A study on fluctuating wind characteristics during strong wind processes in the surface layer over the Qinghai-Tibet Plateau, Xizang region

To address the insufficient research on near-surface gale fluctuation characteristics in the Qinghai-Tibet Plateau, Xizang Automous Region, China (hereafter "Xizang Plateau"), this study utilizes ultrasonic anemometer data from two stations, Langkazi and Shiquanhe. Wind samples with a 10-minute average wind speed exceeding 8 m/s are selected. Based on statistical analysis, the fluctuating wind characteristics under type B terrain conditions (wide-valley lake basin and valley terrain) in the Xizang Plateau are investigated. The results show that the average turbulence intensities in the along-wind and across-wind directions are 0.23 and 0.21, respectively, and the average gust factors are 1.52 and 0.45, respectively. The overall fluctuation intensity is lower than that in coastal typhoon areas. The along-wind turbulence intensity and gust factor are close to the recommended values of the ASCE 7-22 of the United States. The average integral length scales in the along-wind and across-wind directions are 111 m and 113 m, respectively, with the along-wind integral length scale being closer to the recommended value of the AIJ-RLB-2004. The power spectrum of along-wind fluctuating wind speed shows the highest consistency with the von Kármán spectrum. Furthermore, a modified model for the relationship between gust factor and turbulence intensity applicable to such terrain areas is proposed to investigate the evolution laws of the fluctuating wind. The results show that, within the dominant inflow direction range, turbulence intensity and gust factor significantly decrease with increasing wind speed, while the integral length scale exhibits a clear directional dependence. Overall, the fluctuating wind parameters under type B terrain conditions in the Xizang Plateau show distinct regional characteristics. The findings can serve as a reference for wind-resistant design of building structures in such regions.