Using lightning location system stroke reports to evaluate the probability that an area of interest was struck by lightning

Modern lightning location systems (LLSs) have become a useful tool in confirming or negating lightning as a cause of damage in forensic investigations. There are uncertainties in the reported locations of detected lightning that arise from electromagnetic propagation errors and need to be considered when used in forensic investigations. Methods to evaluate regions of confidence for individual stoke reports or to calculate probabilities of individual strokes having attached in a region are available but no consistent method for evaluating the probability that an area or asset of interest was struck/damaged by lightning. This paper discusses a methodology for calculating a probability that considers all detected lightning events relevant to such an investigation, and not just individual strokes. The method is based on previous work done by Huddleston et al. and adds to it using conditional probability theory. A case study, a photovoltaic plant where a solar panel was found damaged subsequent to a storm, is used to demonstrate the concepts of the methodology. It is possible to show that there is a 71% chance that the panel group from which the damaged panel came, was struck by lightning using LDN data alone. This can be compared with the rest of the solar panel plant (where it was noted that other solar panels had been replaced after the same storm) which had a 97% chance of having been struck by lightning. It is also shown how grouping strokes into flashes and using the methodology to calculate which area was struck by each flash, indicates the true strike area of interest better than only using individual strokes.