Abstract: The micro-meteorological elements of an advection fog, which occurred in Feb 2006, were analyzed by using data from the Tianjin Meteorological Boundary Layer Tower The results show that temperature inversion and higher humidity are due to the warm and moist south-west advection, which provides the necessary conditions for the formation and maintaining of the advection fog The advection fog comes under the weak unstable condition There are double-inverse temperatures during the fog period with wind speed decreasing and wind direction shearing The fog dissipates from higher to lower layers with dry and cold air coming from the northwest associated with a cold front The long-lasting fog at lower layers is due to the subsidence inverse of cold air There is a close correlation between the characteristics of temperature profile and thickness of fog

Key words: advection fog, micro-meteorology, wind and temperature profile, low visibility

摘要： 利用天津255m大气边界层气象铁塔观测资料，分析了2006年2月平流雾天气过程塔层气象要素演变特征。结果表明：西南暖湿气流为平流雾的形成和长时间维持提供了逆温和湿度条件，平流雾形成前4个小时，西南暖湿气流突然增强。深厚平流雾形成时，低层大气呈弱不稳定层结；雾形成和发展期间，低层大气维持增湿和双层逆温层结，风场减弱，风向切变增强；冷空气产生的下沉逆温使低层雾得以维持较长时间，西北干冷空气的逐层入侵导致平流雾从高到低逐步消散；雾消散期间，雾体低层呈现出超绝热递减层结特征。分析还显示：平流雾过程中，温度廓线特征与雾体厚度关系密切。

关键词: 平流雾, 微气象学, 风温廓线, 低能见度