Lightning Mapping Array and space-based optical observations of Narrow Bipolar Events

On 30 October 2018, about 20 lightning flashes were simultaneously observed from ground by means of the Colombia Lightning Mapping Array (Colombia-LMA) and from space by the optical photometers of the Atmosphere-Space Interactions Monitor (ASIM-MMIA). The initiations of four of these flashes exhibited typical features of fast breakdown and its associated NBE: intense VHF power emissions accompanied by VLF/LF bipolar sferics. These fast breakdown events were detected by ASIM-MMIA photometers as isolated blue (337.0 nm) optical pulses with absence, or very marginal, detections of red luminosity (777.4 nm). The analysis of the electrical charge structure of the storm and the direction of the currents of the sferics from by the measured magnetic field components, indicate that these cases correspond to fast positive breakdown (FNB). The dominance in the blue luminosity found in these events supports the streamer nature of the fast breakdown.