2011—2015年安徽省高速公路低能见度变化特征

Distributional Characteristics of Low Visibility in Expressways over Anhui Province

利用2011—2015年安徽省高速公路自动气象观测站观测的能见度资料,分析了安徽省低能见度年、日变化及其与降水的关系,结果表明:受降雨影响,大别山区和皖南山区部分站点低能见度出现频率最高时段在汛期(5—9月),其他地区主要出现在10月和11月。低能见度出现时间存在明显日变化,夜间出现频率高于白天,19:00以后开始逐渐增多,日出前后达到最大,之后迅速减少。7—8月的13:00—17:00出现与降水相关的低能见度频率较高。不同季节里,各站低能见度出现最多的时间和频率存在一定差异,春季和秋季最低能见度主要出现在日出前后,冬季主要出现在夜间到日出之前,夏季江淮之间北部和淮北地区主要出现在日出前后,江淮之间南部到江南在一天各时间段内出现频率较为均匀。

Based on the meteorological observation data of visibilty, relative humidity, and precipitation from expressway automatic weather observation stations in Anhui from 2011 to 2015, the annual distrbution and diurnal variation characteristics in each seasons of low visibility in Anhui are analyzed. Results show that the low visibility events occur in October and November mostly except those happened between May and September in the mountain areas such as the Dabie Mountains and the southern mountainous areas of Anhui. The low visibilty events have remarkable diurnal variation with the frequency at night being much higher. The low visibilty events begin to increase at 19：00, reach a highest point before sunrise, then decrease rapidly. The low visibility events in summer in the afternoon are related to heavy rainfall. Seasonal differences exist in time and frequency of the low visibility： occurring mostly around sunrise in spring and autumn while at night before sunrise in winter; occurring before the sunrise in the nothern Anhuit, and no significant differences in the frequence during a day in the southern Anhui in summer.