Stratospheric Joule heating by lightning continuing current inferred from radio remote sensing



[1] The mean lightning current waveform of particularly intense lightning discharges is inferred from 52,510 radio wave recordings in the frequency range 1–200 Hz. The current waveform decays initially with a time constant of ∼2 ms, and the current lowers ∼60 C from cloud to ground within the first ∼10 ms of the discharge. The subsequent continuing current exhibits a decay time constant of ∼40 ms and lowers ∼170 C from cloud to ground within the next ∼100 ms of the discharge. The total charge transfer ∼230 C from cloud to ground deposits electrical energy into the stratosphere resulting from quasi-static (Joule) heating. The energy deposition is dominated by the lightning continuing current, and it is ∼10−5 J/m3 at 30 km height. It is speculated that the initiation of blue jets and gigantic jets in the stratosphere may result from lightning continuing current ≳100 ms which can be observed with radio waves at frequencies ≲10 Hz.