Transcript CISM Radiation Belt Models CMIT Mary Hudson CISM Seminar Nov 06 Van Allen Radiation Belts Slot region outer belt inner belt.

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
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
Effect on the Radiation Belts
[Baker et al., 2004, Nature]
slot region
new belt
March 91 Shock Acceleration
3.5 MeV at L=6.6, t=0 (M =11,150 MeV/G)
MHD-Guiding Center Simulation
Elkington et al., JASTP, 2002; 2004
SAMPEX >10 MeV Electron
Injections
SAMPEX: Mar 91 decay+Feb 94 injection
Halloween 03 >10 MeV Electron
Injections
Global LFM-MHD Simulations
of Magnetosphere
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Solar wind
measurements made
WIND, ACE or IMP8
(Feb 94, not Mar 91)
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Ideal MHD equations
are solved on a
computational grid to
simulate the response
of the magnetosphere
1994 Feb 21 Event: density
1994 Feb 21 Event: Ephi
Halloween ’03 Shock Injection
initial E ~ 5 MeV, R ~ 6 RE,
final E ~15 MeV, R ~ 2.5 RE
Kress et al., 06
Halloween ’03 Shock Injection of >10
MeV (W0=1-7 MeV) Electrons
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 > 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->
Outer Belt Losses Due to Whistler Pitch Angle Scattering
outer
belt
2-6 MeV
Slot Variability:
[Lyons et al., 1972]
Hiss
Whistler
Mode
Losses due to Pitch Angle
Scattering
EMIC waves
from ring
current ions
VLF waves
from p’sheet
electrons
MHD Fields Injection of RadBelt
Electrons
Elkington et al., JASTP, 2004
MHD Fields Injection of RadBelt
Electrons
Elkington et al., JASTP, 2004
Diffusion Rates vs. L
Radial diffusion
rates in model
ULF wave fields ###
# Selesnick &
Blake 2000LN
D_LL ~
#
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
Tau(L,E) Summers 04
Elkington et al., 2003
Braughtigam & Albert, 2000, N=6, 10; Perry et al., 2006, N=6, 12
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.
MHD-Driven Phase Space Density
Radial Diffusion
MHD-Test Particle
AE8 Max-Initialized, Sept 98 Storm
Fei et al., 2006
New belt example: 24 Nov 2001
Mazur et al., AGU
Monograph 165, 2006
Clear trapping of solar particles: 13 of 26
SEP penetration events inside L=4, 98-03
Conclusions
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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
Drift Time Scale Injection from SSC’s
Blake et al., 2005
Mar 91-Feb 91Comparison