Publication Date:
2013-11-14
Description:
[1] In 2009 and 2010, a multi-station network of fast and slow antennas was installed on the edge of a relatively high-latitude forest region in Da Hinggan Ling (50.4°N, 124.1°E) of Northeastern China. The registered 185 positive cloud-to-ground (CG) flashes containing 196 return strokes were analyzed in the paper. It was found that 71.89% of the positive CG flashes contained continuing current. The average duration of continuing current was short with an arithmetic mean (AM) value of 33.29 ms and a geometric mean (GM) value of 16.74 ms; only one continuing current endured longer than 150 ms, probably because of the small size of storm cell in this relatively high-latitude region. The vast majority (94.59%) of positive CG flashes was characterized by a single stroke, and the average number of stroke per flash is 1.06. The average charge transferred by positive stroke and continuing current, based upon the analysis of 5 flashes with well documented simultaneous measurements of more than 5 station, was +5.2 C from a height of 6.0 km (above ground) and +10.2 C from a height of 6.4 km, respectively. The charge moment for + CG strokes ranged from +13.7 C km to +55.9 C km, while that for continuing current ranged from +29.0 C km to +96.9 C km, respectively. The preliminary breakdown process in positive CG flashes can be classified into three types, namely type-S (same), type-D (different) and type-C (chaotic) according to the disparities in the initial polarity of bipolar pulses from the return stroke, which account for 62.92%, 23.60% and 13.48%, respectively. According to the electric field waveforms indicative (or not indicative) of intra-cloud (IC) discharge, positive CG flashes are classified into four types, i.e., ordinary positive CG flash (63.78%), hybrid + CG-IC flash (21.08%), hybrid IC- + CG flash (5.41%), and hybrid IC- + CG-IC flash (9.73%). About 15.14% of the recorded positive CG flashes were byproduct of IC lightning discharge.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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