Numerical evaluation of electric field changes radiated by cloud-to-ground lightning stepped leader

Abstract In order to investigate the characteristics of electric field changes radiated by lightning stepped leader, a dipole method with attenuation function is proposed.Electric field changes associated with the lightning stepped leader channel at various observation points with different ground conductivity are explored.The results show that when the observation point is near the bottom of the stepped leader channel, the electric field amplitude decrease with the increase of the height of the stepped leader tip.However, as the distance increase, the height of the stepped leader tip has less effect on the electric field changes.For the stepped leader channel at given distance, the amplitude becomes larger first and then smaller.The rise time the peak of the electric field changes significantly in propagating over finitely conducting ground.Due to the decrease of ground surface conductivity, the simulated rise time of the electric field changes increase obviously and the amplitude of the electric field attenuate faster.