公路能见度的优劣与气象条件密切相关,影响公路能见度的天气现象主要有雨、雪、雾、霾、沙尘等。本研究利用全国间隔为5km的气象站2002年9月至2010年3月逐日地面气象观测资料,以及全国2413个自动气象站2008年1月1日至12月31日逐小时能见度及地面气象观测资料,分析了天气现象对公路能见度的影响。根据高速公路上行驶车辆对能见度的要求,结合中国大陆地区的实际情况,确定低能见度范围是水平能见度距离小于1000m,考虑到不同距离的低能见度对交通运输造成的影响程度不同,将低能见度划分为3个等级。利用统计学方法分析了影响高速公路的天气现象(雨、雪、雾、沙尘)的时空分布特征,以及全国1h降水与能见度的相关关系。研究结果表明,不同天气现象影响低能见度的时段不同;影响公路低能见度的主要天气现象中,就影响程度而言,雾对低能见度的影响最大;从影响范围上,各区域有所不同,新疆南疆盆地、内蒙古西部、青海北部等地区主要受沙尘影响,东北、华北、西南等地受雨雪影响较大,江南和华南等地主要受降雨影响。

Studying and mastering the meteorological factors influencing highway visibility and its correlation are the basis of highway visibility forecast. The weather phenomena influencing highway visibility mainly include rain, snow, fog, haze, dust etc. In this study, daily surface meteorological observation data from the meteorological stations at a distance of 5 kilometers a (from September in 2002 to March in 2010), and hourly visibility and surface meteorological observation data from the 2413 automatic meteorological stations (from January 1 to December 31 in 2008)are utilized. the characteristics of the temporal and spatial distribution of rain, snow, fog on the national highway and the relationship between the 1 hour rainfall and visibility are studied and analyzed be means of statistical methods. (1) Compared with other weather phenomena, the effects of fog on the visibility is the largest, and the low visibility range resulted from fog effect is mostly below 200 m, the frequency distribution of rain, snow and dust in time is uniform, and the influence of low visibility ranges in 500~1000m. (2) In each area of China, the main weather phenomenon that affects low visibility of highway are different. Basin in the south of Xinjiang and Inner Mongolia and other places are more influenced by dust; Northeast, North China, Tibet and other places are affected by rain and snow; South and southeast of Tibet are mostly influenced by rain. (3) The higher frequency regions with low visibility caused by precipitation are mainly the Yangtze River Basin, south of the Yangtze River, Southern China and other places. At the same time, there is negative correlation between rainfall intensity and visibility, but not to lump together. (4) The probability of low visibility in the snow weather is higher than that in rainfall weather. For snow weather, low visibility of 200~500m occours commonly, and in the rain, the probability of the low visibility of <200m appears higher than the low visibility of 200~500m.