广西输电线路覆冰典型年份的环流特征分析

采用NCEP/NCAR逐月再分析资料、广西北部43个气象台站的温度、湿度、风、降水、导线覆冰等观测资料以及广西输电线路覆冰资料,建立雨凇覆冰厚度计算模型,并得出气象台站的历史覆冰厚度序列。采用数理统计和合成分析等方法研究典型覆冰年份的时空特征、环流背景及气象要素变化特征,结果发现:广西输电线路覆冰主要出现在冬季的桂北,并有逐年减轻的趋势,MannKendall突变检验表明,存在1个明显的突变点,出现在1985年;广西典型覆冰年份,500 hPa欧亚大陆中高纬地区呈明显的"两槽一脊"型,广西高空处于南支槽前,地面受冷高压脊控制;赤道中东太平洋,从夏季到秋季,海温由偏高转为偏低,到冬季SSTA维持为负距平,说明广西输电线路覆冰与LA NINA事件有较密切的关系。当日最低气温在0.2℃以下,风速5 m·s-1,并伴有雨凇和弱降水,低温寡照天气时容易出现覆冰。

Analysis of the anomalous circulation characteristics of the typical years of conductor icing in Guangxi

The calculation model of ice thickness of glaze icing is established and the history data sequences of the ice thickness of the meteorological stations are calculated, based on the NCEP/NCAR monthly reanalysis data, and temperature, humidity, wind, precipitation, conductor ice coating observation data, and so on from 43 meteorological stations in northern Guangxi and transmission line ice coating data. The spatial and temporal distribution and circulation characteristics of typical ice coating years are studied by means of mathematical statistics and synthetic analysis. The results show that the ice coating of transmission line occurs mainly in winter and in Northern Guangxi. There is a decreasing trend year by year, the Mann Kendall significance test shows that there is a significant change in 1985. In the typical ice coating year of Guangxi, the height field at 500hPa in the mid-high latitudes of Eurasia showed "a trough and a ridge", Guangxi is located in front of the southern trough, and a cold high pressure ridge controls Guangxi surface. From summer to autumn, the sea surface temperature turns from high to low and the sea surface temperature anomaly SSTA in winter keep negative in the middle and East equatorial Pacific, therefore there is a close relationship between Guangxi ice and LA NINA events. HaveSbeenSproneSto ice coating when the minimum temperature is below 0.2 degree, the wind speed is less than 5m/s, and accompanied by glaze and weak precipitation, low temperature and less sunshine.