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Space Plasma Physics. Earth’s Radiation Belt. Xi Shao Department of Astronomy, University Of Maryland, College Park, MD 20742. Space Plasma Physics. Outline. History and importance of studying Earth’s radiation belt Dynamics of Earth’s radiation belt: Observations

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Earth’s Radiation Belt

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Space Plasma Physics

Earth’s Radiation Belt

Xi Shao

Department of Astronomy,

University Of Maryland, College Park, MD 20742


Space Plasma Physics

Outline

  • History and importance of studying Earth’s radiation belt

  • Dynamics of Earth’s radiation belt: Observations

  • Origin of Earth’s radiation belt: Geomagnetic Storms and Substorms.

  • Modeling formation of Earth’s radiation belt.

  • Slot Region formation.


Radiation Belts: The Big Picture

Explorer I

Space Plasma Physics

  • 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.


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)


The Radiation Belts Today:

a Dynamic Space Weather Environment


Why Trapped?

Proton Orbit

Electron Orbit


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: >80 MeV

(Omni-Detector)

Electron: > 300 keV

(Omni-Directional flux derived from 2 telescopes)

NOAA POES Data obtained from

http://poes.ngdc.noaa.gov


NOAA POES Satellite Oribit


Electron (> 300 keV) Belt Dynamics

(1979-1991)

Outer Belt

Weakens

Mar. 1991

Mar. 1989

Feb. 1986

Jul. 1982

Apr. 1981

Inner belt

Enhanced


Electron (> 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 < 2.


Radiation Belt Dynamics and Geomagnetic Storms


Proton (> 80 MeV) Belt Dynamics

(1979-1991)

Mar. 1991

Mar. 1989

Feb. 1986


Proton (> 80 MeV) Belt Dynamics

(1992-2004)

Oct-Nov, 2003


Radiation Belt inside the Earth’s Magnetosphere: Its Origin.

Earth’s Magnetosphere


Space Plasma Physics

Modeling Solar Wind Interaction with Earth’s Magnetosphere

MHD Equations Solved on a 3D Stretched Spherical Mesh


Space Plasma Physics

Magnetospheric Storms/Substorms


Vortices During 2002-03-29 Event


Complex Vortices Structure inside Magnetosphere


Space Plasma Physics

  • Magnetospheric Substorm


Mid-Tail Reconnection

t= 00:-07:-48

t= 00:47:20

t= 00:51:05

t= 00:56:06

t= 01:01:07

t= 01:06:08


Development of Bursty Bulk Flow


Space Plasma Physics

Ring Current Development

1:00 UT


Space Plasma Physics

Physical Modeling of Radiation Belt

3D Electric-Magnetic

field from LFM Global

MHD Model of

Earth’s Magnetosphere

Initial Test Particle

Distribution

3D Particle Tracing

Code (Full Motion for

Protons, and Guiding

Center for electrons)

e

RB energetic

particle distribution

p


Radiation Belt Electron Dynamics


Radiation Belt Protons Dynamics


Energization of Radiation Belt Electrons

Initial Configuration of 5keV electrons

A snapshot of electron location and energy in 3D10 mins later


Formation of Slot Region in Electron Radiation Belt

Whistler Waves in the

Plasmasphere

Slot Region


Quick Time Movie


Solar Cycle Shifting of Safe-Zone


Summary

  • Review History and Importance of Radiation Belt

  • Radiation Belt Structure

  • Origin of Radiation Belt

  • Radiation Belt Slot region

  • Safe-zone Solar-Cycle Shifting.


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


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