CISM Radiation Belt Models

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CISM Radiation Belt Models
CMIT
Mary Hudson CISM Seminar Nov 06
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Van Allen Radiation Belts
Slot region
outer belt
inner belt
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Van Allen Belts-Plasmasphere Overlap
Ring current
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Solar Cycle Dependence of 2-6 MeV Electrons
Li et al., GRL, 2006
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Van Allen Radiation Belts Slot region variability
Slot region
outer belt
inner belt
SAMPEX electrons 2 - 6 MeV
Outer belt
slot region L 2 - 3
inner belt
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Effect on the Radiation Belts
Baker et al., 2004, Nature
slot region
new belt
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March 91 Shock Acceleration
3.5 MeV at L6.6, t0 (M 11,150 MeV/G)
Elkington et al., JASTP, 02 04
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MHD-Guiding Center Simulation
Elkington et al., JASTP, 2002 2004
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SAMPEX gt10 MeV Electron Injections
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SAMPEX Mar 91 decayFeb 94 injection
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Halloween 03 gt10 MeV Electron Injections
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Global LFM-MHD Simulations of Magnetosphere

• Solar wind measurements made WIND, ACE or IMP8
  (Feb 94, not Mar 91)

• Ideal MHD equations are solved on a computational
  grid to simulate the response of the
  magnetosphere

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1994 Feb 21 Event density
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1994 Feb 21 Event Ephi
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Halloween 03 Shock Injection initial E 5 MeV,
R 6 RE, final E 15 MeV, R 2.5 RE
Kress et al., 06
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Halloween 03 Shock Injection of gt10 MeV (W01-7
MeV) Electrons
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E_phi (left) and Solar Energetic Electron
Trajectory (right)
Halloween 03 solar energetic electron injection
event Kress et al., 2006
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• Low altitude SAMPEX observations of gt 10 MeV
  electrons, injected 10/29/03
• E-1.5 electron energy spectrum from several MeV
  to gt 15 MeV
• Initially not observed at SAMPEX due to eq
  injection

Simulated pitch angle distribution-gt
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Outer Belt Losses Due to Whistler Pitch Angle
Scattering
outer belt
Whistler Mode
Hiss
2-6 MeV Slot Variability Lyons et al., 1972
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Losses due to Pitch Angle Scattering
EMIC waves from ring current ions
VLF waves from psheet electrons
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MHD Fields Injection of RadBelt Electrons
Elkington et al., JASTP, 2004
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MHD Fields Injection of RadBelt Electrons
Elkington et al., JASTP, 2004
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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 D_LL LN Perry et al., JGR, 2005,
Include dEf, dBr, dB//, freq and L-dependence
3D trajectories N 6 for no L-dep power, N 12
with L dependence M273 MeV/G



Selesnick Blake 2000

Tau(L,E) Summers 04
Elkington et al., 2003
Braughtigam Albert, 2000, N6, 10 Perry et
al., 2006, N6, 12
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Solutions to diffusion equation using DLL from
model ULF wave fields and PSD from CRRES
measurements in subsequent 10-hr orbits to update
inner and outer boundaries
Perry et al. 2005 DLL10-2(L/4)12 day-1
Dashed lines show CRRES measurements of PSD 61
days apart. Loss model based on Summers et al.
2004.
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MHD-Driven Phase Space Density
Radial Diffusion
MHD-Test Particle
AE8 Max-Initialized, Sept 98 Storm
Fei et al., 2006
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New belt example 24 Nov 2001
Clear trapping of solar particles 13 of 26 SEP
penetration events inside L4, 98-03
Mazur et al., AGU Monograph 165, 2006
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Conclusions

• Drift time scale injection of multi- MeV
  electrons Strong compression of dayside
  magnetopause due to high speed CME
• Relativistic electron seed population at and
  beyond geosynchronous required
• Plasmasphere plays role intensifying E_phi
• Long-lived, energetic trapped population injected
  into slot region
• Well-described by CMIT without coupled RCM
• Intermediate storm timescale (hrs,days) changes
  in PSD described by radial diffusion loss due
  to whistler (and EMIC) scattering
• Enhanced D_LL due to ULF waves needs further
  study with RCM coupled to CMIT, plasmasphere, ion
  outflow to populate msphere during IMF Bzlt0

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Drift Time Scale Injection from SSCs
Blake et al., 2005
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Mar 91-Feb 91Comparison