乌鲁木齐机场一次高影响低云雾天气分析

Analysis of a High-Impact Low Cloud and Fog Weather Event at Urumqi Airport

摘要: 为揭示乌鲁木齐机场持续性浓雾的生消机理，为航空气象预报保障提供依据，利用高空地面常规观测、FY-4B新一代静止气象卫星、微波辐射计、跑道自动观测及地面加密自动气象站等多源资料，对2024年11月25~29日该机场一次持续浓雾过程的天气形势、生消机制及中低空气象要素特征开展诊断分析。结果表明：(1) 本次大雾形成于高空脊控制、低层存在明显暖平流、地面处于高压底后部的稳定环流背景下，为大雾长时间维持提供了有利的环流条件。(2) FY-4B卫星微物理合成图可有效监测大雾范围的演变过程与雾区厚度，弱下沉气流利于将降雪后的水汽约束在近地层，低层弱辐合与负涡度共同为大雾形成提供了动力与水汽支撑。(3) 北疆沿天山一带日落后的辐射降温助推盆地大范围雾区形成，机场大雾的生消与周边雾区强度、风场演变密切相关，偏南风和西南风利于雾的消散，贴地层降温幅度、逆温层强度及逆温层底高度对大雾强度与持续时间具有一定指示意义。

Abstract: To reveal the formation and dissipation mechanism of persistent dense fog at Urumqi Airport and provide a scientific basis for aviation weather forecast and support, this paper conducts a diagnostic analysis on the synoptic situation, formation-dissipation mechanism, and characteristics of middle-lower tropospheric meteorological elements of a persistent dense fog event at the airport from November 25 to 29, 2024. The analysis is based on multi-source data including conventional upper-air and surface observations, FY-4B new-generation geostationary meteorological satellite data, microwave radiometer measurements, runway automatic observation data, and observations from a dense network of automatic surface weather stations. The results are as follows: (1) The dense fog formed under a stable circulation background controlled by an upper-level ridge, with distinct warm advection in the lower troposphere and the surface located at the rear of the high-pressure base, which provided favorable circulation conditions for the long-duration maintenance of the fog. (2) The microphysical composite products of the FY-4B satellite can effectively monitor the evolution of fog coverage and the thickness of the fog layer. Weak large-scale subsidence helps confine post-snowfall water vapor within the surface layer, while weak convergence and negative vorticity in the lower layer jointly provide dynamic and water vapor conditions for fog formation. (3) Radiative cooling after sunset in the region along the Tianshan Mountains in northern Xinjiang facilitates the formation of large-scale fog areas in the basin. The formation and dissipation of dense fog at the airport are closely correlated with the intensity of surrounding fog areas and wind field evolution; southerly and southwesterly winds are conducive to fog dissipation. The cooling amplitude in the near-surface layer, the intensity of the inversion layer, and the base height of the inversion layer have certain indicative value for the intensity and duration of dense fog at the airport.