Recent Advancements of Understanding of Relativistic Electrons in the Inner Belt

Xinlin Li, University of Colorado Boulder, Boulder, CO, United States, Richard Selesnick, Retired, Kirtland AFB, United States, Hong Zhao, Auburn University, Department of Physics, Auburn, United States, Daniel N Baker, University of Colorado, Laboratory for Atmospheric and Space Physics, Boulder, United States, Allison N Jaynes, University of Iowa, Iowa City, IA, United States, Shri Kanekal, NASA Goddard Space Flight Center, Greenbelt, MD, United States, Quintin A Schiller, University of Colorado at Boulder, Boulder, CO, United States, Lauren W Blum, University of California Berkeley, Berkeley, CA, United States, Joseph Fennell, Aerospace Corporation, Los Angeles, CA, United States and J Bernard Blake, The Aerospace Corporation, Los Angeles, CA, United States

Contact First Author: Xinlin Li; lix@lasp.colorado.edu

Previously Published Material: FALL AGU. Some of the results are to be published in JGR (just accepted)

Abstract ID#: 35476

 

English Abstract:
No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (10s of MeV to GeV). The inner belt proton flux level, however, is relatively stable, thus for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) on board Colorado Student Space Weather Experiment (CSSWE) CubeSat, in a low Earth orbit, clearly demonstrate that there exist sub-MeV electrons in the inner belt because of their flux level is orders of magnitude higher than the background, while higher energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Detailed analysis of high-quality measurements from the Relativistic Electron and Proton Telescope (REPT) and Magnetic Electron Ion Spectrometer (MagEIS) on board Van Allen Probes, in a geo-transfer-like orbit, provides, for the first time, detailed measurements of energetic electrons in both inner belt and outer belt, covering a wide energy range, from 10s of keV to multiple MeV. In this presentation, detailed pitch angle distribution of sub-MeV electrons from MagEIS measurements and quantified upper limits on multiple MeV electrons from REPT measurements will be discussed. These upper limits are rather different from flux levels in the AE8 and AE9 models, which were developed based on older data sources. For 1.7, 2.5, and 3.3 MeV electrons, the upper limits are about one order of magnitude lower than predicted model fluxes. The implication of this difference is profound in that unless there are extreme solar wind conditions, such as strong interplanetary shocks and coronal mass ejections, which have not happened yet since the launch of Van Allen Probes, enhancements of MeV electrons do not occur in the inner belt even though such enhancements are commonly seen in the outer belt.
Back to: Recent Multipoint Observations and Interpretation of Relativistic Electron Dynamics in the Earth's Radiation Belts