The peak, rise time and the half-width of lightning generated electric field derivatives over finitely conducting ground

Electromagnetic fields generated by lightning change their character as they propagate over the ground surface due to the selective attenuation of high frequency signals by the finitely conducting ground. Thus, the peak and the peak derivatives of the electromagnetic radiation fields measured at a distance from a lightning flash may deviate from their true value depending on the distance of propagation and the conductivity of ground. If the measured fields are used to estimate the peak current derivative, without any correction for propagation effects, one may obtain peak current derivatives which could be several times smaller than the actual one in the lightning channel.