安顺大雾的环流分型及典型个例分析

Analysis on circulation pattern and typical examples of heavy fog in Anshun

该文利用1961—2010年安顺6个观测站的大雾观测资料、Micaps资料及NCEP1°×1°资料,采用天气学分型方法,对安顺区域性大雾根据其形成机制进行环流分型,划分为静止锋雾和辐散雾,并将静止锋雾划分为西部(西南部)和中部型,分别对3种环流型作出天气学概念模型,选取典型个例对不同类型大雾发生的动力和热力特征开展诊断分析,结果表明:西部(西南部)静止锋雾出现在静止锋稳定维持期间,主要是由于静止锋低层水汽抬升,中层下沉气流使水汽仅能在近地层较低的环境温度中凝结;中部静止锋雾出现时在南部往往有辐合切变,较强的暖湿平流出现在锋前,静止锋移动到贵州中部,形成机制不仅有静止锋的作用,还具有平流雾的特征;而辐射雾则整层为下沉气流,水汽饱和层很薄,由于下沉逆温使水汽集中于近地层,夜间辐射降温使水汽凝结而成。

Using the data of heavy fog at 6 stations in Anshun from 1961 to 2010, Micaps data and NCEP（ 1 °× 1° ） reanalysis data, it is found that there were three circulation patterns, which were stationary front - fog （ Divided into the west （southwest） pattern and the middle pattern） and radiation fog, for the regional heavy fog in Anshun built based on the formation mechanism by the methods of synoptic meteorology. And the corresponding models were established. Selecting typical examples and analyzing the dynamic and thermodynamic features of the different heavy fog weather, the results show that ： the formation of the west （southwest） stationary front - fog mainly due to water vapor in the low layer rises and the downdraft in the middle layer makes aqueous vapor condense only in surface layer with low ambient temperature when stationary front is in steady state. When stationary front with the strong warm and moist air adveetion at the front moves to the central Guizhou and there is the shear line in southern Guizhou, the middle stationary front -fog will appear. So the middle stationary front -fog also has the feature of advection fog. With the downdraft in whole layer, aqueous vapor was converged at surface layer by subsidence inversion and condenses because of radiation cooling in the night into visible moisture, which is radiation fog. So radiation fog has a very thin saturated layer.