On the Global Occurrence and Impacts of Transient Luminous Events (TLEs)

Based on the first four years of the ISUAL (Imager of Sprites and Upper Atmospheric Lightning) experiment onboard the FORMOSAT‐2 satellite, ELVEs are found to be the most abundant type (∼80%) of TLEs (transient luminous events), whereas sprites and halos only combine to account for ∼20%. The distribution of sprites and halos closely resemble that of the cloud‐to‐ground lightning. However, nearly 60% of ELVEs occurred over the ocean, a feature indicating that the high peak current lightning is more abundant over the ocean. The global TLE occurrence rates are inferred to be 72, 3.7, and ∼1 events/minute, respectively, for ELVEs, halos, and sprites. Comparing with the results from the first three years of the ISUAL experiment reported by Chen et al. [1], the global occurrence rates for ELVEs and halos are higher due to the adoption of different correction factors. Using these updated TLE rates, the free electron content over an ELVE hot zone is estimated to be elevated by more than 10%. From analyzing ISUAL ...