Measurement of Return Stroke Current With Magnetic Sensor in Triggered Lightning

Based on the magnetic field recorded with a magnetic sensor deployed at 130-m distance from the channel base, we remotely measured the return stroke current waveform in classical rocket-triggering lightning flashes, including 40 M-components and 48 return strokes (RSs) in eight triggered flashes observed during the summer of 2019. The current waveform retrieved from the close magnetic field is in excellent agreement with the coaxial shunt measurement. For return strokes, the amplitude error of the peak current is less than 1 kA. The error of the 30%-90% risetime is less than 0.1 mu s. The error of the half-peak width is less than 1 mu s. The error of charge transfer within 0.1 ms of the return strokes is less than 0.1 C. For M-components, the amplitude error of the peak current is about less than 0.3 kA. The error of the 30%-90% risetime is generally less than 4%. The error of the half-peak width is approximately less than 3%. The error of charge transfer within 0.1 ms of M-components is less than 0.02 C. The magnetic sensor is likely applicable to measure lightning current without direct current measurement at near range in rocket-triggered lightning or natural lightning flashes.