Study on the Characteristics of Regional Dense Fog in Chuzhou
Based on the conventional surface observations,radiosonde data,Fengyun-2 satellite cloud image and ERA5 reanalys-is data,the spatiotemporal distribution of regional radiation fog,advection fog and frontal fog,as well as the key meteorologi-cal characteristics at surface and high altitude in Chuzhou from 2005 to 2021 were statistically analyzed,in order to better un-derstand the basic characteristics and formation mechanisms of fog in Chuzhou.Meanwhile,the classification of dense fog was also discussed based on the weather patterns at both high and low altitude.The results showed that:1)The regional dense fog in Chuzhou occurred more in the west and less in the east and south,and happened more frequently from October to March but less from May to August.2)The dense fog was mainly divided into radiation fog,advection fog,and frontal fog.The tempera-ture inversion in the lower atmosphere was the necessary condition for fog formation.The fog formed under the 1 000 hPa rela-tive humidity of more than 80％,and the surface wind speed of generally smaller than 2.5 m/s.Radiation fog and advection fog both showed the characteristics of"dry up and wet down"in the lower atmosphere,which was not obvious for frontal fog.The 1 000 hPa wind speed for radiation fog was smaller than 4.0 m/s but greater than 4.0 m/s for advection fog,which varied wide-ly for frontal fog.3)For radiation fog,the 500 hPa weather patterns were divided into northwesterly,southwesterly and west-erly flow.The 850 hPa and its below layer presented an anticyclonic circulation,and at least one layer was affected by warm temperature ridge.The wind speed at boundary layer was small,and the surface was generally controlled by weak high pressure and uniform pressure field.For advection fog,the 925 hPa weather patterns were divided into front of low trough,back or bot-tom of high pressure,and top of warm shear.The surface was dominated by easterly wind(including southeasterly wind),and the wind was strong at some times.Moreover,a few samples were accompanied by weak precipitation.Frontal fog was mainly caused by cold front,warm front and stationary front systems,among which the cold front fog events accounted for 79％of the total frontal fog events,which primarily occurred in autumn and winter.
万方数据
维普
