| dc.description.abstract | During the TASSE(Taipei Summer Storm Experiment), a severe afternoon thunderstorm developed within Taipei basin on 22 July 2019, which produced intense rainfall in Daan Forest Park(max rainfall rate ~ 200mm hr-1) and caused urban-scale flooding. This study utilized IBM_VDRAS (Variational Doppler Radar Analysis System based on immersed boundary method), radar data, CWB weather station data and stormtracker data to analysis this case
At initial stage, sea breeze brought moist air into inland, and caused convection initiation at mountain region of Taipei, Taoyuan, Hsinchu. At developing stage, The environment was suitable for main convection developing because 1).Taipei basin was surrounded by scattered convection, the outflow of these convection converged with sea breeze and terrain, 2).sufficient mid-level water vapor and conditional unstable environment. At mature stage, the main convection initiated at center of Taipei basin and produced over 100mm accumulated precipitation within one hour, cell merge happened at this stage and increased the vertical velocity, extended the lifetime of this main convection, also caused a severe flooding in Daan Forest Park and its adjacent areas. At dissipation stage, land breeze happened, the divergence filed of Taipei basin center transformed from convergence to divergence, and new initiated convection propagated from Taipei basin to Taoyuan and Hsinchu.
This study also took advantage of IBM_VDRAS three-dimensional analysis to calculate the developing, mature and dissipation stage Q1, Q2 vertical profile, which could analyze the relationship between this afternoon thunderstorm case and environment. The result showed that Q1 had one peak pattern with max heating layer about 5km(575mb) on mature stage, Q2 had double peak pattern with low level max drying layer about 1.75km(824mb) and high level max drying layer about 5.25km(540mb) .
From the result we mentioned, by assimilating radar data, IBM_VDRAS is a very powerful ,useful system which can retrieve analysis well, and can help us to analyze the process of cell propagation , cell merge and other parameter quantitatively . | en_US |