Abstract

Low-visibility weather poses a significant threat to aviation safety and operational efficiency. Lhasa Airport is situated in a high-altitude river valley region prone to dust events. Clarifying the characteristics and dominant factors of low-visibility weather is crucial for enhancing aviation meteorological support capabilities. This study systematically analyzed the weather types, spatiotemporal distribution characteristics, and key meteorological influencing factors of low-visibility events using ground-based automated meteorological observation data, monthly summary records, and wind lidar data from Lhasa Airport from January 2020 to July 2024. The results indicate that dust weather (blowing sand and floating dust) is the primary cause of low visibility, accounting for over 90% of low-visibility days. Low-visibility events exhibit significant monthly variations, with the longest cumulative duration occurring in January and February, while being extremely rare from July to November. Under low-visibility conditions, visibility levels are predominantly concentrated in the 3–4 km range (72.5%), and most events last less than one hour. Factor analysis reveals that north, easterly, and west winds are commonly associated with dust-induced low visibility. Wind speed demonstrates a significant negative correlation with visibility and serves as the primary driving factor. Moderate relative humidity is most conducive to maintaining visibility between 3 and 5 km. Case studies further confirm that sustained strong low-level winds (≥10 m/s), high surface wind speeds (≥7.5 m/s), and intense upward motion are the key dynamic conditions for triggering and maintaining dust-related low-visibility processes. This study presents, for the first time, quantitative thresholds for key meteorological parameters and their season-dependent characteristics for dust-induced low-visibility events at Lhasa Airport, and proposes actionable forecasting indicators. These findings offer clear practical implications for aviation meteorological services at high-altitude valley airports.

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