Inner Belt Electron Decay Timescales: A Comparison of Van Allen Probes and DREAM3D Losses Following the June 2015 Storm
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- Los Alamos National Laboratory Los Alamos NM USA
- Astrophysical and Planetary Sciences Department University of Colorado Boulder CO USA, Laboratory for Atmospheric and Space Physics University of Colorado Boulder CO USA
- Department of Atmospheric and Oceanic Sciences University of California, Los Angeles Los Angeles CA USA
- CEA DAM DIF Arpajon France, UPS CEA LMCE Bruyères‐le‐Châtel France
Abstract NASA's Van Allen Probes observed significant, long‐lived fluxes of inner belt electrons up to ∼1 MeV after geomagnetic storms in March and June 2015. Reanalysis of Magnetic Electron Ion Spectrometer (MagEIS) data with improved background correction showed a clearer picture of the relativistic electron population that persisted through 2016 and into 2017 above the Fennell et al. (2015, https://doi.org/10.1002/2014gl062874 ) limit. The intensity and duration of these enhancements allow estimation of decay timescales for comparison with simulated decay rates and theoretical lifetimes. We compare decay timescales from these data and DREAM3D simulations based on them using geomagnetic activity‐dependent pitch angle diffusion coefficients derived from plasmapause‐indexed wave data (Malaspina et al., 2016, https://doi.org/10.1002/2016gl069982 , 2018, https://doi.org/10.1029/2018gl078564 ) and phase space densities derived from MagEIS observations. Simulated decay rates match observed decay rates more closely than the theoretical lifetime due to significantly nonequilibrium pitch angle distributions in simulation and data. We conclude that nonequilibrium effects, rather than a missing diffusion or loss process, account for observed short decay rates.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program; Defense Threat Reduction Agency (DTRA)
- Grant/Contract Number:
- 89233218CNA000001; 20200073DR; DTRA1308134079; DTRA1138125
- OSTI ID:
- 1974834
- Alternate ID(s):
- OSTI ID: 1974835; OSTI ID: 1975646
- Report Number(s):
- LA-UR-22-22470; e2022GL102106
- Journal Information:
- Geophysical Research Letters, Journal Name: Geophysical Research Letters Vol. 50 Journal Issue: 10; ISSN 0094-8276
- Publisher:
- American Geophysical Union (AGU)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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