热带气旋“Malakas”与中纬度系统的相互作用及其结构变化

The interaction of the tropical cyclone “Malakas” interaction with midlatitude flow and its structural change

本文利用中尺度数值模式WRF和LAGRANTO轨迹模式对2010年变性台风“Malakas”进行数值模拟和轨迹分析,分析了Malakas在变性过程中与中纬度系统的相互作用,以及在相互作用过程中Malakas的结构变化特征。结果表明:Malakas变性过程经历了三个阶段:(1)高层扰动加强期,高层的正位涡产生的气旋性环流使低层Malakas中心北部的斜压带西侧产生负的温度平流,表现为冷空气的入侵;(2)Malakas和中纬度系统相互作用时期,台风北上导致斜压带出现,深对流的爆发使低层暖湿气流沿着斜压带上升,快速上升气流中的潜热释放导致低PV空气向对流层上部净输送,在其北部高层重新构建出一个脊;(3)Malakas变性成温带气旋,残存的台风内核与斜压带逐渐合并,负的位涡平流带着非绝热外出流驱动了下游最初脊的构建,加速并且固定了中纬度急流,并整体放大了上层Rossby波模式。

In this paper,the WRF model and LAGRANTO trajectory model are used to carry out numerical simulation and trajectory analysis of typhoon Malakas(2010)during its extratropical transition,analyzing the impact of typhoon Malakas on the midlatitude flow and the structural change characteristics of Malakas during the interaction process.The analysis shows that Malakas has experienced three stages during its extratropical transition:(1)During the upper disturbance intensifying,the cyclonic circulation generated by high-level positive Potential Vorticity(PV)generates negative temperature advection on the west side of the baroclinic zone in the northern part of the Malakas center,which is manifested as the invasion of cold air.(2)During the TC-midlatitude flow interaction period,the typhoon heads northward and leads to the occurrence of the baroclinic zone.The deep convection eruption causes the low-level warm wet air to rise along the baroclinic zone,and the release of latent heat in rapidly ascending air leads to a net transport of low-PV air into the upper troposphere to rebuild a ridge in the part of north.(3)During the extratropical cyclone stage,the remnants of the TC inner core merges with the baroclinic zone.The negative PV advection by the diabatic driven outflow initiates ridge building,accelerates and anchors a midlatitude jet streak,and overall amplifies the upper-level Rossby wave pattern.