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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

Space Plasma Physics

Earth’s Radiation Belt

Xi Shao

Department of Astronomy,

University Of Maryland, College Park, MD 20742


Outline

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.


Earth s radiation belt

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.


Earth s radiation 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)


Earth s radiation belt

The Radiation Belts Today:

a Dynamic Space Weather Environment


Why trapped
Why Trapped?

Proton Orbit

Electron Orbit


Earth s radiation belt

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



Earth s radiation belt

Electron (> 300 keV) Belt Dynamics

(1979-1991)

Outer Belt

Weakens

Mar. 1991

Mar. 1989

Feb. 1986

Jul. 1982

Apr. 1981

Inner belt

Enhanced


Earth s radiation belt

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.



Earth s radiation belt

Proton (> 80 MeV) Belt Dynamics

(1979-1991)

Mar. 1991

Mar. 1989

Feb. 1986


Earth s radiation belt

Proton (> 80 MeV) Belt Dynamics

(1992-2004)

Oct-Nov, 2003



Earth s radiation belt

Space Plasma Physics Origin.

Modeling Solar Wind Interaction with Earth’s Magnetosphere

MHD Equations Solved on a 3D Stretched Spherical Mesh


Magnetospheric storms substorms

Space Plasma Physics Origin.

Magnetospheric Storms/Substorms




Earth s radiation belt

Space Plasma Physics Origin.

  • Magnetospheric Substorm


Earth s radiation belt

Mid-Tail Reconnection Origin.

t= 00:-07:-48

t= 00:47:20

t= 00:51:05

t= 00:56:06

t= 01:01:07

t= 01:06:08



Earth s radiation belt

Space Plasma Physics Origin.

Ring Current Development

1:00 UT


Earth s radiation belt

Space Plasma Physics Origin.

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




Earth s radiation belt

Energization of Radiation Belt Electrons Origin.

Initial Configuration of 5keV electrons

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


Formation of slot region in electron radiation belt
Formation of Slot Region in Electron Radiation Belt Origin.

Whistler Waves in the

Plasmasphere

Slot Region




Summary
Summary Origin.

  • 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
Outstanding science questions Origin.

  • 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