Analysis of characteristics and causes of strong winds in the Changsha-Zhuzhou-Xiangtan region and their impacts on low-altitude UAV flights

Accurate characterization of gale climatology is essential for ensuring the safety, route optimization, and risk early warning of low-altitude flight in the Changsha-Zhuzhou-Xiangtan (CZT) urban agglomeration. This study systematically analyzes the spatiotemporal characteristics of gales at different grades based on hourly maximum wind speed data from 525 surface stations and ERA5 reanalysis datasets in the region from 2016 to 2025. The K-means dynamic clustering algorithm is adopted to classify gale circulation patterns, and the corresponding formation mechanisms and their impacts on low-altitude aviation are further discussed. The results are shown as follows: (1) Gales of Grade 5 and above present distinct spatial heterogeneity, with an overall pattern of higher frequency in the north and lower frequency in the south. Northern Changsha is identified as the primary gale-prone area. (2) The circulations associated with Grade 5 and stronger gales are classified into six categories via K-means clustering, with significant seasonal differences in dominant synoptic systems. In spring and summer, the synergistic effects of baroclinic frontogenesis, peripheral circulations of the subtropical high, and terrain forcing produce prominent gale corridors over western Zhuzhou, northeastern Changsha, and the Xiangjiang River valley. In autumn, pre-typhoon squall line gales occur most frequently over the plains east of the Wuling and Xuefeng Mountains. In winter, gales induced by high-level cold advection are mainly distributed in the northwestern CZT region and the surrounding areas of the Green Heart Ecological Zone. (3) Diurnal variation analysis indicates that Grade 5-6 gales exhibit a single-peak and single-valley pattern, while Grade 7 and stronger gales show a double-peak and double-valley pattern, with spring and summer being the peak gale seasons. This study reveals the coupling mechanism between complex terrain and large-scale circulation in the urban agglomeration to regulate gale occurrence, providing new insights into gale forecasting. It also offers scientific support for low-altitude flight safety, route optimization, and operational risk warning in the CZT region.