Multi-Rotor UAV Observations of the Atmospheric Boundary Layer over Complex Terrain: Accuracy Validation and Dynamic Mechanisms of Flight Disturbances

Abstract. Unmanned aerial vehicle (UAV)-based sounding has become a flexible and cost-effective approach for probing the atmospheric boundary layer (ABL), yet its measurement credibility over complex terrain and the dynamic response of UAV flight attitude to boundary-layer dynamics remain insufficiently quantified. Here, we implement multi-rotor UAV field campaigns equipped with well-calibrated meteorological payloads, including co-located intercomparison observations against a 100-m gradient meteorological tower at the Xingtai Field Scientific Experiment Base, and vertical-profile surveys across the lower ABL over the eastern Taihang piedmont. The comparative observations demonstrate excellent agreement between UAV and tower measurements: vertical profiles of wind speed, wind direction, air temperature, and relative humidity exhibit strong correlations, negligible systematic biases, and coherent vertical structures. Stability parameters derived from high-frequency hovering observations, including potential temperature and gradient Richardson number (Ri), also closely match tower references, verifying the platform’s capability to reliably resolve ABL thermal stratification and dynamic stability. Three successive evening soundings capturing the transition from a convective to a stable boundary layer reveal that UAV attitude disturbances are strongly suppressed within stably stratified layers, but markedly amplified in near-neutral to weakly unstable layers where intense vertical wind shear coincides with weak thermal suppression, with the most severe perturbations occurring near the cloud base. The joint distribution of Ri and vertical wind shear further indicates that turbulence-induced flight bumpiness generally intensifies with increasing shear and peaks under unstable stratification, while a localized anomaly suggests possible resonance-like coupling between turbulent eddy scales and airframe dynamics. These findings establish a quantitative observational basis for reliable UAV-based ABL sensing and low-altitude flight-safety assessment over complex terrain.