# Analysis of the Near-Ground Wind Field Characteristics during Typhoon Soulik
###### Abstract  
In 2013, during Typhoon Soulik, wind data were collected at various heights above the ground (15, 27, 53, 67, and 82 m) on the 550 kV 52# pole transmission tower in Ningde City, Fujian Province. The wind speed profile, turbulence intensity, gust factor, crest factor, and power spectrum were analyzed using 10 min interval wind speed records. The results show the following: (1) the average wind velocity of Typhoon Soulik varies in accordance with both the power law and the logarithmic law, but the Deaves-Harris model exhibits significant discrepancies; (2) the turbulence intensity in \(u\), \(v\), and \(w\) orientations decreases with the average wind velocity at each height. Exponential fitting is conducted on the strength of turbulence and gust factor profiles in each direction based on the standards of different countries, resulting in the derivation of empirical expressions; (3) the integral scale components of turbulence in \(u\), \(v\), and \(w\) orientations exhibit a positive correlation with both average wind velocity and height. The turbulence integral scale ratios in the longitudinal, transverse, and vertical directions at heights of 15, 53, and 82 m are 1:0.68:0.11, 1:0.67:0.27, and 1:0.67:0.30, respectively; (4) the [PERSON] empirical spectrum and the modified Kaimal cross-spectrum model closely match the observed wind power spectrum of Typhoon Soulik. The presented results contribute to furthering references for wind-resistant design of structures in typhoon-prone areas and prevention of typhoon-related disasters. type: 20  
and Rammasun. The result shows that the profile of the typhoons' winds departed from the power law to different extents. [PERSON] et al. [12] fitted the turbulence intensity profiles in front and behind the typhoon based on the measurement results of three anemometers at 10, 26, and 32 m above the anemometer tower and found that the fitting results had the smallest difference with Chinese standards. [PERSON] et al. [13] analyzed the data collected from four meteorological towers using mechanical anemometers to examine the gust characteristics of 10 typhoon winds near the ground. They discovered that the fitted turbulence intensity profiles closely matched the various standards. However, they observed a faster decline in the turbulence intensity above 40 m in the observation profiles. [PERSON] et al. [14] utilized a meteorological observation gradient tower that stood at a height of 365 m and examined the wind characteristics during the landing of the powerful Typhoon Hato. The researchers discovered that as the average wind velocity exceeded 10 m/s, the measured crest factor was notably lower than the predictions made by [PERSON] [15] and [PERSON] [16]. The reason for this disparity could be the non-gaussian characteristics of wind turbulence. [PERSON] et al. [17] used actual measured data from ultrasonic anemometers at 10, 80, and 100 m above the ground from a wind measurement tower in Fujian to analyze the wind profile of Typhoon Maria and found that index 0.2208 calculated by the power rate was greater than the Chinese standard value. In addition, numerous researchers have also examined wind characteristics, including the turbulence integral scale and wind speed power spectrum, utilizing data obtained from wind towers [18,19]. Wind load as a controlling factor for transmission towers is crucial for enhancing structural resistance against wind. Despite the fact that numerous researchers have extensively studied the field measurement of wind characteristics near ground, variations exist in the wind profiles, turbulence profiles, and peak factors derived from observed typhoons across different terrains and theoretical models. Meanwhile, due to the suddenness and uncertainty of typhoons, collecting typhoon data under field conditions is difficult, leading to a lack of research on the characteristics of near-ground wind fields in coastal areas in China. This study chose the 550 kV 52# pole transmission tower in Ningde City, Fujian Province as the observation base station.