2008年低温冰冻雨雪灾害天气过程中贵州电线积冰气象条件分析

Discussion on Genesis of Wire Icing in Guizhou During the Freezing Rain and Snow Storm in January 2008

利用气象电线积冰观测资料、探空观测数据、自动站资料以及NCEP再分析资料,分析2008年低温冰冻雨雪灾害天气过程中贵州电线积冰的分布特点,讨论了贵州电线积冰的气象条件,并对电线积冰的融冰条件进行了讨论。分析认为此次低温冰冻雨雪灾害天气过程中,贵州电线积冰严重,积冰范围广、时间长,相对而言贵州中东部地区积冰较厚;贵州电线积冰主要是雨凇、雾凇或者雨凇、雾凇形成的混合积冰;静止锋降水和锋面逆温在雨凇的形成过程中起着重要的作用;气温较长时间维持在0～-5℃及低层水汽充沛决定了电线的积冰及其增长,积冰融化时,相对湿度在85%以下,积冰停止发展,且融冰快慢与局地升温程度有关。

Using the meteorological wire icing observations,radio sonde and surface observations,and NCEP reanalysis data,the distribution and intensity of wire icing in Guizhou Province during the hazardous sleet in 2008 are analyzed.The meteorological conditions for wire ice accretion and its melting in Guizhou are discussed.The results show that the serious wire ice accretion in Guizhou in the sleet is characterized by wide range,long lasting time and thicker wire ice in the east than the west.Wire icing events in Guizhou are mainly in forms of glaze,rime and mixed freezing consisting of glaze and rime.Quasi-stationary frontal precipitation and frontal temperature inversion play an important role in the formation of glaze ice.The condition that temperature maintains within—5—0℃for a relatively long period and sufficient water vapor exists in the lower level determines the wire ice accretion and its growth.Wire ice stops growing when relative humidity is below 85%,and the melting rate of wire ice is relevant to the local temperature rising rate.