Wind-induced disaster

[23] Experiment of Environment of Tornadogenesis in Multifan Wind Tunnel

○Hiromori Miyagi¹, Koji Sassa² (1.Faculty of Engineering, Miyazaki University, 2.Science department, Science cluster, Kochi University)

Keywords:multifan wind tunnel, tornado, PIV

When the outer rainband of Typhoon 1408 passed above Kochi, two tornadoes occurred and caused damage. The present study aims to clarify the characteristics of the tornadoes and their parent cloud by analysing data obtained by JMA Doppler radar, two polarimetric radars in Kochi University and other observation data. We also made damage investigation. One of damaged areas was 8 km long. Its length is the longest in the other cases occurred in the Kochi plane for 20 years. We observed the gust front and mesocyclone in the parent cloud. But, these arrangement was different from that of ordinary supercell and vault was not observed. Then, the parent cloud was found to be a non-supercell. The dual-Doppler analysis showed that the tornadoes persisted under cyclonic wind shear. When the tornadoes landed, the vorticity was bigger and their diameter was smaller in the lower layer.