Wind characteristics of a strong typhoon

The wind characteristics of a strong typhoon (Typhoon Maemi 2003) are analyzed on the basis of 10 min wind speed samples. The wind speeds were measured simultaneously by nine vane and seven sonic anemometers at a height of about 15 m. Turbulence intensity and scale, gust factor, peak factor, decay factor of the coherence function, probability distribution function, power spectrum, and their variations with wind speed are obtained. Wind-direction-dependent analysis is conducted on the wind characteristics. Turbulence intensity decreases with wind speed and remain almost constant when the wind speed becomes high. The averaged values of gust factor and peak factor are 1.6 and 3.3, respectively. The spatial cross correlation and decay factor of the coherence function increase slightly with wind speed. The probability density function of fluctuating wind speed of a strong typhoon follows a Gaussian distribution, and the power spectrum of strong wind can be expressed by a Karman-type spectrum at the low frequency. The wind characteristics of this strong typhoon are shown to be very similar to those of non-typhoon winds. (C) 2008 Elsevier Ltd. All rights reserved.