Solar Cycle Dependence of 2-6 MeV Electrons

1
Radiation Belt Electron
Transport Energization
Slot region
outer belt
inner belt
Mary K. Hudson, Magnetospheric
Thrust Participants
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Coupled Modeling Scheme
3
Solar Cycle of SAMPEX 2-6 MeV Electrons
Li et al., GRL, 2006
4
Response to Solar Wind Forcing

• 2-3 day lag at Geo
• Paulikas Blake, 1979
• Prompt peak L 3
• Vassiliadis et al., 2003

SAMPEX/Vsw correlation
2-6 MeV fluxes
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ULF Wave-Relativistic Electron Correlation
Rostoker et al., GRL, 1998
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Direct Coupling of Solar Wind ULF Waves
Kepko Spence, JGR, 2003
Or Convective Growth Magnetopause K-H Waves
Miura, JGR, 1992 Claudepierre et al., JGR,
2008 LFM time series analysis
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Halloween 03 2-6 and gt10 MeV Electrons
See filling of slot region on storm timescale
(days) at 2-6 MeV (Baker et al., 2004)
SAMPEX observes gt 2 month delay in high gt 10 MeV
fluxes at low altitude (longer loss time)
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Halloween 03 Shock Injection
LFM-test particle simulation

• W 5 MeV ? 15 MeV
• R 6 RE ? 2.5 RE

??E - ?B/?t ?Bz/?t ? E?
Kress et al., JGR, 07
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Halloween 03 Shock Injection of gt10 MeV (W01-7
MeV) Electrons
Kress et al., 2006
10

• Low altitude SAMPEX observations at gt 10 MeV
  electrons, injected 10/29/03 Looper et al., 06

Simulated pitch angle distribution-gt
Kress et al., 2006
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MHD Fields Inject RadBelt Electrons
Plasmasheet el injection ?
Elkington et al., JASTP, 2004
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MHD Fields Injection of RadBelt Electrons
Elkington et al., JASTP, 2004
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PSD calculations for other storms
January 1995
September 1998 (final)

• The (big) September 1998 storm shows a
  significant change in trapped PSD as a result of
  coupling to the plasmasheet.
• The more moderate storm of January 1995 showed
  almost no coupling with the plasmasheet.

Elkington et al., 2008
14
Diffusion Rates vs. L

• Radial diffusion rates in model ULF wave fields
• D_LL LN
• Perry et al., JGR, 05, includes dEf, dBr, dB//,
  freq and L-dependent power

Radial diffusion rates in model ULF wave
fields DLL D0LN


ULF wave DLL studies Elkington et al.,
2003 Ukhorskiy et al., 2005 Fei et al., 2006
Tau(L,E) Summers 04 Tau days/Kp Shprits 05
Braughtigam Albert, 2000, N 10 Perry et al.,
2006
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F. Chu et al., AGU, F 07

• 1000 MeV/G

?
Radial Diffusion for Nov 04 Storm
Baker et al., GRL, 07
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July Nov 04 Differ by SSC

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Plasmapause Control of Electron Flux Peak and
Slot Region
Local accel and pitchangle scattering due to
VLF/ELF waves (Whistler, EMIC)
Shprits et al., JASTP 2008
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Magnetospheric SEP Simulations
SEP Cutoffs Brian Kress poster
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(No Transcript)
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SEP Cutoff rigidities calculated in a CISM CMIT
simulation of 14 May 1997 storm
IGRF field embedded within MHD inner boundary
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Handoff to Forecast Transition

• Radial diffusion model with DLLdetermined by LTR
  ULF wave power tabulated by vsw or Kp switch
• SEP cutoffs in solar-wind parametrized MHD field
  snapshots
• Neither involve pushing millions of particles in
  time-dependent MHD fields in real time using
  appropriate input spectra
• Given input spectra, e.g. SEPs from
  COHRELparametrized shock model ?SEP cutoffs
• Given continuously available geo fluxes? radbelt
  f at peak flux, typically L3-4 at 2-6 MeV,
  determined from radial diffusion code including
• time-dependent plasmapause loss term