Calculations of lightning return stroke electric and magnetic fields above ground

The first detailed calculations of lightning return stroke electric and magnetic fields above ground are presented. Waveforms are given for altitudes from 0 to 10 km and ranges from 20 m to 10 km. These waveforms are computed using the model of Lin et al. (1980) and a modification of that model in which the initial current peak decays with height above ground. Both the original and the modified models result in accurate prediction of measured ground-based fields. Return stroke field measurements above ground close to the stroke, with which the calculations could be compared, have not yet been made. Salient aspects of the calculated fields are discussed, including their use in calibrating airborne field measurements from simultaneous ground and airborne data.