Scientific Motivation 2023

High-energy physics in the atmosphere (HEPA) has undergone an intense reformation in the last decade. Correlated measurements of particle fluxes modulated by strong atmospheric electric fields, simultaneous measurements of the disturbances of the near-surface electric fields and lightning location, and registration of various meteorological parameters on the Earth have led to a better understanding of the complex processes in the terrestrial atmosphere. The cooperation of cosmic rays and atmospheric physics has led to the development of models for the origin of particle bursts recorded on the Earth’s surface, estimation of vertical and horizontal profiles of electric fields in the lower atmosphere, recovery of electron and gamma ray energy spectra, the muon deceleration effect, etc. Visualization and statistical analysis of particle data from hundreds of measurement channels disclosed the structure and strength of the atmospheric electric fields and explained observed particle bursts. More and more groups worldwide are monitoring particle fluxes around the clock using synchronized networks of advanced sensors that record and store multidimensional data. 

Various particle accelerators operate in the cosmic plasma, filling the galaxy with high-energy particles. Reaching the Earth’s atmosphere, these particles cause 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 secondary particles and cause short and long particle bursts. Large amplifications of particle fluxes (the so-called thunderstorm ground enhancements (TGEs) manifest themselves as prominent peaks in the time series of count rates of particle detectors, coinciding with a strong atmospheric electric field accelerating and multiplying the free electrons of cosmic rays. Free electrons, abundant at any altitude in the atmosphere from the small to large EASs, serve as seeds for atmospheric electron accelerators, an analog of “electron guns” in artificial accelerators. EAS cores randomly hitting arrays of particle detectors generate short bursts of relativistic particles with a duration of fewer than 1 μs. Violent solar bursts fill the interplanetary space with immense magnetized plasma structures, moving up to 3000 km/s (the so-called interplanetary coronal mass ejection (ICME)) and perturbing the interplanetary magnetic field (IMF) and the magnetosphere. These disturbances could lead to major geomagnetic storms damaging multi-billion-dollar assets in space and on Earth. Monitoring the high-energy particles can provide highly cost-effective information also for predicting geomagnetic storms. For fundamental research in solar physics, solar–terrestrial relations, and space weather, as well as for forecasting the dangerous consequences of space storms, networks of particle detectors located in different geographical coordinates and measuring various types of secondary cosmic rays are of vital importance. Geophysical research is becoming increasingly important in the coming decades when natural disasters are rising. Solar, astrophysical, and atmospheric physics are synergistically linked and must be integrated to reveal the consequences of violent solar flares and extreme atmospheric electric fields. The synergy of high-energy space and atmospheric physics will open up new research areas for a better understanding and development of geospace physics. The new view of thunderclouds as media full of radiation can help to establish a comprehensive theory of cloud electrification and estimate the possible role of cloud radiation on climate change. The influence of the electrifying atmosphere on the fluxes of electrons and other charged particles can be significant for experiments registering very-high-energy photons (Atmospheric Cherenkov telescopes) or electrons and hadrons (Surface arrays registering Extensive Air Showers). The TEPA meeting provides an opportunity for scientists to discuss the current ideas and exploit synergies between Atmospheric and Cosmic ray physics.


We anticipate the following sessions:

  1. Multivariate observations of particles from the Earth’s surface, in the atmosphere,
and from space (TGEs, gamma glows, and TGFs);
        2. Remote sensing and modeling of the atmospheric electric field;
        3Correlated measurements of the atmospheric discharges, lightning flashes, and particle fluxes;
4. Space Weather and Solar physics with SEVAN network.
5. Influence of the atmospheric electric field on measurements of experiments using the atmosphere
as a target (Surface Arrays and Cherenkov Imaging Telescopes)

We also plan discussions on the most intriguing problems of high-energy physics in the atmosphere and possible directions for advancing collaborative studies.

Topics to be covered during oral and poster sessions:

  • Energy spectra of electrons and gamma rays measured on the earth’s surface, in the atmosphere,
and space; their relation to the strength of the electric field;
  • Possible links of the Solar activity and space weather to high-energy physics processes in the atmosphere;
  • Monitoring of lightning flashes by fast cameras
  • Radionuclide, neutron, and positron production during thunderstorms;
  • SEVAN particle detector network as a tool for the TGE research;
  • Methods of remote sensing of thundercloud charge structure and atmospheric electric fields;
  • Abrupt termination of the particle flux by the lightning flash;
  • Precise electronics for high-energy atmospheric research;
  • Relations to the climate and space weather issues;
  • Influence of the atmospheric electric fields on Extensive Air Shower (EAS) and Cherenkov light.
  • The possibility of joint observations by space-borne and ground-based facilities.