位涡塔结构及演变对飓风Wilma(2005)强度变化的影响  

The contribution of structure and evolution of potential vorticity tower to the intensity change of Hurricane Wilma(2005)

作　　者：刘爽[1] 钟玮[1] 刘继晨[1] 陆汉城[1] 

机构地区：[1]中国人民解放军理工大学气象海洋学院,南京211101

出　　处：《地球物理学报》2015年第5期1513-1525,共13页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41175054;41275002);国家自然科学基金重点项目(41230421)共同资助

摘　　要：本文利用高分辨率模式输出资料,对飓风Wilma(2005)不同发展阶段内位涡塔(Potential Vorticity Tower:PVT)的结构和演变进行诊断分析,并讨论位涡塔分布特征对飓风快速增强(Rapid Intensification:RI)过程的影响.研究结果表明,内核区域位涡的强度和结构变化主要取决于高层的暖心下传、中层的凝结潜热释放和低层的动力稳定性,而低层切向平均位涡的结构及其稳定性变化,对飓风快速增强的不同发展阶段具有很好的指示意义.飓风Wilma增强过程中,在高层增温、潜热释放和对流垂直混合作用下,PVT的结构出现单极位涡塔(Monopole PVT:MPVT)和中空位涡塔(Hollow PVT:HPVT)的相互转化,也造成了涡旋系统动力稳定性的变化.在实际个例中,重新定义位涡环的结构参数,即相对厚度和中空度,这两个参数能够表征系统的稳定性,将其在RI过程中的变化与飓风Wilma强度变化作相关性分析,表明结构参数能够表征PVT结构的不稳定性,且与飓风系统强度变化参数具有很好的相关性,结构参数与海平面气压变化率的相关性能够通过显著性检验.Observational studies and numerical models reveal that potential vorticity tower（PVT）and its outer PV bands correspond well with eyewall and spiral rainband in hurricanes.Thus,the PVT formation and evolution and its effect on hurricane intensity change have been explored as a new task in international hurricane research.In this study,high-resolution numerical model data is used to conduct dynamic diagnosis and correlation analysis.Dynamic diagnosis is conducted to depict the characteristics and evolution of the PVT in Hurricane Wilma（2005）.According to the correlation theory,the structural parameters that can be used to quantitatively describe the PVT structure are redefined and then applied into a real case study.This study aims to reveal the effect of the PVT structure and evolution on the rapid intensification（RI）of Hurricane Wilma（2005）.By comparing the change of physical variables associated with the PV and the intensitychange of Wilma,it is determined that the positive PV anomaly in the upper troposphere tends to occur during the pre-RI period. Moreover,the PV anomaly gradually weakens with the subsidence of upper-level warm core during the RI period and disappears at the post-RI period.The temporal evolution of the PV anomaly large centre in the middle and lower troposphere and the intensity change of Wilma are in phase.The appearance of the mid-level positive PV anomaly is closely related to the subsidence of upper tropospheric PV anomaly and the mid-level latent heat release associated with convective activity.Furthermore,the intensity change of the lower-level PV anomaly large centre satisfies the criterion of dynamic instability,which is the necessary condition for hurricane intensification.Thus,it can be seen that the PV intensity and structural change in the inner core of the hurricane mainly depends on the subsidence of the upper-level warm-core,the mid-level latent heat release and the low-level dynamic instability.Hence,the PV intensity and structural change in the inner core of th

关 键 词：热带气旋 位涡塔 强度变化 稳定性 

分 类 号：P445[天文地球—大气科学及气象学]