性 湿位涡 锋生函数 高空槽 

分 类 号：P444[天文地球—大气科学及气象学]