Radiation belt electron acceleration during the 17 March 2015 geomagnetic storm: Observations and simulations
Abstract
Various physical processes are known to cause acceleration, loss, and transport of energetic electrons in the Earth's radiation belts, but their quantitative roles in different time and space need further investigation. During the largest storm over the past decade (17 March 2015), relativistic electrons experienced fairly rapid acceleration up to ~7 MeV within 2 days after an initial substantial dropout, as observed by Van Allen Probes. In the present paper, we evaluate the relative roles of various physical processes during the recovery phase of this large storm using a 3‐D diffusion simulation. By quantitatively comparing the observed and simulated electron evolution, we found that chorus plays a critical role in accelerating electrons up to several MeV near the developing peak location and produces characteristic flat‐top pitch angle distributions. By only including radial diffusion, the simulation underestimates the observed electron acceleration, while radial diffusion plays an important role in redistributing electrons and potentially accelerates them to even higher energies. Moreover, plasmaspheric hiss is found to provide efficient pitch angle scattering losses for hundreds of keV electrons, while its scattering effect on > 1 MeV electrons is relatively slow. Although an additional loss process is required to fully explain the overestimated electron fluxes at multi‐MeV, the combined physical processes of radial diffusion and pitch angle and energy diffusion by chorus and hiss reproduce the observed electron dynamics remarkably well, suggesting that quasi‐linear diffusion theory is reasonable to evaluate radiation belt electron dynamics during this big storm.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jun 01, 2016
- Source ID
- 10.1002/2016ja022400
Entities
People
- Craig Kletzing
- Daniel N. Baker
- Geoffrey D Reeves
- George G. Hospodarsky
- Harlan Spence
- J. B. Blake
- J. Bortnik
- J. C. Green
- Jiang Li
- Joel Goldstein
- Joseph F. Fennell
- Qianli Ma
- R. M. Thorne
- S. G. Kanekal
- V. Angelopoulos
- Wen Li
- William S. Kurth
- Xiao-Jia Zhang
Organizations
- Air Force Office of Scientific Research
- Goddard Space Flight Center
- Los Alamos National Laboratory
- National Aeronautics and Space Administration
- Southwest Research Institute
- The Aerospace Corporation
- University of California, Los Angeles
- University of Iowa
- University of New Hampshire
- University of Texas at San Antonio