How do the strongest radio pulses from thunderstorms relate to lightning flashes? art. no. 4778

We present a statistical analysis of thunderstorm radio frequency and optical data from the FORTE satellite to examine the relationship of strong radio frequency pulsed emissions to more conventional signals from lightning. The study is built on a FORTE database of intracloud pulsed radio signals from storms whose geolocation is provided either by coincidence with the FORTE optical imager or by coincidence with ground-based lightning-detection arrays. We show statistically that intracloud radio emissions with peak power >40 kW in the FORTE low band (26-48 MHz) have unique characteristics compared to weaker emissions, including: occurring either in isolation or at the start of leader progression but never within a progressing leader; occurring without light emission detectable by FORTE; sometimes occurring in association with a rapid (10 mus) relaxation of the electric charge; and being followed by an upward progressing leader in the cases where a leader is initiated. These strong intracloud radio pulses appear to be associated with an intracloud discharge process that is physically distinct from conventional leader progression.