乌鲁木齐国际机场2009年秋冬初雾天气的数值模拟分析

Numerical Simulation and Analysis of First Fog Weather over Urumqi International Airport in Fall/winter 2009

采用中尺度数值预报WRF(Weather Research Forecast)模式,以NECP的1°×1°全球再分析资料作为初始场资料,对2009年10月25日发生在北疆沿天山石河子—乌鲁木齐机场一带的罕见辐射雾天气进行数值模拟和诊断分析。结果表明,大雾出现前的低槽降水为近地层提供了充足的水汽来源,高空冷槽和地面冷高压的快速移出,使沿天山一带很快处于稳定的均压场控制下,有利于大雾天气的发生。在水汽条件以及天气形势具备的情况下,局地热力条件日变化特征导致的气温及风场的变化,是辐射雾发生的重要影响因素,它不仅决定着逆温层结的建立与破坏,还影响着局地水汽条件的变化,最终影响着雾的生消。

Based on NCEP 1°×1°global reanalyzed data as the initial field,we simulated and diagnosed a foggy weather that occurred on October 25th,2009 at Urumqi International Airport by using WRF（Weather Research Forecast） model.The result indicated that the small amount precipitation prior to the fog provided sufficient water vapor in the surface layer,and upper cold trough and surface cold high-pressure moved fast out of Xinjiang,which caused a stable uniform pressure field to control quickly the area along the Tianshan Mountains and was propitious to the fog weather occurrence.In the case of advantage of water vapor condition as well as the synoptic situation,the local thermodynamic condition caused the temperature and wind field change,which were the material effect factors for the radiation fog.These not only determined the creation and destruction of inversion stratification,but also influenced the changes in local water vapor condition,and ultimately affected the formation and dispersion of radiation fog.