Quantifying the relative contributions of substorm injections and chorus waves to the rapid outward extension of electron radiation belt

Authors

Q. Zong
C A. Kletzing, University of IowaFollow
W. S. Kurth, University of IowaFollow
G. B. Hospodarsky, University of IowaFollow
Harlan E. Spence, University of New HampshireFollow
Geoffrey Reeves, Los Alamos National LaboratoryFollow
H. O. Funsten, Los Alamos National LaboratoryFollow
J. B. Blake, Aerospace CorporationFollow
D. N. Baker, University of Colorado BoulderFollow

Abstract

Abstract

We study the rapid outward extension of the electron radiation belt on a timescale of several hours during three events observed by Radiation Belt Storm Probes and Time History of Events and Macroscale Interactions during Substorms satellites and particularly quantify the contributions of substorm injections and chorus waves to the electron flux enhancement near the outer boundary of radiation belt. A comprehensive analysis including both observations and simulations is performed for the first event on 26 May 2013. The outer boundary of electron radiation belt moved from L = 5.5 to L > 6.07 over about 6 h, with up to 4 orders of magnitude enhancement in the 30 keV to 5 MeV electron fluxes at L = 6. The observations show that the substorm injection can cause 100% and 20% of the total subrelativistic (∼0.1 MeV) and relativistic (2-5 MeV) electron flux enhancements within a few minutes. The data-driven simulation supports that the strong chorus waves can yield 60%-80% of the total energetic (0.2-5.0 MeV) electron flux enhancement within about 6 h. Some simple analyses are further given for the other two events on 2 and 29 June 2013, in which the contributions of substorm injections and chorus waves are shown to be qualitatively comparable to those for the first event. These results clearly illustrate the respective importance of substorm injections and chorus waves for the evolution of radiation belt electrons at different energies on a relatively short timescale. Key Points Rapid outward extension of electron radiation belt observed by RBSP and THEMIS A two-step scenario to explain the rapid flux enchantment Differentiating between contributions of substorm injections and chorus waves.

Department

Physics

Publication Date

12-2014

Journal Title

Journal of Geophysical Research: Space Physics

Publisher

American Geophysical Union Publications

Digital Object Identifier (DOI)

10.1002/2014JA020709

Document Type

Article

Recommended Citation

Su, Z., et al. (2014), Quantifying the relative contributions of substorm injections and chorus waves to the rapid outward extension of electron radiation belt, J. Geophys. Res. Space Physics, 119, 10,023–10,040, doi:10.1002/2014JA020709.

Rights

©2014. American Geophysical Union. All Rights Reserved.