We report preliminary results of cloud-to-ground lightning observations in the South region of Brazil (specifically the Rio Grande do Sul State) in the summer of 2005/06. A total of 33 cloud-to-ground flashes from three thunderstorms were recorded with a Redlake MotionScope 8000S digital high-speed camera (1,000 frames/s) synchronized with GPS. The Brazilian Lightning Location System (BrazilDat) was already covering this Brazilian State at the time of the observations. We could find some preliminary statistics about the cloud-to-ground lightning parameters: stroke multiplicity, continuing current duration, total flash duration, interstroke interval and number of strike points. An interesting parameter found was the high percentage of positive flashes. Based on reprocessed network solutions, we found that 61% of the observed flashes were positive, while a 19-month average was ~34%. This is the first time an accurate-stroke-count methodology is applied over the south of Brazil, where the thunderstorms were already found to be particular by some authors in terms of very high flash rate, very high flash density and frequent occurrence of Mesoscale Convective Systems.
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