Radio frequency sensor: Very high frequency radio frequency lightning detection in geostationary orbit

The Radio Frequency Sensor (RFS), a new radio frequency lightning detector, was launched into geosynchronous orbit in December 2021, and first collected data in January 2022. RFS is a specialized software-defined radio receiver that detects, records, and reports impulsive broadband radio-frequency (RF) signatures from lightning in the very high frequency (VHF; 30–300 MHz) range. Its vantage point from a Western hemisphere geosynchronous orbit provides unique opportunities to study evolution of RF lightning signatures over the durations of thunderstorms over the Americas and Pacific Ocean. Its overlapping view with the Geostationary Lightning Mappers (GOES-16 & 17) enables additional comparisons between the sources of optical emissions and associated VHF emissions that were not possible with previous sensors. We find that RFS preferentially detects bright VHF signals called transionospheric pulse pairs (trans-ionospheric pulse pairs (TIPPs)). It is estimated that more than 85% of the RFS-detected lightning events are TIPPs. This paper presents initial results from the first year and a half of on-orbit operation.