Source: Journal of Geophysical Research: Atmospheres
The electric field and gamma ray enhancements at the surface of thunderstorm ground enhancements (TGEs) can be of positive or negative polarity. The cause of these enhancements is known to relate to the microphysical processes of cloud and precipitation particles within these storms. The mechanisms of the change in polarity, however, are not clear.
Williams et al.  use altitude-resolved S-band radar observations of graupel to demonstrate distinct differences in storm structure linked with “positive” and “negative” TGEs on Mount Aragats in Armenia. Their results show that shallow stages of convection are linked with “positive” TGEs, while deep stages of convection are linked with “negative” TGEs, consistent with the temperature-dependent electric tripole structure of thunderclouds.
This study reveals new insight into high-energy phenomena inside thunderclouds, by combining high-energy particle, electric-field, and radar observations.
Citation: Williams, E., Mkrtchyan, H., Mailyan, B., Karapetyan, G., & Hovakimyan, S. (2022). Radar Diagnosis of the Thundercloud Electron Accelerator. Journal of Geophysical Research: Atmospheres, 127, e2021JD035957. https://doi.org/10.1029/2021JD035957
—Minghua Zhang, Editor in Chief, Journal of Geophysical Research: Atmospheres