导线覆冰自动观测实验与覆冰过程分析

Automatic observation experiment of icing on wires and analysis of icing processes

在贵州重冰区3个气象站和海拔2 500 m的梅花山野外观测点开展了3 a冬季的导线覆冰自动观测实验,利用观测实验获取的大量连续覆冰过程数据,对导线覆冰重量及其气象条件逐小时演变特征进行了深入分析.结果表明:一次完整的连续导线覆冰过程包括覆冰开始、增长、维持、减弱、消融到结束五个不同的阶段,持续时间较长的覆冰过程中间可能出现间断,而覆冰增长、维持、减弱几个阶段可能重复交替出现.覆冰过程开始一般以气温下降到0℃以下且相对湿度90%以上为标志,当出现浓雾或降水时覆冰出现增长,当既无降水也无雾时覆冰进入维持阶段;整个覆冰过程中温度均低于0℃且维持很高的湿度,中途若温度上升且无雾和降水则覆冰有明显减弱,当气温稳定上升到0℃以上同时湿度下降时覆冰过程结束.覆冰过程的开始和增长一般持续时间较长,而覆冰的消融和结束则十分迅速.在气象站观测到的覆冰以雨雾混合冻结为主,降水对覆冰过程的开始和增长有重要作用,而在梅花山野外观测到的多为雾凇覆冰,降水对覆冰的作用不如地势较低地区显著.

Based on the automatic observation experiment data of icing on wires in Guizhou Province（from 2011 to 2013）,a number of continuous process of icing and meteorological condition were thoroughly analyzed.The results showed that a complete process of icing includes five distinct phases,namely beginning,increasing,stable,decreasing and ablation or ending.In a long icing process,the phases of icing increasing,stable and decreasing usually appear alternately and repeatedly.Icing starts when temperature falls below 0 ℃ and relative humidity rises above 90%,and temperature keeps below 0 ℃ and humidity preserves high within the entire icing process.Ice-coat grows with temperature declining and rainfall or fog emerging,and turns to stable when temperature goes steady,rain ends and fog dissipates.Ice-coat decreases when temperature rises without any precipitation,and ablates when temperature rises above 0 ℃.The beginning and growing of icing are slow processes,while the melting and ending are relatively fast.The icing observed at meteorological stations is mainly caused by glaze and rime,with rainfall playing a key role.Whereas,those observed at field of high elevation are more caused by rime only,and effect of freezing rain is not as significant as those in low locations.