2017 - EMP Commission - Recommended E3 Waveform for Critical Infrastructures
As described in this report, there is a need to have bounding information for the late-time (E3) high-altitude electromagnetic pulse (HEMP) threat waveform and a ground pattern to study the impact of these types of electromagnetic fields on long lines associated with the critical infrastructures. It is important that this waveform be readily available and useful for those working in the commercial sectors.
While the military has developed worst-case HEMP waveforms (E1, E2, and E3) for its purposes, these are not available for commercial use. Therefore, in this report openly available E3 HEMP measurements are evaluated from two high-altitude nuclear tests performed by the Soviet Union in 1962. Using these data waveforms and an understanding of the scaling relationships for the E3 HEMP heave phenomenon, bounding waveforms for commercial applications were developed.
Since the measured quantities during these tests were the magnetic fields, it is possible to compute the electric fields assuming ground conductivity profiles that produce significant levels. There are other profiles that would compute even higher electric fields, but some of these profiles do not cover a very large area of the Earth.