Abstract:Using the observed multilayer near-surface wind data from the 350 m meteorological gradient observation iron tower in Shenzhen city, the variation characteristics of wind field and gust factor are analyzed during the landfalling of Typhoon Nida (1604) in August 2016. The results show that the near-surface wind speed at different heights presents the “M” pattern (increasing-decreasing-increasing-decreasing) with time, and the wind direction shifts from northwest to the south-southeast during the landing of the tropical cyclones. The wind speed increases with the increased height and the maximum vertical variation of the wind speed appears in the rear wind circle. In vertical direction, the wind direction is highly variable during the period from the front periphery to the front wind circle, while it remains almost unchanged with height during other periods. The vertical variation of wind speed follows logarithmic rule below 350 m during the periods of the front periphery, the front wind circle and the typhoon eye, while it only confirms to the same rule below 150 m during the periods of the rear periphery and the rear wind circle. During the landing of the Typhoon Nida, the roughness length observed from iron tower is about 0.52 m. Gust factor is decreased with the increased height, and its value is larger during the periods of the front periphery and the typhoon eye. Moreover, there is a negative correlation between gust factor and wind speed. The gust factor is decreased with increasing wind speed, especially when the wind speed is less than 10 m/s.