鲁西一次持续大雾过程分析

ANALYSIS OF A CONTINUATIVE FOG EVENT IN WESTERN SHANDONG PROVINCE

利用 NECP 资料和常规观测资料对2011年12月初鲁西持续大雾过程进行诊断分析，结果表明：本次大雾期间环流形势稳定少变，前期天气晴好，温度日较差大，辐射冷却作用强，以辐射雾为主；后期天气以阴或多云为主，辐射冷却作用弱，偏东风的作用使得雨区暖湿空气移动到冷下垫面上冷却形成雾，平流冷却作用强，以平流雾为主。诊断分析发现：上干暖下湿冷的边界层湿度条件；稳定的大气层结条件；充沛的暖湿水汽输送；低层（1000-900 hPa）较弱的上升运动都有利于大雾的发展和维持。当上升运动发展到整层一致且强盛时，湍流运动会阻碍大雾的发展。

Using the NECP reanalysis data and conventional observation datasets,the long -drawn fog in Dec 201 1 in western Shangdong province is analyzed.The results show that this dense fog maintained in the stable circulation position.It was radiation fog in the early stage for the heavy radiation cooling effect caused by low cloudiness and large diurnal temperature range.In the later stage the advection fog was the main one because the warm wet air was advected into clod underlying terrains under the influence of easterly winds,which brought about the heavy advective cooling effect.The cloudy weather weakened the radiation cooling effect.We achieved some conclusions after the diagnosis analysis that proper humidity conditions in the boundary layer,stable stratification condition,plentiful water vapor transport and weak upward motion of low -level （1 000 -900 hPa）are the main reasons of this dense fog.It will hinder the development of fog when the upward motions all markedly enhance from the lowest -level to highest.