Statistical characteristics of tropical-cyclone parameters and the risk assessment problem

A statistical method for long-term cyclone risk assessment is proposed. A t echnique for estimating the exceedance probabilities of the maximum wind sp eed V-max(T) at a given point over a time period T is developed. The techni que is based on the well-known relation between the wind speed V(R) and the distance R from the typhoon center to a given point: V(R) = V(max)root R-m ax/R, R greater than or equal to R-max, where R-max is the radius of the ty phoon's central part where a maximum wind speed at a given time is observed . The risk assessment method is applied to a catalog of typhoons occurring in the western Pacific during the period 1950-1988. The catalog lists 1013 events and provides maximum wind speeds every 12 hours. The maximum wind sp eeds exceeded over the time intervals T = 1, 2, 5, 10, and 20 years with pr obabilities of 0.5, 0.9, 0.95, and 0.99 are calculated for Vladivostok and Hong Kong. The method can be useful for designers, builders, insurance comp anies, and local authorities in regions subject to typhoons.