两次高压电线积冰过程气象成因分析

Analysis of the causes for two high-voltage wire icing cases

对2008年2月25—26日和2009年1月5—9日湖北省500 kV高压输电线路张恩1回线307号杆塔采集到的两次积冰过程进行分析,结果表明:两次积冰过程具有相似的环流形势即500 hPa中高纬为两槽一脊。低纬度地区有短波槽活动,700 hPa低空急流明显,地面处于冷锋前。低空急流、地面冷锋均有利于冰冻雨雪天气发生,且积冰过程中均有良好的温湿条件,并都伴有降水发生,这些条件都为积冰形成提供了良好的动力及热力条件。而2008年积冰过程大气温度垂直结构存在暖层,是造成两次过程形成机制不同的原因之一。

Two icing cases happened on 500-kV high voltage transmission lines in Hubei Province during February 25-26, 2008 and January 5-9, 2009. Study showed that the circulation patterns in both cases are similar： there were two troughs and a ridge in high latitudes, a short-wave trough in low lati- tudes at 500 hPa, a low-level jet at 700 hPa, and a surface cold front. The low-level jet and surface cold front were conducive to the occurrence of freezing rain and snows. Also, icing processes involved precipi- tation, certain temperature and humidity conditions. These conditions provided good potential and thermal conditions for the formation of icing. A warm layer existed in the vertical temperature structure of the at- mosphere in the 2008 case, but not in the 2009 case. This resulted in the difference in formation mecha- nisms of the two cases.