Reproduction of lightning electromagnetic field waveforms by engineering model of return stroke

In this short paper, a new "engineering" model of subsequent return stroke has been proposed. In the model, the propagation characteristic of a channel current follows the Diendorfer and Uman (DU) model in the bottom region but a current pulse attenuates further in the upper region. This model has succeeded in reproducing all the features of reported typical electric- and magnetic-field waveforms associated with natural subsequent lightning and triggered lightning.