乌海市雾预报指标分析

Technical Analysis of Forecasting Fog in Wuhai City

使用2005—2017年乌海机场逐时能见度资料,国家一般气象站逐时相对湿度、风速、气温等气象要素及逐日天气现象资料;分析了乌海市雾的环流特征,气象要素变化,提炼出了预报指标。结果表明:(1)引起乌海市雾的高空系统有西北气流型、偏西气流型、西南气流型等3类环流型,主要以西北气流型为主。(2)雾出现时大气环流形势弱,有增湿条件,存在逆温层,但逆温强度较弱。(3)雾出现在近地层水汽丰富,中层相对干燥的稳定大气层结下。(4)地面相对湿度≥90%,地面风速<3.0 m·s-1,气温日较差在9~16℃之间是雾发生的有利条件。

Using the hourly visibility data of Wuhai Airport from 2005 to 2017, the National General Meteorological Station including the hourly relative humidity, wind speed, temperature and other meteorological elements and daily weather phenomena datas, analyze the fog circulation and meteorological elements in Wuhai City and refined forecast indicators. The results show that:(1) The high-altitude systems that cause fog in Wuhai include three types of circulation patterns: northwest, west, and southwest, mainly northwest.(2) When the fog appears, the atmospheric circulation situation is weak with humidification conditions. there is an inversion layer, but the inversion temperature intensity is weak.(3) Fog appears in a stable atmospheric layer that is rich in water vapor near the surface and relatively dry in the middle layer.(4) The relative humidity on the ground is greater than 90%, the wind speed on the ground is less than 3.0 m·s-1, and the daily temperature difference between 9 and 16℃, which are favorable conditions for fog occurrence.