Data from: Energetic radio emissions and possible terrestrial gamma-ray flashes associated with downward propagating negative leaders

A study of negative polarity energetic in-cloud pulses (—EIPs) during thunderstorms reveals that —EIPs occur during two distinct stages of downward negative leader development, and their similarity suggests that they are produced under similar ambient electric field conditions and by similar physical processes. The first group is composed of —EIPs observed at the beginning (less than 1 ms after initiation) of downward negative leaders. With an estimated average source altitude of ~5.9 km, these appear to be generated when the leader is still in the high field region between the main negative and lower positive charge layers inside thunderclouds. The second and newly reported group is observed at the very end of the downward negative leaders and spatially close to the first negative return stroke. These new —EIPs appear to be produced at low altitudes close to the ground where image charges amplify the electric field between the leader tip and conducting ground. Negative EIPs appear to occur only in these two scenarios, suggesting that they require a high background electric field to be produced. Positive EIPs, which produce similar radio emission signature with —EIPs and known to be connected to terrestrial gamma-ray flashes (TGF), are produced in association with a negative leader propagating in a high field region. We thus suggest that these two types of —EIPs may also be associated with downward TGFs.