Effect of EMIC waves on relativistic and ultrarelativistic electron populations: Ground-based and Van Allen Probes observations

Authors

M. Usanova, University of Alberta
A. Drozdov, University of California - Los Angeles
K. Orlova, University of California - Los Angeles
I. R. Mann, University of AlbertaFollow
Y. Y. Shprits, University of California - Los Angeles
M. T. Robertson, University of Alberta
D. L. Turner, University of California - Los AngelesFollow
D. K. Milling, University of Alberta
A. Kale, University of Alberta
D. N. Baker, University of Colorado BoulderFollow
S. A. Thaller, University of Minnesota - Twin CitiesFollow
Geoffrey Reeves, Los Alamos National LaboratoryFollow
Harlan E. Spence, University of New HampshireFollow
C A. Kletzing, University of IowaFollow
J. R. Wygant, University of Minnesota - Twin Cities

Abstract

Abstract

We study the effect of electromagnetic ion cyclotron (EMIC) waves on the loss and pitch angle scattering of relativistic and ultrarelativistic electrons during the recovery phase of a moderate geomagnetic storm on 11 October 2012. The EMIC wave activity was observed in situ on the Van Allen Probes and conjugately on the ground across the Canadian Array for Real-time Investigations of Magnetic Activity throughout an extended 18 h interval. However, neither enhanced precipitation of >0.7 MeV electrons nor reductions in Van Allen Probe 90° pitch angle ultrarelativistic electron flux were observed. Computed radiation belt electron pitch angle diffusion rates demonstrate that rapid pitch angle diffusion is confined to low pitch angles and cannot reach 90°. For the first time, from both observational and modeling perspectives, we show evidence of EMIC waves triggering ultrarelativistic (~2-8 MeV) electron loss but which is confined to pitch angles below around 45° and not affecting the core distribution. Key Points EMIC wave activity is not associated with precipitation of MeV electrons EMIC waves do not deplete the ultra-relativistic belt down to 90° EMIC waves cause loss of low pitch angle electrons with energies ~2-8 MeV.

Department

Physics

Publication Date

3-2014

Journal Title

Geophysical Research Letters

Publisher

American Geophysical Union Publications

Digital Object Identifier (DOI)

10.1002/2013GL059024

Document Type

Article

Recommended Citation

Usanova, M. E., et al. (2014), Effect of EMIC waves on relativistic and ultrare-lativistic electron populations: Ground-based and Van Allen Probes observations, Geophys. Res. Lett., 41, 1375–1381, doi:10.1002/2013GL059024.

Rights

©2014. American Geophysical Union. All Rights Reserved.