The electrons are from the solar wind and may remain trapped above Earth for an indefinite period of time (in some cases years).
[1] VLF waves traveling through the magnetosphere, caused by lightning or powerful transmitters, propagate through the radiation belt.
Groups of precipitated electrons can change the shape and conductivity of the ionosphere by colliding with atoms or molecules (usually oxygen- or nitrogen-based particles[4]) in the region.
EEP ozone depletion studies are important for monitoring the safety of Earth's environment[7] and variations in the solar cycle.
[6] Electron precipitation can be caused by VLF waves from powerful transmitter based communications and lightning storms.
When a bolt of lightning strikes the ground, an electromagnetic pulse (EMP) is released which can hit the trapped electrons in the radiation belt.
Occasionally, these waves will have the exact heading and frequency needed to cause an electron to precipitate from the radiation belt.
Scientists use superposed epoch analysis to take into account the strengths and weaknesses of a large set of different measurement methods.
The Global Ozone Monitoring by Occultation of Stars (GOMOS) is a measurement instrument aboard the European satellite Envisat.
It measures ozone amounts by using the emitted electromagnetic spectrum from surrounding stars combined with trigonometric calculations in a process called stellar occultation.
[6] The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) is a measurement instrument aboard NASA's Thermal Ionosphere Mesosphere Energetics Dynamics (TIMED) satellite.
PIPER is a Stanford-made photometer specifically designed for capturing the photons emitted when ionization occurs in the ionosphere.
James Van Allen from the State University of Iowa with his group, were the first to use vehicles with sensors to study electron fluxes precipitating in the atmosphere with rockoon rockets.