Characteristic parameters of positive cloud-to-ground lightning channel

The high time-resolved spectra of two natural positive cloud-to-ground (CG) lightning of which one of them contains multiple return strokes have been taken by a high-speed slit-less spectrograph. On combining with the synchronous electric field change waveform, the temperature, electrical conductivity of the return stroke channel, radius of the core current channel and the peak value of current are calculated. The correlation between the peak current and the time interval of five M components which overlapped with the continuous current following the subsequent return stroke R1 of multiple return strokes positive CG lightning were analysed. The results show that the average temperatures of the return stroke channels for two positive CG lightning are about 28,900–29,800 K, the radius of the core current channel is about 0.36–1.01 cm, the estimated peak currents of the return strokes are about 18.6–38.0 kA, which are all larger than the typical values of common negative CG lightning. The peak currents of the M components are positively correlated with the time intervals between them.