9:30 AM - 9:45 AM
[AAS01-03] A Numerical Case Study on a Tornado that Formed in a Quasi Linear Convective System
A quadruple-nested simulation using Japanese Meteorological Agency non-hydrostatic model was performed. A simulation with horizontal scale of 2km successfully reproduced the QLCS, which propagated eastward quickly and reached around Chiyoda-town at 0830 JST. A cold pool and its associated downdrafts existed behind the convection region with strong updrafts (>10m/s). A simulation with the finest horizontal scale of 50m successfully reproduced the tornado in the QLCS. The vertical vorticity and horizontal velocity exceeded 0.7 s-1and 47m/s, respectively. At around 500m height, a low-level mesocyclone, which was accompanied by strong updrafts (>20m/s), formed and developed around the location of tornadogenesis. Near the surface, at 1 or 2 minutes before the tornadogenesis, strong rear-inflow jet (RIJ) accompanied by relatively cold air developed, and then tornado formed in the north of the RIJ. Thus, it is suggested that the RIJ play some roles in the formation and development of the tornado.