中文摘要：

利用北京闪电综合探测网（Beijing Lightning NETwork）在2011年8月9日的一次中尺度对流系统过境期间获得的7个站同步闪电地面电场变化资料,在采用蒙特卡罗数据处理方法对资料进行误差订正的基础上,基于非线性最小二乘拟合算法,深入分析了51次负地闪的127次回击中和电荷源的特征。多回击负地闪回击中和电荷源的水平分布尺度Le和垂直分布尺度ΔHe分别为13.0±9.3 km和2.1±1.7 km;两者之比Le/ΔHe为61.2±278.5。随着垂直分布尺度ΔHe的增大,水平分布尺度Le以及水平和垂直分布尺度之比Le/ΔHe呈减小趋势。对雷暴不同阶段负地闪回击中和电荷源的分析发现,雷暴自发展到成熟,再到消散阶段,回击中和电荷源最大高度呈先缓慢上升、后显著减小的变化趋势;这期间,电荷源的最低高度始终在距地面5 km左右,电荷源水平分布总体上自西北向东南方向移动,与雷暴云移动方向一致。与雷达回波的叠加发现,负地闪回击中和的电荷源主要分布在回波强度〉25 d BZ的区域,其中高度值≥7 km的电荷源占34%,主要分布在雷暴云对流活动较强的区域内部;高度值〈7 km的电荷源占66%,在雷暴云对流活动较强的区域内部和外围都有分布。

英文摘要：

Using the measurements from slow and fast antenna of 7 stations synchronized by GPS during a thunderstorm which passed over Beijing Lightning NETwork（BLNET）on 9 August 2011,the magnitude and location of charge neutralized by 127 return strokes of 51 negative cloud-to-ground（CG）lightning flashes are fitted by using nonlinear least-squares fitting algorithm after Monte Carlo data processing and correction in advance.The fitting results were analyzed from several aspects shown as below.（1）For the charge sources neutralized by the strokes in one multi-stroke negative CG lightning,the horizontal distribution range Le and the vertical distribution range ΔHe was 13.0±9.3 km and 2.1±1.7 km respectively,and the ratio Le/ΔHe was 61.2±278.5.As the vertical range ΔHe increased,the horizontal range Le and the ratio Le/ΔHe decreased.（2）When the thunderstorm evolved from developing stage into mature stage,the maximum height of the stroke charge sources raised up gradually.When the thunderstorm evolved into dissipating stage,the maximum height of the stroke charge sources significantly became less than before.Throughout this period,the minimum height of the stroke charge sources kept around 5 km and the horizontal locations moved from northwest to southeast while the thunderstorm moved in the same direction.（3）The superposition of the charge sources and the radar echo showed the charge sources of negative return-stroke were mainly concentrated inside the cloud region with radar reflectivity higher than 25 d BZ.The charge sources with height more than 7 km accounted for 34% of the total and were concentrated inside updrafts of convection,while the charge sources with height less than 7 km were about 66% and located both inside and outside updrafts of convection.