We retrieve ionization rates in the atmosphere caused by energetic electron precipitation from balloon observations in the polar atmosphere and compare them against ionization rates recommended for the Phase 6 of the Coupled Model Intercomparison Project. In our retrieval procedure, we consider the precipitating electrons with energies from about tens of keV to 5 MeV. Our simulations with 1‐D radiative‐convective model with interactive neutral and ion chemistry show that the difference of the Phase 6 of the Coupled Model Intercomparison Project and balloon‐based ionization rate can lead to underestimation of the NO_x enhancement by more than 100% and ozone loss up to 25% in the mesosphere. The atmospheric response is different below 50 km due to considering highly energetic electrons, but it is not important because the absolute values of atmospheric impact is tiny. Ionization rates obtained from the balloon observations reveal a high variability.

We present a study of atmospheric electricity using the chemistry‐climate model SOCOL considering ionization by solar energetic particles during an extreme solar proton event (SPE), galactic cosmic rays (GCR), and terrestrial radon (Rn‐222). We calculate the global distribution of the atmospheric conductivity and fair‐weather downward current density (J_z) using atmospheric ionization rates from all sources. We found that J_z is enhanced (by more than 3.5 pA/m²) in radon source and polar regions. Contribution of Rn‐222 is essential at middle and low latitudes/altitudes where GCR‐induced air conductivity is reduced. The model results are in good agreement with the available observations. We also studied the effects of an extreme SPE, corresponding to the 774 AD event, on the atmospheric electricity and found that it would lead to a large increase of J_z on a global scale. The magnitude of the effects depends on location and can exceed background value more than 30 times over the high latitudes (a conservative upper bound). Such an assessment has been performed for the first time.

Recent years have seen increased attention given to radon from two scientific directions. After neglecting radon as an earthquake precursor in the 1990s, it has become the subject of discussions in earthquake-forecast papers due to growing networks of radon monitoring in different countries, particularly the technologies of real-time radon measurements where gamma spectrometers are of great interest as sources of ²²²Rn identification. The second fast-developing direction involves radon in Lithosphere–Atmosphere–Ionosphere Coupling (LAIC) models as a source of boundary layer ionization. Here we address the second topic, which is not connected with the earthquake forecast problems, namely, the role of air ionization by radon as a source of the Global Electric Circuit (GEC) modification. In this publication, we try to unite all of these problems to present a more complex view of radon as an important element in our environment. Special attention is paid to the dependence of radon variability on environmental conditions.

This paper examines the response of the upper atmosphere to increased radiation following exceptional solar activity in September 2017. The active region of the Sun AR2673 has caused intense solar-terrestrial disturbance. This active region has generated several powerful X-class solar flares. The strongest outburst of the 24th solar activity cycle X9.3 occurred on 6 September 2017. The second powerful solar flare X8.2 occurred on 10 September 2017. Both flares caused an increase of the solar irradiance in extreme ultraviolet and soft X-ray spectral regions, and Ly-$\alpha$ line. The empirical FISM2 model was used to obtain data on the radiation fluxes from solar flares. The HAMMONIA chemistry–climate model was used to analyze the effect of radiation on the neutral atmosphere. This work presents the results of the effect of solar flares on the chemical composition and ozone of the upper and middle atmosphere.