Earths Radiation Belt

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Earths Radiation Belt

• Xi Shao
• Department of Astronomy,
• University Of Maryland, College Park, MD 20742

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Outline

• History and importance of studying Earths
  radiation belt
• Dynamics of Earths radiation belt Observations
• Origin of Earths radiation belt Geomagnetic
  Storms and Substorms.
• Modeling formation of Earths radiation belt.
• Slot Region formation.

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Radiation Belts The Big Picture

• The Radiation Belt is a energetic torus of
  energetic charged particles (plasma) around
  Earth, held in place by Earth's magnetic field
• Historic discovery in 1958 by the Explorer I in
  1958, and Explorer III missions, under Dr.James
  Van Allen at the University of Iowa.
• The trapped radiation was first mapped out by
  Sputnik 3, Explorer IV, Pioneer III and Luna 1.
• Energetic electrons form two distinct radiation
  belts, while protons form a single belt.

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The Radiation Belts Today a Dynamic Space
Weather Environment

• Space Weather Applications
• Astronauts safety
• Hardware integrity
• Mission performance
• Satellite solar cell panel degradation
• Single Event Upset (SEU)

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The Radiation Belts Today a Dynamic Space
Weather Environment
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Why Trapped?
Proton Orbit
Electron Orbit
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NOAA POES Observations-Dynamical View
Orbit Altitude 800 km Inclination 98
degree Orbit Period 100 mins MEPED Detector
Energy Channels used in this poster Proton gt80
MeV (Omni-Detector) Electron gt 300
keV (Omni-Directional flux derived from 2
telescopes)
NOAA POES Data obtained from http//poes.ngdc.noaa
.gov
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NOAA POES Satellite Oribit
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Electron (gt 300 keV) Belt Dynamics (1979-1991)
Outer Belt Weakens
Mar. 1991
Mar. 1989
Feb. 1986
Jul. 1982
Apr. 1981
Inner belt Enhanced
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Electron (gt 300 keV) Belt Dynamics (1992-2004)
Outer Belt Weakens
Oct-Nov, 2003
Inner belt Re-Enhanced
NOAA-15 changes telescope pointing direction and
data is still in processing for L lt 2.
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Radiation Belt Dynamics and Geomagnetic Storms
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Proton (gt 80 MeV) Belt Dynamics (1979-1991)
Mar. 1991
Mar. 1989
Feb. 1986
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Proton (gt 80 MeV) Belt Dynamics (1992-2004)
Oct-Nov, 2003
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Radiation Belt inside the Earths Magnetosphere
Its Origin.
Earths Magnetosphere
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Modeling Solar Wind Interaction with Earths
Magnetosphere
MHD Equations Solved on a 3D Stretched Spherical
Mesh
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Magnetospheric Storms/Substorms
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Vortices During 2002-03-29 Event
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Complex Vortices Structure inside Magnetosphere
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Magnetospheric Substorm
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Mid-Tail Reconnection
t 00-07-48
t 004720
t 005105
t 005606
t 010107
t 010608
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Development of Bursty Bulk Flow
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Ring Current Development
100 UT
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Physical Modeling of Radiation Belt
3D Electric-Magnetic field from LFM Global MHD
Model of Earths Magnetosphere
Initial Test Particle Distribution
3D Particle Tracing Code (Full Motion
for Protons, and Guiding Center for electrons)
e
RB energetic particle distribution
p
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Radiation Belt Electron Dynamics
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Radiation Belt Protons Dynamics
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Energization of Radiation Belt Electrons
Initial Configuration of 5keV electrons
A snapshot of electron location and energy in 3D
10 mins later
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Formation of Slot Region in Electron Radiation
Belt
Whistler Waves in the Plasmasphere
Slot Region
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Quick Time Movie
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Solar Cycle Shifting of Safe-Zone
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Summary

• Review History and Importance of Radiation Belt
• Radiation Belt Structure
• Origin of Radiation Belt
• Radiation Belt Slot region
• Safe-zone Solar-Cycle Shifting.

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Outstanding science questions

• Acceleration mechanisms
• their relative significance
• Solar wind-inner magnetosphere coupling
• Loss mechanisms
• User needs a Model
• Accurate flux models
• L shell specificity
• Forensic evaluation
• Nowcasting