A Method to Retrieve Charge Layer Polarity Applied to Anomalous Thunderstorms in Cordoba During the RELAMPAGO Field Campaign

The RELAMPAGO (Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations) Project, conducted in the Argentinian province of Cordoba in 2018, aimed to study thunderstorms that rapidly grow upscale and produce amongst the highest flash rates thunderstorms in the world. Multiple radars, lightning networks and soundings were deployed during the austral spring months of November and December 2018. Two lightning instrumentations were deployed by The University of Alabama in Huntsville and the NASA Marshall Space Flight Center. Eleven VHF Lightning Mapping Array (LMA) sensors were installed with an average baseline of 30 km, and 10 LF/VLF Cordoba Argentina Marx Meter Array (CAMMA) sensors were installed in roughly the same locations. An automated method to determine regions of charge within thunderstorms is proposed using LMA time-of-arrival located sources. The method consists in determining the flash's initial leader (preliminary breakdown, PB) vertical displacement, assuming it as a negative leader. A polarity is determined for each non-preliminary breakdown sources above and below the initial PB height, in which the polarity depends on the initial PB vertical trend. The charge regions retrieved using the automated method for multiple anomalous charge structure thunderstorms will be presented, which is defined as any thunderstorm with charge structure other than having an upper positive, mid-level negative, and lower positive charge layers. The efficiency of the algorithm will be obtained by comparing it with a manual determination of source polarity using LMA and CAMMA source locations for all flashes that occurred during a period of tens of minutes. CAMMA electric field change waveforms will be used to help interpret the polarity of leaders. The percentage of anomalous charge structure thunderstorms, and anomalous days will be presented. Also, the comparison of the automated method with the manual analysis will show the reliability of the algorithm, which has potential for fast depiction of thunderstorms charge structure, and can be useful for numerous applications in lightning research.