Doppler Wind Lidar Observations of Wind Shear Associated with Low-Level Jets in a Valley Terrain

Low-level wind shear (LLWS) poses a critical threat to aviation safety, especially at high-altitude airports located in valley environments. However, the formation mechanisms of LLWS with low-level jets (LLJs) remain poorly understood under high-altitude valley conditions. In this study, high-resolution Doppler lidar observations collected during March–April 2024 were used to investigate the characteristics of low-level wind fields, LLJs, and LLWS, as well as their relationship in an airport environment. The results reveal pronounced diurnal variations in the low-level circulation, with easterly winds dominating from early morning to late morning, westerly winds prevailing in the afternoon, and southerly winds occurring at night. LLJ events exhibit a strong diurnal cycle, with the highest frequency occurring during 02:00–10:00 LT, and jet cores are mainly distributed between 200 and 300 m. The observed LLJs are predominantly easterly, with typical maximum wind speeds of 8–10 m s−1. The development of LLJs is related to enhanced LLWS, although the temporal correspondence between LLJ intensity and LLWS evolution varies among individual events. The vertical shear structure is closely related to LLJ characteristics, including jet core height and wind speed distribution. Case analyses further demonstrate that the spatial evolution of LLWS follows the directional migration of LLJs, with the high wind-speed region shifting from easterly sectors in the morning to westerly sectors in the afternoon and southerly sectors at night. These findings provide new observational insights into LLJ-related LLWS processes under high-altitude valley environments and contribute to improved understanding of low-level wind hazards in complex airport environments.