2022年冬季乌鲁木齐机场三场高影响大雾天气过程对比分析

Comparative Analysis of Three High-Impact Foggy Weather Processes at Urumqi Airport in Winter 2022

摘要: 本文基于1˚ × 1˚的NECP再分析资料、气象自动观测系统(AWOS)、微波辐射计等观测资料，对乌鲁木齐机场2022年冬季三场高影响大雾天气过程的环流背景、边界层内气象要素及相关物理量的分布特征进行了对比分析。结论表明：1) 本文大雾个例具有低温低湿的特点，浓雾区的水平尺度较小，分布极不均匀。2) 所选个例的环流背景有利于大雾的发生。过程一与过程二为暖脊型，过程三则为槽前型。大雾发生前的降雪对近地面层的增湿作用也不可忽视。3) 贴地层气温偏低，且气温升降均伴随着RVR降低，表明贴地层的辐射降温并非是造成大雾的唯一原因。贴地层相对湿度均不足90%，表明大雾发生时的水汽条件一般。4) 大雾发生与维持时，地面多为静风或微风。若风向频繁出现偏东风及偏西风的转换，浓雾区会随之移动，表现为跑道两端RVR频繁波动，变化幅度大。5) 逆温层是大雾发生维持的必要条件，适宜的逆温层顶高度与较强的逆温层有利于大雾的发生维持，逆温层减弱或逆温层抬升形成脱地逆温层时，大雾常常结束。6) 贴地层气象要素受下垫面影响较大，气象要素与大雾的相关性难以确定。边界层内气象要素的变化则与大雾有一定的联系。

Abstract: Based on 1˚ × 1˚ NECP reanalysis data, automated weather observing system (AWOS), microwave radiometer and other observation data, this paper compares and analyzes the circulation background, meteorological elements in the boundary layer and the distribution characteristics of related physical quantities of three high-impact fog weather processes in Urumqi Airport in winter 2022. The conclusion shows that: 1) The case of heavy fog in this article has the characteristics of low temperature and low humidity, and the horizontal scale of the dense fog area is small, with extremely uneven distribution. 2) The circulation background of the selected case is conducive to the occurrence of heavy fog. Process one and process two are warm ridge type, and process three is groove front type. The humidification effect of snowfall before the occurrence of heavy fog on the surface layer cannot be ignored. 3) The temperature in the surface layer is relatively low, and the temperature rise and fall are accompanied by a decrease in RVR, indicating that the radiation cooling in the surface layer is not the only cause of heavy fog. The relative humidity of the surface layer is less than 90%, indicating that the water vapor conditions during the occurrence of heavy fog are average. 4) When heavy fog occurs and is maintained, the ground is mostly calm or slightly windy. If there is a frequent transition between easterly and westerly winds in the wind direction, the dense fog area will move accordingly, manifested as frequent fluctuations in RVR at both ends of the runway, with a large amplitude of change. 5) The inversion layer is a necessary condition for the occurrence and maintenance of heavy fog. A suitable height of the inversion layer top and a strong inversion layer are conducive to the occurrence and maintenance of heavy fog. When the inversion layer weakens or rises to form a detached inversion layer, heavy fog often ends. 6) The meteorological elements in the surface layer are greatly affected by the underlying surface, and the correlation between meteorological elements and heavy fog is difficult to determine. The changes in meteorological elements within the boundary layer are somewhat related to heavy fog.