拉萨贡嘎机场北风吹沙机制及激光测风雷达的应用

The Northern Wind-Driven Sand Mobilization Mechanism and the Application of Wind Lidar at Lhasa Gonggar Airport

摘要: 拉萨贡嘎机场地处雅鲁藏布江河谷，干季裸露的河滩沙源丰富，在强地面风作用下易形成低能见度吹沙天气。本文利用NCEP再分析资料和激光测风雷达产品，从高空形势、温压场配置和中低空风场特征方面，对2025年1月25日出现的一次北风吹沙天气进行了分析，结果表明：本次北风吹沙过程与冷空气活动有关，冷空气先在高原北部堆积形成强冷高压，500 hPa横切变和600 hPa横槽南压引导主体冷空气向东南垮塌，部分冷空气南下侵入拉萨地区。拉萨地区所在的高原中东部均受冷平流控制。DBS风廓线产品显示偏北风具有底层触发–向低层扩展、地面风增强–向中层扩展、地面风减弱的特点，底层偏北风触发初期有强下沉运动配合，持续的下沉气流有利于北风低空急流的维持。RHI (180˚)剖面产品能够跟踪北风层的推进和演变。实践表明激光测风雷达产品能够辅助判断中低层天气系统的精细化过境时间。此项工作对探究北风吹沙机制、拓展激光测风雷达在高原地区的应用场景和提升精细化预报预警水平具有重要意义。

Abstract: Located in the Yarlung Zangbo River Valley, Lhasa Gonggar Airport frequently experiences low-visibility sand-blowing weather during dry seasons due to abundant riverbed sand sources and strong surface winds. This study investigates a northern wind-driven sand mobilization on January 25, 2025, using NCEP reanalysis data and wind lidar products. The results show that: the sandstorm was linked to cold air activity, and cold air initially accumulated in the northern plateau, forming a strong cold high-pressure system. A 500 hPa transverse shear line and a 600 hPa horizontal trough guided the main cold air mass to collapse southeastward, with partial intrusion into the Lhasa region. Cold advection dominated the mid-eastern plateau, including the Lhasa area. DBS wind profile data revealed a three-stage northerly wind evolution: Surface-triggered northerly winds expanding downward; Enhanced surface winds propagating upward; Gradual weakening of surface winds. Strong downdrafts during the initial phase supported the maintenance of a low-level northerly jet. RHI (180˚) vertical section products effectively tracked the progression and evolution of northerly wind layers. Wind lidar data improved the precision of judging mid-low-level weather system transit times. This study advances understanding of northern wind sandstorm mechanisms, expands wind lidar applications in high-plateau regions, and enhances refined forecasting capabilities.