Comparing lightning Superbolts detected independently in the optical and VLF ranges

This study investigates the phenomenon of “Superbolts”, High-intensity lightning flashes – by examining their occurrence and correlations across multiple lightning monitoring networks. Given inconsistencies in Superbolt definitions in prior research, this study addresses the feasibility of establishing a universal definition for Superbolts and analyzes the inherent challenges to do so.

 

A statistical methodology was used to study Superbolts occurrence across three datasets: the ISS Lightning Imaging Sensor (LIS), the World-Wide Lightning Localization Network (WWLLN), and the Earth Networks Total Lightning Networks (ENTLN). This study employed current peak power and energy thresholds to propose statistical-based thresholds for Superbolts radiance and used spatial and temporal matching criteria to examine the correlation between the occurrence of Superbolts in different detection methods.

 

This study identified notable divergences between spatial and temporal distributions of Superbolts across different systems. Both LIS and WWLLN datasets show high-density regions of superbolts over the Maritime Continent of Asia, South America, and South Africa, but disparities appear around Australia, Central America, and northern regions. Moreover, temporal analysis shows a seasonal dependency, with LIS data indicating higher Superbolt incidence in summer, contrasting with WWLLN's peak during winter. While WWLLN data partially align with Kirkland's "three Superbolt chimneys" (1999), the observed high-density regions differ substantially from those presented in Holzworth et al. (2019). Correlation analysis between ENTLN and LIS datasets showed insignificant matching in Superbolts occurrence.

 

These findings underscore the inherent challenges to establish a universal definition for Superbolts, especially when comparing data from optical-based and RF-based monitoring networks. Challenges include differences in temporal and spatial coverage, detection biases due to atmospheric conditions, and non-unique matching of flashes. Hence, system-specific or statistical based thresholds may provide a more feasible alternative. Future research should include meteorological data, such as clouds cover and optical-depth, and explore the relationships between global lightning distribution and Superbolts formation.