云南省两套闪电定位系统地闪回击参数对比及探测性能分析

Comparison of Cloud-to-Ground Lightning Parameters and Detection Performance ofTwo Lightning Location Systems in Yunnan Province

根据2017—2020年云南省ADTD二维和VLF/LF三维闪电定位系统观测资料,对比两套系统地闪回击参数分布差异。在实际回击位置和雷电流强度信息难以获得的情况下,研究利用两套系统反演资料对相同回击事件的识别匹配和时空阈值选取方法,分析相对定位偏差。结果表明:两套系统的回击密度、雷电流幅值在滇东、滇西南和滇西北等地的空间分布差异明显,由三维系统得到的回击密度较大,但二维系统雷电流幅值均值更高。两套系统均以单回击地闪占比更高,正地闪中的单回击地闪比重较负地闪更大,三维系统对于0~5 kA负回击小幅值电流的探测效率有所提高。通过采用10km、1 ms的时空阈值匹配窗口,得到两套系统对于同一次回击的相对定位时间差主要集中在0.05 ms内,距离偏差集中在1 km内。系统匹配回击在滇中、滇西南的时空偏差较小,滇西北的偏差较大。从回击极性、相关系数、相对误差、幅值比及幅值累积概率等方面,分析得到两套系统对于相同回击事件的电流强度反演结果一致性较好,验证了应用系统反演资料对于同一回击事件的识别匹配方法是客观可靠的。

Based on observational data from the ADTD 2D and VLF/LF 3D lightning location systems in Yunnan Province from 2017 to 2020,this study compared the differences in the distribution of cloud-toground(CG)lightning parameters between the two systems.In situations where obtaining information on the actual location and current intensity of lightning is challenging,this study researched the identification and matching method and spatiotemporal threshold selection method for the same CG lightning stroke event by using inversion data from both systems.The detection efficiency of both systems was also analyzed.The results show significant differences in the spatial distribution of CG lightning stroke density and lightning current amplitude between the two systems in eastern,southwestern,and northwestern Yunnan.While the 3D system showed a higher lightning stroke density,the 2D system recorded a higher average lightning current amplitude.Both systems’positioning data revealed a higher proportion of singlestroke CG lightning,with a higher proportion of positive CG lightning compared with negative CG lightning.The detection efficiency of the 3D system for small amplitude currents(0-5 kA)with negative lightning strokes has been improved.By using a spatiotemporal threshold matching window of 1 ms and 10 km,we found that the positioning distance deviation of the two systems for the same stroke event was mainly concentrated within 1 km,and the time difference was within 0.05 ms.The temporal and spatial deviation of matched return strokes was relatively small in central and southwestern Yunnan but larger in northwestern Yunnan.Considering parameters such as lightning stroke polarity,correlation coefficient,relative error,amplitude ratio,and cumulative probability of amplitude,we found that the two systems had good consistency in the inversion results of current intensity for the same return stroke,indicating that the identification and matching method for the same lightning stroke event was objective and reliable.