Comparison of Cloud-to-Ground Lightning Parameters and Detection Performance of Two Lightning Location Systems in Yunnan Province
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-to-ground(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 single-stroke 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.
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