Quantitative Measurement Of Lightning Radiation Field And Research On The Characteristics Of Peak Current Intensity In Beijing Area

CG lightning is a strong discharge phenomenon between the cloud and the earth.It was often accompanied by high voltage,large current and strong electromagnetic radiation.Beijing Lightning Network(BLNet)was able to real-time observation and lightning orientation when the top thunderstorm weather process that happen in Beijing and surrounding regions.Compared with other lightning location systems,BLNet not only real-time monitor the CG lightning(Cloud-to-Ground lightning),but also real-time monitor the IC lightning(Intracloud lightning).The paper using the data of lightning fast electric field change collected by BLNet in Beijing regions during 2015-2017,on the basis of the accurate measurement of the electromagnetic field caused by lightning discharge,based on transmission line mode to estimating lightning peak current intensity of lightning discharge channels,on the basis of this,the paper studies the characteristics of the peak current intensity in Beijing regions and obtains the following conclusions:1)The CG lightning was about 25.1 percent of the total lightning,and the positive CG lightning was about 21.1 percent of the total CG lightning.20:00~23:00 was the highest frequency of lightning occurrence in Beijing regions,both the total lightning and the CG lightning,were the highest.2)There was 69.6 percent of positive CG lightning contains only first return stroke,the maximum return stroke number of the positive CG lightning was 11,the arithmetic mean of average return stroke number was 1.8,geometric mean was 1.5;There was 63.9 percent of negative CG lightning contains only first return stroke,the maximum return stroke number of the negetive CG lightning was 25,the geometric mean was 1.7 and arithmetic mean of average return stroke number was 2;3)The positive CG lightning return-stroke average peak current intensity arithmetic mean was 25.2kA,the geometric mean was 15.2kA;and the negative CG lightning return-stroke average peak current intensity arithmetic mean was 14.6kA,the geometric mean was 9.9kA;and the positive and negative CG lightning average peak current intensity arithmetic mean was 17.6kA,,the geometric mean was 13.2kA;the positive CG lightning first return-stroke average peak current intensity arithmetic mean was 27.0kA,the geometric mean was 17.7kA;the negative CG lightning first return-stroke average peak current intensity arithmetic mean was 15.1kA,the geometric mean was 12.2kA;and the positive CG lightning subsequent return-stroke average peak current intensity arithmetic mean was 22.2kA,the geometric mean was 11.8kA;the negative CG subsequent return-stroke average peak current intensity arithmetic mean was 13.2kA,the geometric mean was 9.6kA;the stronger CG lightning,that lightning return stroke peak current intensity in the range of >100kA,it was mainly distributed in the mountains of eastern,northeast,western and northern of Beijing and urban area.4)Analyzed the CG lightning peak current characteristics of the first return stroke and subsequent return stroke,found that the return stroke peak current of 37.5 percent multiple return stroke CG lightning at least one subsequent return peak current intensity is greater than the first return stroke,at the same time,it was also found the number of subsequent return stroke CG lightning peak current intensity is greater than first return stroke was about 24.7 percent of the total number of CG lightning return stroke.