Some features of negative cloud-to-ground flashes from a local thunderstorm based on accurate-strokecount study

Some properties of negative cloud-to-ground (CG) lightning flashes, in terms of number of strokes per flash, inter-stroke interval and the relative strength of subsequent stroke with respect to the first stroke in the flash, were presented by so called accurate-stroke-count studies based on a large data set including 1085 negative CG flashes occurring during a local thunderstorm. About 70% of negative CG flashes produced more than one stroke with the maximum number being 17 and the averaged number being 3.3. During the whole life cycle of this thunderstorm, the occurrence of single-stroke flashes varied significantly, leading to the variation of averaged number of strokes per flash. The inter-stroke interval showed a tendency to decrease with the increasing number of stroke per flash and the geometric mean for all inter-stroke intervals was 62 ms. In general, the strength of subsequent stroke with respect to the first stroke decreased with the stroke order, giving a geometric mean value of 0.52, while about 41.4% of multiple-stroke flashes contained at least one subsequent stroke stronger than the first stroke in the flash. There was a weak tendency for the higher multiplicity flash to have stronger first stroke.