Annual maximum wind speed distributions caused by typhoons for 40 years from 1950 are plotted on the extremal probability papers at 28 weather stations of JMA (Japan Meteorological Agency). Corresponding distributions which are estimated by a probabilistic procedure based on the statistical properties of typhoons such as central pressure difference and travelling speed are compared with previous ones by introducing conversion factors from the gradient wind to the surface one.
It may be said that so called indirect methods are convenient to avoid the effects due to not only increase of surface roughness in observation sites but also randomness of typhoons, since the both distributions seem to be nearly comparable.
Effects of super-gradient wind are also investigated by a simulation.
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