Infrasound for Detection, Localization, and Geometrical Reconstruction of Lightning Flashes

In the context of the infrasound network of the International Monitoring System of CTBT, infrasounds and low- frequency sounds are reviewed as a method to characterize lightning flashes in a complementary way to electromagnetic observations. The physics of lightning discharges is briefly recalled, in relation with thunder characteristics and mechanisms of generation. The possibilities and limitations of following storms at various distances by means of remote acoustic detection of lightning flashes is discussed. Influence of distance, wind and ambient noise is examined. The three-dimensional reconstruction of lightning flashes is illustrated by several examples from a recent 2012 observation campaign in the French Mediterranean region. Comparison with outputs from a high-resolution electromagnetic lightning mapping array delineates the performances of acoustical reconstruction of individual lightning flashes for both intra-cloud or cloud-to-ground discharges. Analysis of a significant number of discharges allows to perform a statistical comparison of the two approaches. Special attention is brought to the lower parts of cloud-to-ground discharges. Opportunities for further investigations are finally outlined.