低纬高原大气电场特征及其在预警中的应用

通过对2006年7月- 2007年6月云南地闪定位网探测资料和玉溪大气电场仪资料分析,研究了高原晴天大气电场和雷暴天气过程的电场演变特征.结果表明:高原晴天大气电场具有明显的日变化和月变化特征.低纬高原地区雷暴云具有偶极性和三极性两种结构,但大多数雷暴具有偶极性电荷结构,不同电荷结构的雷暴云的放电特征不同,偶极性时主要为负地闪,地闪活动较活跃；三极性时主要是正地闪,地闪活动较少.根据雷暴云近地面电场变化特征,探讨了大气电场仪预警地闪的方法,首次提出极性变化预警法,其命中率和提前预警时间都明显优于阈值预警法.

Electrical Characteristics of Atmosphere in the Lower Latitude Plateau and Its Application in Lightning Warning

The characteristics of atmospheric electric field in fair weather and thunderstorm in Yuxi region are analyzed by using the data obtained from Yunnan Lightning Location System and atmospheric electric field mill from July 2006 to June 2007.The results show that there exist diurnal and monthly atmospheric electric field variations in fair weather in the lower latitude plateau.The charge structures of thunderstorm are both dipole and tripole,but most thunderstorms have a dipole charge structure.Thunderstorms of different charge structures are of different characteristics of discharge.The negative polarity of electric field underneath thunderstorm is main negative discharge and the activity of the cloud-to-ground(CG) flash is very active.The positive polarity of electric field underneath thunderstorm is main positive discharge and the activity of the cloud-to-ground flash is very weak.The methods of the CG lightning warning by the electric field mill are studied based on the variation characteristic of thunderstorm electric field.The polarity change early warning method is proposed for the first time.Its POD and LT are better than that of the threshold warning method.