Types of lightning discharges that abruptly terminate enhanced fluxes of energetic radiation and particles observed at ground level

We present ground-based measurements of thunderstorm-related enhancements of fluxes of energetic radiation and particles that are abruptly terminated by lightning discharges. All measurements were performed at an altitude of 3200 m above sea level on Mount Aragats (Armenia). Lightning signatures were recorded using a wideband electric field measuring system with a useful frequency bandwidth of 50 Hz to 12 MHz and network of five electric field mills, three of which were installed at the Aragats station, one at the Nor Amberd station (12.8 km from Aragats), and one at the Yerevan station (39 km from Aragats). We observed that the flux-enhancement termination was associated only with close (within 10 km or so of the particle detector) negative CGs and normal-polarity ICs; that is, with lightning types which reduce the upward directed electric field below the cloud and hence suppress the acceleration of electrons toward the ground.