侵台颱風路徑變化與快速發展之機制探討：平流層與對流層的位渦動力分析

This study will mainly employ the global model MPAS to simulate typhoonsaffecting Taiwan and conduct dynamic diagnostics (potential vorticity, angularmomentum and kinetic energy budget analyses) to understand the essentialfeatures of typhoon track and circulation evolution and the dynamic mechanismof rapid intensification (RI) associated with the typhoons and its influence on trackevolution. We will continue to investigate Typhoon Lekima (2019) to understandthe RI process prior to its northward deflection when approaching northernTaiwan and the influences of the Central Mountain Range (CMR) and the RI ontrack deflection. In the project of this year, we will also focus on the intensetyphoon Chanthu (2021) that took a sharp north turn when closing to thePhilippines with a developing RI and then moved northward offshore alongeastern Taiwan, by looking into the dynamic mechanisms of its induced shortterm RI and track turning as well as the influence of the CMR on the slightdeflection toward northern Taiwan at later stages. Previous studies mainlyemphasize on fast development of upper-tropospheric PV (UTPV) inside theeyewall that may trigger severe RI. However, our recent research reveals thattriggering of a severe RI in several supertyphoons indeed requires fastdevelopment of lower-stratospheric PV (LSPV) in coincidence with an intenseLSPV core near the eyewall, which through vertical PV advection to link withupper-eye dynamics may acts as one of important mechanisms in order tofacilitate an extension of the developed UTPV tongue in the upper eyewall alongthe upper-level outflow. In this study focusing on the two nearly super-intensetyphoons, we will concentrate to the relative roles of both LSPV and UTPV in RIand the dynamic processes of the induced RI, as well as compare the differencebetween their RI and the severe RI of other supertyp