浙江省沿海陆域与舟山海域地闪回击特征分析

Analysis of Return-Stroke Characteristics of Cloud-to-Ground Flashes in Coastal Land of Zhejiang Province and Zhoushan Sea Area

采用2016—2020年浙江省闪电定位资料,利用Access和MATLAB对浙江省陆域、舟山海域地闪回击特征进行分析。结果显示:浙江省陆域年平均地闪回击密度为1.97次·km^(-2)·a^(-1),正地闪回击密度为0.10次·km^(-2)·a^(-1),正地闪回击占总地闪回击的5.1%,正地闪回击平均电流强度为42.49 kA,负地闪为33.61 kA,正负电流强度比值为1.26。舟山海域年平均地闪回击密度为0.54次·km^(-2)·a^(-1),正地闪回击密度为0.06次·km^(-2)·a^(-1),正地闪回击占总地闪回击的11.1%,正地闪回击平均电流强度为49.81 kA,负地闪为47.77 kA,正负电流强度比值为1.04。浙江省陆域、舟山海域的北部区域的正地闪和负地闪回击电流强度均明显强于南部区域;舟山海域的正地闪和负地闪回击平均电流强度均分别比浙江省陆域的强,舟山海域的正负地闪回击平均电流强度比值明显小于浙江省陆域。不同区域正地闪与负地闪回击平均电流强度的比值有较大差异,舟山海域正地闪回击的比例特别高,正地闪回击的平均电流强度稍大于负地闪,通过大气电学和气象学分析,初步阐释其成因。

Based on the lightning location detection data of Zhejiang Province from 2016 to 2020,the return-stroke characteristics of cloud-to-ground flashes in the land of Zhejiang Province and Zhoushan sea area are statistically analysed by using Access and MATLAB.The results are as follows:the annual average density of cloud-to-ground flash return strokes in Zhejiang Province is 1.97 fl·km^(-1)·a^(-1);the density of positive cloud-to-ground flash return strokes is 0.10 fl·km^(-1)·a^(-1);the positive cloud-to-ground flash return strokes accounted for 5.1%of the total cloud-to-ground flash return strokes;the average current intensity of positive cloud-to-ground flash return strokes is 42.49 kA;the average current intensity of negative cloud-to-ground flashes return strokes is 33.61 kA;the positive and negative current intensity ratio is 1.26;the annual average density of cloud-to-ground flash return strokes in the Zhoushan sea area is 0.54 fl·km^(-1)·a^(-1);the density of positive cloud-to-ground flashes return strokes is 0.06 fl·km^(-1)·a^(-1);the positive cloud-to-ground flash return strokes accounted for 11.1%of the total cloud-to-ground flash return strokes;the average current intensity of positive cloud-to-ground flash return strokes is 49.81 kA;the negative cloud-to-ground flash return strokes is 47.77 kA;and the positive and negative current intensity ratio is 1.04.The positive and negative return stroke currents in the northern region of Zhejiang Province and Zhoushan sea area are significantly stronger than those in the southern region.The average positive and negative return stroke current intensities in the Zhoushan sea area are stronger than those in the land of Zhejiang Province.The ratio of positive and negative return stroke current intensities in the Zhoushan sea area is significantly smaller than that in the land of Zhejiang Province.The ratio of average current intensities between positive and negative cloud-to-ground flash return strokes is quite different in different regions.The proportion of positive cloud-to-ground flash return strokes is particularly high in the Zhoushan sea area.The average current intensity of positive cloud-to-ground flash return strokes is slightly higher than negative,the causes of which are preliminarily explained by analysing atmospheric electricity and meteorology.