We introduce new methods for the analysis of complex three-dimensional lightning data produced by
Lightning Mapping Arrays and illustrate them by cases of a mid-latitude severe weather producing
thunderstorm and a tropical thunderstorm in Colombia. The method is based on the characteristics of
bidrectional leader development as observed in LMA data (van der Velde and Montanyà, 2013), where
mapped positive leaders were found to propagate at characteristic speeds around 2 · 10^4 m s-1, while
negative leaders typically propagate at speeds around 10^5 m s-1. We fit slopes (t-x, t-y, t-z) to approximate
leader speed, which can be used to determine the polarity, and summarize flash rate and polarity
characteristics in a 3D grid over time. The summarized data can be used to follow charge structure
evolution over time, as well as climatological studies comparing lightning parameters with the
meteorological environment of storms.Postprint (author's final draft
