Analysis of TGE-producing clouds using satellite data

Abstract

<p>Thunderstorm ground enhancement (TGE) is energetic radiation generated in electrified clouds and observed on the ground. The enhancement of flux of electrons and gamma-rays is accompanied by a variation of the electric field signifying the movement of an electrified cloud above the measurement point. The operation of the Aragats Research Station (Armenia, 40.47N, 44.18E, 3200 m above sea level) lead to the creation of a vast dataset on TGE parameters including meteorological conditions of its occurrence. The study of the energetic radiation of clouds is important for understanding the processes of interaction of energetic particles, the evolution of convective phenomena, microphysical processes, and charge separation in clouds.</p><p>The data on electric field and count rate measured in Aragats characterizing TGE events and data of satellite EUMETSAT–8 reveals correlations characterizing the convective patterns associated with TGEs. The source of the analyzed satellite data is SEVIRI (Spinning Enhanced Visible Infra-Red Imager) - an optical scanner operating in 12 spectral channels. The SEVIRI radiometer, installed on MSG satellites, has 12 channels that provide images of the Earth's surface every 15 minutes. The high-resolution channel in the visible range has a resolution of 1 km (for low latitudes), the other channels - 3 km. The frequency of updating satellite data is 15 minutes, which makes it possible to characterize in detail the dynamics of the development of convective phenomena.</p><p>The detected correlation between satellite data and data on particle fluxes for TGE events enables us to describe the probability of TGE occurrence by a new index based on a linear combination of measuring channels. The index characterizes the in-cloud conditions of TGE occurrence and is helpful for automatic analysis of measurement data and further development of TGE-forecasting systems.</p>