Relativistic electron precipitation (REP) refers to the release of high energy electrons initially trapped in the outer radiation belt that precipitate into the Earth’s upper atmosphere. REP plays an important role in the magnetosphere as it contributes to the fast depletion of radiation belt electron flux. This study presents a statistical analysis of the REP observations made by the Calorimetric Electron Telescope (CALET) experiment on board the International Space Station (2015- present). Specifically, a catalog based on count rates from the two top scintillators constituting the top charge detector, sensitive to electrons with energies $>$1.5 MeV and $>$3.4 MeV, respectively. Data from the CALET experiment reveals a previously unreported semi-annual variation in the occurrence of REP events. The REP periodicities are similar to those observed for trapped electrons in the outer belt, and correlates with the occurrence of solar wind high-speed streams and the solar cycle variations.

A document by Mykhaylo Shumko. Click on the document to view its contents.

Pitch Angle Distributions in the radiation belts are well characterized with sinnα. By tracking the exponent ‘n’, termed Pitch Angle Index, we are able to observe persistent and cross energy changes in pitch angle distributions of Van Allen radiation belt electrons using Van Allen Probes particle observations. The pitch angle distributions measurements are well fit down to a single satellite spin, and therefore can track spatially and temporally confined changes to determine connection between particles and waves. We use the Van Allen Probes data in conjunction with Geostationary Operational Environmental Satellites (GOES) spacecraft and several ground magnetometer stations from Canadian Array for Realtime Investigations of Magnetic Activity (CARISMA) and Finnish pulsation magnetometer network of Sodankylä Geophysical Observatory (SGO) to connect particles that become very anisotropic to electromagnetic ion cyclotron (EMIC) waves during a quiet period over two days, June 26 and 27, 2013. The waves and peaks in the particle PADs are both long lasting but spatially separated, suggesting that wave particle interactions in the inner magnetosphere can occur for extend periods of time and have significant impact on the global radiation belts, even during otherwise geomagnetically quiet times and when wave activity is highly localized.