江苏省沿海高速公路雾的时空变化特征研究*

利用江苏省沿海高速公路2012年6月~2014年5月逐分钟AWMS实时监测数据,按能见度大小和物理成因对雾的发生过程进行分类统计,分析了它们的时空变化特征,探讨了造成各种时空分布差异的原因。研究结果表明:1江苏省沿海高速公路不同浓度雾的日、年变化特征相似,一天中各种浓度雾均出现在夜间的21时~次日凌晨07时之间,消失在凌晨05时~上午09时之间,持续时长由长到短依次为:重浓雾、浓雾、大雾和雾;一年中,夏季和秋季是各种浓度雾的重发和多发季节;2局地地理环境差异对不同地段雾日数的分布有着明显的影响,不同浓度雾的发生频次在空间分布上也有明显差异,能见度为1 000~500 m、500~200 m和200~50 m三种浓度雾的多发区均在公路北段;而能见度小于等于50 m的重浓雾频发区出现在高速公路中段;3不同物理成因导致的各类雾的发生频次和时间分布有明显的差异。团雾出现频次最多,辐射雾次之,蒸发雾最少;一天中,团雾出现的时间覆盖范围最宽,平流雾次之,锋面雾最窄;消失的时间跨度为团雾最大,平流雾次之,蒸发雾最窄;持续时间为混合雾最长,锋面雾次之,团雾最短;团雾的频发季节为夏季,辐射雾的多发季节为秋季,平流雾在冬季出现概率最高;4辐射雾多发于北部地区,平流雾多发于南部地区,团雾的空间分布比较复杂,与江苏沿海地区复杂的地形分布有关。

Study on temporal and spatial occurrence pattern of fog on the coastal expressway of Jiangsu province

Based on the observed data of the Automatic Weather Monitoring System on the Coastal Expressway of Jiangsu Province during June in 2012 to May in 2014, in this paper, the temporal and spatial occurrence pattern was analyzed according to the classification of the visibility values and main physical formation mechanisms in fog occurrence processes statistically and the causes brought about the difference of these temporal and spatial pattern was discussed. The results showed as follows: (1) The daily and annual variations pattern of the fog (visibility in the scope from 1000m to 500m), thick fog (visibility in the scope from 500m to 200m), heavy fog (visibility in the scope from 200m to 50m) and dense fog (visibility is less than 50m) was similar on the Coastal Expressway of Jiangsu Province. All of the fog events occurred during 9 pm in a day to 7 am of the next day and disappeared from 5 am to 9 am in a 24 hour cycle. The lasting duration from long to short is followed by dense fog, heavy fog, thick fog and fog. Summer and autumn in a year were the seasons of high occurrence frequency for all fogs of different concentrations (or visibilities) in a year. (2) There are some obvious differences of spatial distribution between the occurrence frequencies of different concentration fogs. The fogs of the visibilities in the sections from 1000 m to 500 m, from 500 m to 200 m and from 200 m to 50 m often appear in the north part of the expressway and the dense fogs of the visibility less than 50 m occur in the middle part of the expressway with high occurrence frequencies. The diversity of local geographic environment has a remarkable impact on the spatial distribution of fog days with different concentrations. (3) On the expressway, the fogs resulted from different physical causes had the different temporal variation patterns. In these two years, the dumpling fogs appeared in the highest frequency, the radiation fogs taked the second place and the evaporation fogs occurred in the minimum numbers. In a day, the dumpling fog had the widest range in the appearing and disappearing times, the advection fog ranked the second, the occurrence of the frontal fog was in the most narrow appearing time range and evaporation fog had a shortest disappearing scope. The mixed fog lasted the longest time, the frontal fog situated in the second and the dumpling fog had the shortest duration. The high occurrence frequency season of dumpling fog was summer, the multiple season of the radiation fog was autumn and the advection fog had a larger occurrence probability in winter. (4) The radiation fogs were prone to the north part of expressway, the advection fog often occurs in the south part but the spatial distribution of dumpling fog was quite complicated why it was closely related to the complex topography in the coastal areas of Jiangsu Province.