摘要
从四川省二郎山观冰站2002-2008年逐年1月份资料中选取12次覆冰过程和8次无覆冰过程,同时考虑2008年和2005年两个典型覆冰年共有覆冰日期(1月11~19日),利用NCEP/NCAR再分析格点资料,分析了大气环流特征。结果表明,西南地区有覆冰时,500hPa高度场距平合成图上呈"北高南低"的形势,贝加尔湖和巴尔喀什湖之间有一最大的温度负值中心,冷空气强盛且能延伸到西南地区;水汽源主要来自阿拉伯海、孟加拉湾的西南暖湿气流和南海的东南暖湿气流。通过分析二郎山地区2008年1月24~29日的风、温、湿廓线可知,750~650hPa均有逆温层,气温的日较差小,逆温层底部的相对湿度达到80%以上。750hPa有风向突变,低层为东北风,表明地面有冷空气回流;750hPa以上为西南风,即有较深高原槽或高原切变线活动。进一步分析还发现,在甘肃南部—四川中部—云南北部有一露点温度梯度极大值带,此极大值带内有风向的辐合,冷暖空气在此强烈交汇,配合大气环流和大气层结条件,可很好地解释西南地区产生电线覆冰的原因,对于提高此类覆冰过程的预报有重要的意义。
The 12 icing processes and 8 no-icing processes were selected from the freezing data at Erlang station in Sichuan in January from 2002 to 2008,and the same icing date(11~19 January) in 2008 and 2005 were taken.Using NCEP/NCAR reanalysis grid data,the circulation features of the icing and no-icing processes were analyzed.The results show that,in icing process in Southwestern China,500 hPa height anomaly field is 'north-higher and south-lower';There is a maximum negative center of strong cold air around Baykal Lake and the cold air can extend to the Southwest China;the vapor source is mainly the southwest air from Arabian Sea,Bay of Bengal and southeast air from South China Sea.The wind,temperature and humidity profiles in Erlang area on 24-29 January 2008 have obvious features.They are inversions between 750 hPa and 650 hPa,small diurnal range temperature,relative humidity over 80%,wind direct change on 750 hPa,cold air at the low level and warm air above 750 hPa,that is,deeper trough or plateau shear line activities above 750 hPa.Further studies indicate that there is a maximum zone of dew-point temperature gradient along southern Gansu-Central Sichuan-Yunnan,because winds converge around it,cold and warm air also confluence here.With the conditions of circulation and atmospheric stratification,the electric wire freeze in Southwestern China can been well known and the prediction of such weather events can been improved.
出处
《高原气象》
CSCD
北大核心
2011年第3期641-650,共10页
Plateau Meteorology
基金
西南电力设计院委托科研项目"输电线路覆冰数学模型研究"
国家重点基础研究发展计划项目(973计划)(2007CB411506)共同资助
关键词
西南地区
电线覆冰
大气环流
垂直廓线
水汽输送通道
Southwestern China
Electric wire freezing
Atmospheric circulation
Atmospheric stratification
Vapor transmission routeway