四川盆地大雾成因剖析

Causes of Heavy Fog in Sichuan Basin

为了构建“四川盆地大雾天气客观化预报系统”,采用天气学与统计学相结合的方法对四川盆地大雾天气的成因进行了剖析。分析表明,四川盆地多雾同四川盆地的地理环境所形成的近地层空气湿度大密切相关。形成四川盆地大雾天气的有利条件为:近地层层结稳定、近地层风力弱、近地层准饱和,大雾预报最为重要的是判断未来是否有降雨产生和辐射冷却强度。

In order to build the Objective Forecast System of Heavy Fog for Sichuan Basin, an analysis is made of the formation causes of heavy fogs over the Sichuan Basin by means of both synoptic and statistic methods. The results show that, fogs occur much more frequent in the Sichuan Basin than in other places, which is closely related to high humidity in the surface layer resulted from the geographic surroundings. The contributors to heavy fogs in the Sichuan Basin include stratification stability, weak wind, and quasi saturation in the surface layer. The key step to forecast heavy fogs is to determine the occurrence probability of rainfall and the intensity of radiation cooling.