Influence of Complex Geomorphology on Low-Level Wind Shear at Airports on the Loess Plateau

Abstract Low-level wind shear (LLWS), characterized by sudden changes in wind speed/direction within 600 m off the ground, poses a significant risk to aviation safety. This study investigates the mechanisms of topographic features and land-use types influencing the formation of LLWS at Lanzhou Zhongchuan International Airport [International Civil Aviation Organization (ICAO): ZLLL], a representative high-altitude airport (1947 m MSL). Using a coupled Weather Research and Forecasting (WRF) Model–computational fluid dynamics (CFD) modeling framework for dynamic downscaling from mesoscale to microscale, systematic sensitivity experiments were conducted to quantify the effects of topographic elevation gradient and land-use type on the LLWS dynamics. Key findings include 1) simulations accurately reproduced LLWS evolution under northwest airflow conditions, with near-surface flow patterns primarily governed by convergence zones formed through interactions between opposing northwest and southeast winds. 2) Pronounced downward momentum transfer occurred along northwestern slopes, where turbulent transport emerged as the dominant mechanism for vertical momentum redistribution. 3) A shift from stable to near-surface unstable atmospheric stratification enhanced vertical momentum mixing, creating favorable conditions for LLWS development. 4) Terrain slopes modulated momentum descent and induced flow separation, generating microscale vortices strongly correlated with LLWS events; whereas land-use alterations spatially relocated convergence zones through modified surface roughness and thermal stability but exhibited negligible direct influence on microscale dynamics. These results underscore the interplay between topographic forcing and land-use heterogeneity in LLWS generation, offering insights for refining LLWS forecasting methodologies at high-altitude airports. Significance Statement This study deepens the understanding of dangerous low-level wind shear near airports by revealing how mountain terrain and land-use changes interact to cause sudden wind damage. Using advanced weather modeling, we show that terrain slopes accelerate winds, while surface features like vegetation or pavement alter wind patterns by modifying air mixing and heat exchange. These combined effects determine where and when hazardous wind shear occurs. Our findings highlight the need to consider both terrain and land-use characteristics in airport safety planning and wind prediction systems. By modeling how small-scale airflow interacts with regional weather, this work provides actionable insights into reducing aviation risks in complex landscapes, benefiting travelers and communities that depend on the safety of air transportation.