Spatial Evolution of Energetic Electrons Affecting the Upper Atmosphere during the Last Two Solar Cycles

Abstract

Future commercial, scientific, and other satellite missions require low-Earth-orbit (LEO) altitudes of 300–400 km for long-term successful space operations. The Earth’s radiation belt (ERB) is an inevitable obstacle for manned and other space missions. Precipitation of >30 keV energetic electrons from the ERB is one of the sources of ionization in LEO, space vehicles, in the ionosphere, and in the upper atmosphere. We show, in this work, that the area of electron precipitation from the outer ERB shifts equator-wards to Siberia. We further show a substantive decrease in the intensity of energetic electrons in the area of the South Atlantic Anomaly (SAA) from the 23rd to the 24th solar cycles. These results can be attributed to, and explained by, variations in geomagnetic activity, with a noticeable change in the configuration of the Earth’s magnetic field during the 24th solar cycle. The diminishing SAA area and electron fluxes should allow elevation of the International Space Station to higher altitudes, thereby making these altitudes accessible to relevant space missions.

Solar-Cycle Variations of Forbidden Energetic Electrons Enhancements

“…This fact can be explained by an increase in the number of operating satellites from 4 to 6 (see Table 1) and by an increase in the number of single short-term (~15 min) FEE enhancements with a low intensity in the 24th solar cycle in comparison with the 23rd one-that is, injections of >30 keV electrons into the forbidden zone, although not so intense, continued even when solar wind drivers and, accordingly, geomagnetic activity weakened. The latter circumstance possibly indicates a change in the internal conditions associated with the Earth's magnetic field at low latitudes, as discussed in detail in [22,23].…”

Ionospheric Global and Regional Electron Contents in Solar Cycles 23–25

“…An important point is that the magnetic field is changing and the change influences the different processes forming the Earth's ionosphere [20], so this could result in a difference in REC/GEC dynamics in SC23/SC24/SC25. Magnetic field differences for these regions can cause rather different distributions of plasma (that we study by means of GEC and REC) due to anisotropy: plasma can move along magnetic field lines but not perpendicular to them.…”