Evolution of Lightning Occurrence and Characteristics during Thunderstorm Lifetime

Clustered lightning observations from the World-Wide Lightning Location Network (WWLLN), and Earth Networks Total Lightning Network (ENTLN) flashes assigned to the WWLLN clusters, are used to examine lightning occurrence, flash type, and energy characteristics during thunderstorm lifetime.  Lightning clusters of varying durations (ranging from <2 h to >12 h), seasons, and geographic regions (tropical or mid-latitude land) exhibit qualitatively similar evolutions of mean flash energy consistent with a shift toward stronger cloud-to-ground (CG) flashes later in the storm lifetime, which are more readily detected by WWLLN.  In contrast, preliminary results suggest that mean flash energy in clusters over the oceanic mid-latitude storm tracks or inter-tropical convergence zone (ITCZ) is largest at the beginning and end, and lowest in the middle of the cluster lifetime, suggesting land vs. ocean differences in convective processes controlling lightning type and energy.