Case Studies on the Characteristics of the Coastal Wind Profiles of Three Typhoons Landing along East China

Characteristics of wind profiles were studied using the Global Positioning System (GPS) sonde data from typhoons Wipha in 2007, Morakot in 2009, Fanapi in 2010, and Muifa in 2011. The gradient wind speed and corresponding level were first obtained. The wind profiles were then fitted by the power law and the logarithmic law. The exponential index, the ratio between the wind speed at 10 m and the gradient wind speed, and the height of the constant flux layer defined by the logarithmic law were further calculated. The possible difference between the gradient wind level and the height of the constant flux layer was investigated. The results show an obvious difference between the height of the constant flux layer and the gradient wind level for the typhoons landing along East China. Moreover, the parameters of the mean wind profiles from the typhoons were calculated, and the reason for the deviation of the wind profile below the gradient wind level from the logarithmic law was discussed.