Extensive air showers and atmospheric electric fields. Synergy of space and atmospheric particle accelerators

Abstract

Various particle accelerators operate in the space plasmas, filling the Galaxy with high-energy particles (primary cosmic rays). Reaching the Earth's atmosphere, these particles originate extensive air showers (EASs) consisting of millions of elementary particles (secondary cosmic rays), covering several km2 on the ground. During thunderstorms, strong electric fields modulate the energy spectra of EAS secondary particles, changing the shower size (number of EAS electrons) and altering the primary particle's estimated energy and frequency of the surface array triggers. Impulse amplifications of particle fluxes (the so-called thunderstorm ground enhancements, TGEs) manifest themselves as large peaks in the time series of count rates of particle detectors located on the Earth’s surface. Free electrons are abundant at any altitude in the atmosphere, from small to large EASs. These electrons serve as seeds for electron accelerators, which operate in the thunderous atmosphere and send particle avalanches in the direction of Earth's surface and into space (terrestrial gamma flashes, TGFs). EAS cores randomly hitting arrays of particle detectors also generate short bursts of relativistic particles. For years, particle detectors, electric field sensors, and lightning locators have gathered information about the complex interactions of secondary particle fluxes, electric fields, and lightning flashes. This information is crucial for establishing a field of high-energy physics in the atmosphere. Plain language summaryCorrelated measurements of particle fluxes modulated by strong atmospheric electric fields, registration of broadband radio and optical emission from atmospheric discharges, and registration of electric fields and various meteorological parameters lead to a better understanding of the complex processes of particle-field interactions in the terrestrial atmosphere. The cooperation of cosmic rays and atmospheric physics has led to the development of models of the origin of particle bursts recorded on the Earth's surface, vertical and horizontal profiles of electric fields, initiation of lightning flashes, etc. Interdisciplinary atmospheric science primarily requires monitoring particle fluxes around the clock by synchronized networks of identical sensors that record and store multidimensional data in databases with open, fast, and reliable access. The advances in multidimensional measurements over the past decade significantly intensified the development of new integrated models of atmospheric electricity and electron acceleration, giving more insight into understanding the modulation effects posed on EAS particles in the strong atmospheric electric fields.