Reconstruction of initial continuous current waveform in rocket-triggered lightning from close magnetic measurement

Abstract:

We present a new method that remotely measures the initial continuous current in rocket-and-wire triggered lightning using a compact dB/dt sensor deployed at 78 m distance from the channel base. The current waveform retrieved from the numerical integration of close magnetic signals perfectly shows the general feature and all the slow variations (such as M-components) embedded in the channel-base current measured with a shunt. In comparison with the shunt measurement, the new method has the advantage of significantly reduced noise (with the lower detection threshold as small as a few mA). Our method could be applied to remotely probe the initial continuous current in upward lightning from high objects and altitude-triggered lightning, as well as continuing current in natural cloud-to-ground lightning strokes at a sufficiently close range.