Isolated Large Bipolar Pulse (ILBP) Produced by Lightning Discharge in Winter Thunderstorm

Abstract

We present the first analysis of a type of special lightning discharge event, called “isolated large bipolar pulse” (ILBP), produced in winter thunderstorm. ILBP produces single bipolar electric field change waveforms with pulse widths mainly in the range of 7 to 19μs. The initial positive half cycle and the negative cycle of the bipolar pulse are symmetrical with each other to some extent. ILBP is also a very energetic discharge process, producing very large electric field changes even larger than that produced by positive return strokes. Most of ILBPs are found to be isolated with other discharge processes on a time scale of 1 second, but a few ILBPs also seem to be the initiation of other discharge processes. Based on the similarities and differences between ILBP, narrow bipolar pulse (NBP) and negative return stroke (RS) in winter thunderstorm, we discuss the possibility of ILBP as a special version of NBP in winter thunderstorm and as a special type of negative RS.