贵州冬季电线积冰及其天气成因分析

Analysis on Wires Icing and Its Weather Conditions in Guizhou Province

利用气象部门长期电线积冰观测和电力部门线路覆冰调查资料,对贵州冬季电线积冰的分布、类型特征与气象条件进行了综合分析,着重探讨了贵州电线积冰的形成机理和天气成因,主要结论:(1)贵州电线积冰的类型复杂多样,除具有雨凇、雾凇、雪凇(湿雪)三种基本类型外,还有雨雾混合凇、雨雪混合凇(雪凝)两种混合冻结类型;贵州电线积冰以危售最大的雨凇冰为主,混合冻结在贵州省分布十分普遍,这也是造成2008年贵州电网严重冰害的重要原因;(2)持续低温阴雨的凝冻大气是贵州电线积冰总的天气成因,其表现形式主要是冻雨但不局限于冻雨,此外还包括冻毛雨、雨夹雪、湿雪和过冷雾等多种天气现象,持续的凝冻天气过程往往有多种天气现象同时或交替出现,从而导致严重的覆冰灾害;(3)贵州电线积冰总体上属于较高环境温度下的低风速湿物理过程积冰,当地面气温持续降到0℃以下,出现降雨或浓雾是电线积冰开始与增长的关键气象条件,而最高温度上升到0℃以上是判断积冰转入消融的临界气象指标。

Using observation data of wires icing from meteorological stations and field investigation to power line ice-coating from local electricity sections, this study comprehensively analyzes the properties, classifications and distributions of wires icing in Guizhou Province as well as its weather conditions. Emphasis is placed on discussing the mechanisms of wires icing and its weather causes of formation. The results show that （1） there are multiple types of wires icing in Guizhou Region. In addition to glaze, rime, and wet snow, mixed freezing types of freezing rain and fog, freezing rain and wet snow are common. Glaze dominates and mixed freezing prevails in mountainous areas, leading to severe wires icing disasters. （2） The freezing weather of continual low temperature and rainy days are the weather conditions of the forma- tion of wires icing, which includes freezing rain, freezing drizzle, sleet, wet snow and freezing fog. （3） Wires icing in Guizhou is generally controlled by moist physical processes with temperature below or near0℃ and slow wind speed （〈6 m· s^-1）. In most cases wires icing starts and grows under weathers of freezing rains when the temperature falls below 0℃. Therefore, air temperature below 0℃ and occurrence of freezing rain, freezing drizzle, freezing fog or sleet are important indicators to judge wires icing.