To effectively study loss due to precipitation of relativistic electrons in the radiation belt, it is necessary to isolate this loss by studying a time of relatively quiet geomagnetic activity. We present a case of initial enhancement and slow decay of 700 keV – 2 MeV electron populations in the outer radiation belt during an extended quiescent period from ~20 December 2012 – 13 January 2013. We incorporate particle measurements from the Colorado Student Space Weather Experiment (CSSWE) CubeSat and the Van Allen Probes twin spacecraft to understand the evolution of the electron populations across pitch angle and energy. Additional data from calculated phase space density (PSD), as well as hiss and chorus wave data from Van Allen Probes, helps complete the picture of the slow precipitation loss of relativistic electrons during quiet time. Electron loss to the atmosphere during this event is quantified through use of a precipitation loss model, utilizing CSSWE measurements at LEO, which offers a view into the loss cone that is not able to be resolved using only the Van Allen Probes. By comparing these results against equatorial Van Allen Probes electron flux data, we present the net precipitation loss of the outer radiation belt content to be greater than 92%, suggesting no significant acceleration during this period, and resulting in lower electron lifetimes (down to 2-3 days in the outer belt) for MeV electrons than have previously been reported inside the plasmasphere.
Co-authors: X. Li (LASP), Q. G. Schiller (LASP), L. W. Blum (LASP), W. Tu (Los Alamos), D. M. Malaspina (LASP), D. L. Turner (UCLA), B. Ni (UCLA), J. Bortnik (UCLA), D. N. Baker (LASP), S. G. Kanekal (NASA Goddard), J. B. Blake (Aerospace), and J. Wygant (Univ. of Minnesota)