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CISM Radiation Belt Models

CISM Radiation Belt Models. CMIT. Mary Hudson CISM Seminar Nov 06. Van Allen Radiation Belts. Slot region. outer belt. inner belt. Van Allen Belts-Plasmasphere Overlap. Ring current. Solar Cycle Dependence of 2-6 MeV Electrons. Li et al., GRL, 2006.

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CISM Radiation Belt Models

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  1. CISM Radiation Belt Models CMIT Mary Hudson CISM Seminar Nov 06

  2. Van Allen Radiation Belts Slot region outer belt inner belt

  3. Van Allen Belts-Plasmasphere Overlap Ring current

  4. Solar Cycle Dependence of 2-6 MeV Electrons Li et al., GRL, 2006

  5. 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

  6. Effect on the Radiation Belts [Baker et al., 2004, Nature] slot region new belt

  7. March 91 Shock Acceleration 3.5 MeV at L=6.6, t=0 (M =11,150 MeV/G) Elkington et al., JASTP, 02; 04

  8. MHD-Guiding Center Simulation Elkington et al., JASTP, 2002; 2004

  9. SAMPEX >10 MeV Electron Injections

  10. SAMPEX: Mar 91 decay+Feb 94 injection

  11. Halloween 03 >10 MeV Electron Injections

  12. Ideal MHD equations are solved on a computational grid to simulate the response of the magnetosphere Global LFM-MHD Simulations of Magnetosphere • Solar wind measurements made WIND, ACE or IMP8 (Feb 94, not Mar 91)

  13. 1994 Feb 21 Event: density

  14. 1994 Feb 21 Event: Ephi

  15. Halloween ’03 Shock Injection initialE ~ 5 MeV, R ~ 6 RE, final E ~15 MeV, R ~ 2.5 RE Kress et al., 06

  16. Halloween ’03 Shock Injection of >10 MeV (W0=1-7 MeV) Electrons

  17. E_phi (left) and Solar Energetic Electron Trajectory (right) Halloween ‘03 solar energetic electron injection event Kress et al., 2006

  18. Low altitude SAMPEX observations of > 10 MeV electrons, injected 10/29/03 • E-1.5 electron energy spectrum from several MeV to > 15 MeV • Initially not observed at SAMPEX due to eq injection Simulated pitch angle distribution->

  19. Outer Belt Losses Due to Whistler Pitch Angle Scattering outer belt Whistler Mode Hiss 2-6 MeV Slot Variability: [Lyons et al., 1972]

  20. Losses due to Pitch Angle Scattering EMIC waves from ring current ions VLF waves from p’sheet electrons

  21. MHD Fields Injection of RadBelt Electrons Elkington et al., JASTP, 2004

  22. MHD Fields Injection of RadBelt Electrons Elkington et al., JASTP, 2004

  23. Diffusion Rates vs. L Radial diffusion rates in model ULF wave fields D_LL ~ LN Perry et al., JGR, 05, includes δEφ, δBr, δB//, freq and L-dependent power • Radial diffusion rates in • model ULF wave fields • D_LL ~ L^N • Perry et al., JGR, 2005, • Include δEφ, δBr, δB//, • freq and L-dependence • 3D trajectories • N ~ 6 for no L-dep power, N ~ 12 with L dependence • M=273 MeV/G # # # # Selesnick & Blake 2000 # Tau(L,E) Summers 04 Elkington et al., 2003 Braughtigam & Albert, 2000, N=6, 10; Perry et al., 2006, N=6, 12

  24. 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 DLL=10-2(L/4)^12 day-1 Dashed lines show CRRES measurements of PSD 61 days apart. Loss model based on Summers et al. 2004.

  25. MHD-Driven Phase Space Density Radial Diffusion MHD-Test Particle AE8 Max-Initialized, Sept 98 Storm Fei et al., 2006

  26. New belt example: 24 Nov 2001 Clear trapping of solar particles: 13 of 26 SEP penetration events inside L=4, 98-03 Mazur et al., AGU Monograph 165, 2006

  27. 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 m’sphere during IMF Bz<0

  28. Drift Time Scale Injection from SSC’s Blake et al., 2005

  29. Mar 91-Feb 91Comparison

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