三峡库区航运气象条件分析

利用三峡库区9个沿江测站气象要素，分析了长江航道的(三峡库区段)江面风、水温、能见度资料。就能见度强度和低能见度的时空分布特征、变化情况和航道出现典型低能见度的天气形势进行了研究。结果表明：①该航段的风向风速和水温对航行安全没有明显的影响；②能见度成为影响三峡河道航运极其重要的因素；③三峡库区航道低能见度天气存在比较明显的时空分布差异：冬季较夏季易出现影响航道安全的低能见度天气，重庆到忠县段出现低能见度的机率较大，而万州至巫山段较少出现低能见度现象；④长江航道低能见度在年际间除重庆和忠县外总体有减小的趋势,季节分布中在冬季出现最多，其次是秋季、春季，夏季最少；低能见度现象持续时间大部分在2小时以下；⑤造成长江航道低能见度出现的原因除城市环境外，主要的天气原因是由于盆地受地面冷高压控制，为阴天或阴雨天气，形成雾或雨雾。

ANALYSIS ON SHIPPING METEOROLOGICAL CONDITIONS IN THE THREE GORGES RESERVIOR AREA

Based on meteorological data of 9 observation stations along the Yangtze River in the Three Gor- ges Reservoir Area, river surface wind, water temperature, and visibility of the Yangtze River waterway have been analyzed. The intensity of visibility and the spatial-temporal distribution characteristics of low visibility were analyzed statistically, and furthermore the correspondent weather conditions of low visibility were also studied. The results showed that (1) the direction and velocity of wind and the water temperature in this region cannot exert obvious influence on sailing safety; (2) visibility is a fundamental factor influen- cing sailing safety in this region; (3) the weather inducing low visibility exhibits obvious characteristics of spatial-temporal distribution: low visibility is more probable to appear in winter than in summer,and com- pared with the section from Wanzhou to Wushan,low visibility is more possible to emerge in the section from Chongqing to Zhongxian; (4) except for Chongqing City and Zhongxian County,there is a decreasing trend of annual low visibility phenomenon in the Yangtze River waterway generally, with the lasting time of low visibility phenomenon less than two hours each time,most probable to appear in winter,then in au- tumn and spring, and least probable in summer; (5) in addition to the city environment, the weather condi- tion contributes to the low visibility phenomenon in the waterway,and the main weather cause is that the basin is controlled by surface cold high-pressure, which induces cloudy or rainy weather. The fog or rain fog of cloudy or rainy day resulting in low visibility phenomenon.