Magnetic

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Magnetic Acoustic Waves in the Aurora
Jada Maxwell
Photo Michael KlenschCourtesy of
httpwww.nordlys.com
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Can magnetic waves in the aurora transform into
acoustic waves?
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Magnetic Waves
Earth
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Transform into Sound Waves
Earth
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Types of Magnetic Waves

• Alfvén waves (s-mode)

• Magnetosonic (like acoustic wavesp-mode)

Images courtesy of Georgia State
Universityhttp//hyperphysics.phy-astr.gsu.edu/hb
ase/sound/tralon.html
BBC animations
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Velocity of Waves
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Beta
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Plasma is like Rubber Bands in Jello
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Where Does Beta1?
Location Altitude (km)
Fairbanks, Ak 120
Seattle, Wa 120
Equator 150
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Earths Atmosphere
Image courtesy of http//en.wikipedia.org/wiki/Ima
geAtmosphere_model.pngGraph made from data
obtained at http//uap-www.nrl.navy.mil/models_web
/msis/msis_home.htm
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Calculating Magnetic Pressure (PB)
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Calculating Gas Pressure (PG)
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Calculating Velocity of Acoustic Waves (CS)
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Calculating Velocity of Alfvén Wave (VA)
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Calculations for Fairbanks, Ak
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Where Does Beta1?
Location Altitude (km)
Fairbanks, Ak 120
Seattle, Wa 120
Equator 150
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More Questions to Investigate

• How does atmospheric heating from auroral
  processes affect Beta?
• At what frequencies do these waves occur?
• How much does wave transformation contribute to
  infrasound compared with the gas expansion theory?

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Sources

• Thanks to Dr. E.J. Zita for her guidance and
  helpful discussions
• Johnson, M.C., Petty-Powell, Sarah and Zita,
  E.J., Energy Transport by MHD Waves Above the
  Photosphere Numerical Simulations, 17 Oct 2002
• Michael KlenschCourtesy of httpwww.nordlys.com
• http//en.wikipedia.org/wiki/ImageAtmosphere_mode
  l.pngGraph made from data obtained at
  http//uap-www.nrl.navy.mil/models_web/msis/msis_h
  ome.htm
• Georgia State Universityhttp//hyperphysics.phy-a
  str.gsu.edu/hbase/sound/tralon.html

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http//academic.evergreen.edu/m/maxjad02