Turbulent wind characteristics in typhoon Hagupit based on field measurements

Abstract

Wind loads are the dominant loads for large-scale buildings and structures in tropical cyclone-prone regions; however, wind characteristics in tropical cyclones are still far from being understood. In this study, wind characteristics concerned in engineering applications, for example, wind attack angle, friction velocity, drag coefficient, turbulence intensity, integral scale, gust factor, and peak factor, were carefully investigated based on field measurements in typhoon Hagupit and were compared with measurements in typhoon Maemi and three hurricanes in literatures. The results show that drag coefficient increases with mean wind speeds at low levels and then decreases gradually at wind speed greater than 22.45 m/s in typhoon Hagupit over sea surface; turbulence intensities in front-side eyewall region are greater than those in back-side eyewall regions both in typhoons and hurricanes; the ratio between longitudinal integral scale and lateral integral scale, Lxu : Lxv, is scattered, but the ratio between longitudinal integral scale and vertical integral scale, Lxu : Lxw, is closer both in typhoons and hurricanes; the gust factor in typhoon Hagupit is 1.25 over open sea surface and 1.42 over open flat terrain; the peak factor is about 2.4.