海南文昌地区夏季雷暴地面电场观测及分析

OBSERVATION AND ANALYSIS OF GROUND ELECTRIC FIELD OF SUMMER THUNDERSTORM IN WENCHANG AREA OF HAINAN

为了了解海南文昌地区雷暴电环境的基本特征,利用安装于距地面3.5 m楼顶的大气电场仪和雨量资料,分析了文昌夏季阵性降水对应不同类型的电场特征、单体雷暴活动电场演变规律及降水和闪电之间的关系。通过分析发现过观测场顶部无闪电的阵性降水过程地面电场极值较小,电场和降水基本呈现反向同步的变化特征。过顶单体雷暴在闪电发生前,地面电场提前产生扰动,明显的扰动一般提前于电场过零点约15～30分钟,第1次闪电发生一般提前于降水20～30分钟。统计多次较强单体雷暴过程发现,阵性降水之前和降水过程中闪电比较密集,降水后期闪电较少发生,降水强度和闪电频次有一定的正比例关系。典型单体雷暴进入衰退期电场变化呈现出较为明显的阻尼振荡(EOSO)。

In order to understand the basic characteristics of thunderstorm electrical environment in Wenchang,this paper employs the atmospheric electric field and rainfall data to analyze the showery precipitation in summer in Wenchang corresponding to different types of electric field characteristics,as well as the relations between precipitation and flash frequency.The analysis shows that lightning-free showery precipitation corresponds to small extremes of the electric field;the electric field generally varies in anti-synchronization with precipitation.Prior to the occurrence of lightning,overhead single-cell thunderstorms experience disturbance in the electric field and usually significantly about 15 to 30 minutes before the electric field passes the zero point;their first lightning generally occurs about 20 to 30 minutes earlier than the precipitation does.Statistics of a number of strong showery precipitation from single-cell thunderstorms shows that before and during the showery precipitation,lightning is more intensive than in the late period and there is some proportional relationship between rainfall intensity and lightning frequency.When a typical single-cell thunderstorm gets into recession,its electric field changes in remarkable damped oscillation（EOSO,end of storm oscillation）.