土壤湿度对不规则起伏地表雷电垂直电场传播影响的研究

The Propagation Effect of Soil Moisture on Lightning Vertical Electric Field over Irregular Terrain

本文采用二维fractional Brown motion(f Bm)随机分形界面模拟不规则起伏地表,基于Longmire-Scott提出的土壤电参数等效模型(L-S模型),分析研究不规则起伏地表的土壤湿度对地闪回击垂直电场传播的影响。结果表明:(1)地表的不规则起伏程度主要会引起垂直电场峰值的衰减和上升沿时间的滞后。随着地表不规则起伏程度的增大,垂直电场峰值衰减越明显,且波形上升沿时间增长。(2)无论地表不规则程度如何,随着土壤湿度的增大,垂直电场的衰减反而减小。(3)总的来说,地表的不规则程度越大,土壤湿度越小,垂直电场的峰值衰减越大,波头上升沿时间越长。

A two-dimensional fractional Brown motion（f Bm） model was used to describe the irregular terrain, and the Longmire-Scott soil-parameter frequency dependent model was applied to investigate the propagation effect of soil moisture on the lightning vertical electric field over irregular terrai ns. Main results are as follows：（1） The surface irregularity can lead to the attenuation of the magnitude of the vertical electric field and lags of the rise time of the field waveform. With the increase in the surface irregularity, the attenuation of the vertical electric field intensifies and the rise time of the field waveform increases.（2） Regardless of the degree of surface irregularity, increases in the soil moisture will reduce the attenuation of the vertical electric field.（3） Generally, increases in the surface irregularity and decreases in the soil moisture can result in stronger attenuation of the vertical electric field and longer rise time of the field waveform.