Propagation effects on lightning magnetic fields over hilly and mountainous terrain

In this paper, we analyze the propagation effects of hilly and mountainous terrain on lightning magnetic fields by using a three-dimensional (3-D) finite-difference time domain (FDTD) method. We show that the waveshape, peak value and time delay of the magnetic fields can be significantly affected when propagating along a hilly terrain. It is found in particular that the time delay of the magnetic field increases with increasing height of the mountains. The observed time delays resulting from the propagation along a hilly terrain might impact the accuracy of lightning location systems based on the time-of-arrival technique.