11:00 AM - 11:15 AM
[AAS03-08] High-resolution numerical simulation of a waterspout observed over Okinawa, Japan on 5 March 2024
Keywords:Waterspout, Misocyclone, Numerical simulation
A waterspout occurred in Okinawa Prefecture, Japan on March 5, 2024. Based on the damage after it made landfall, the strength of the wind gust was estimated to be about 30 m s-1, which corresponds to the Japanese Enhanced Fujita (JEF) 0-scale. As doppler radar observations suggested that it was associated with a mesocyclone, the waterspout might be a tornadic waterspout. In this study, we conducted a numerical experiment with a horizontal resolution of 50 meters to investigate the detailed mechanism behind the waterspout. Although multiple misocyclones on the horizontal scale of 100 meters with vertical vorticity of the order of 10-1 s-1 were simulated, they show typical characteristics of a fair-weather waterspout (or non-tornadic waterspout) whose vertical vorticity is intensified through vorticity stretching with upward motion along a shear line without a mesocyclone. We will discusse why our experiment was not able to simulate the observed tornadic waterspout. We will also compare the characteristics of a vertical vortex simulated in a 250-m resolution experiment with that in the 50-m resolution experiment.