长江山区航道剖面能见度分析及局地影响因素初探

为了分析三峡航道不同区域能见度基本特征，比较不同垂直剖面、沿江距离对局地能见度的影响，基于中国气象局沿江、剖面布设的12个能见度监测点近3 a观测资料，对比分析了三峡航道涪陵、万州、宜昌3组区域12个监测点的能见度时空分布特征，并对能见度的局地差异做了初步讨论。结果表明：涪陵区雾情对航运安全影响最大，万州和宜昌区其次。涪陵区和万州区雾日的月际变化趋势一致，5、6月和11、12月为大雾高发时期。不同剖面能见度的日变化分析表明早晨至上午时间为大雾高发时段，午后至傍晚前为大雾低发时段。通过能见度与局地因子的关系模型验证，三峡航道能见度局地差异大部分源于监测点的海拔高度及可能的水体影响等，同组区域内，高海拔点、临近水域点平均能见度明显偏低，雾情频次也相对较高

ANALYSIS OF VERTICAL VISIBILITY ALONG THE YANGTZE RIVER WATERWAY AND THE POSSIBLE LOCAL FACTORS

The world famous“Three Gorges Reservoir”is situated on the middle reaches of the Yangtze River. The fina1 water leve1 reaches 175 meter and the reservoir covers 10000 km of region. It has more foggy days on the river because of the water bodies and special terrain, seriously affecting waterway. And the foggy days is becoming more and more dangerous in the Yangtze River waterway. With the support of the government of Three Gorges Project construction and China Meteorological Administration, 15 meteorological stations and 12 visibility instruments have been installed in 2009, in order to analyze the influence on the regional climate environment. In this paper, based on the meteorological data of 12 meteorological stations along the Yangtze River in the Three Gorges Reservoir Area, visibility of the Yangtze River waterway have been analyzed, in order to analyze the characteristics of visibility along the different regions of Three Gorges waterway, compare the influence of the different vertical sections and the distance from the river.The spatial temporal distribution characteristics of visibility of Fuling, Wanzhou, and Yichang region have been discussed．It is found that the frequency distribution of visibility of Fuling has the greatest impact on the shipping safety, followed by Wanzhou and Yichang. The monthly variation trend of foggy days in Fuling and Wanzhou district is consistent. The variation within the year is 6 month period. The frequency of fog was more higher in May, June, November and December of the year. The monthly variation of fog is larger in Yichang district. The fog occurs at night and in the morning time, and the frequency peak generally appears in the morning. By verifying the relationship model of visibility and local factors, it showed that the visibility differences of the Three Gorges waterway were due largely to the altitude and water and topography of the monitoring points. The visibility is lower and foggy frequency is relatively higher if the altitude of monitoring points is higher or near the water, and vice versa.