A CASE STUDY COMPARING THE LOSSY WAVE EQUATION TO THE CONTINUITY EQUATION IN MODELING LATE-TIME FIELDS ASSOCIATED WITH LIGHTNING

摘要

An investigation is presented into lightning-related transient electric field and conduction current densities due to the redistribution of charge by the return stroke (late-time effects). A qualitative comparison is made between the late- time vertical electrical field magnitudes predicted by two solutions via the continuity equation/Poisson's equation and the continuity equation in conjunction with the lossy wave equation. The differences between these results indicate that the magnetic energy density created by a lightning discharge generally provides relevant changes in the resulting electrical field waveforms as radial and vertical distances increase from the lightning discharge. That is, the accuracy of the conservative field assumption x E = 0 decreases with the distance from the point of excitation to the point of observation of the electric field for the study conducted. This observation suggests the use of the lossy full wave equation, when computationally feasible, for the prediction of late-time electric field behavior. This study addresses trends in the general behavior of the two solutions over region 0 <= r <= 30 km and 30 <= z <= 50 km. [Vol. 9, No. 2 (1994), Special Issue on The Numerical Computation of Low Frequency Electromagnetic Fields, pp 98-110]