11.1 Magnetic Dipole Field

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11.1 Magnetic Dipole Field
2
11.1 Magnetic Dipole Field (2)
I
B
3
11.1 Magnetic Dipole Field (3)
r
Br
B
dr
r
rdq
Bq
q
4
11.2 Geomagnetic Field
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11.2 Geomagnetic Field (2)
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11.3 Geomagnetic variations
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11.3 Geomagnetic variations (1)

• The geomagnetic field shows significant
  variability during quiet times and magnetically
  disturbed periods.
• Quiet time variability results from tidal waves
  caused by solar heating and lunar gravitational
  forces. Tidal motion moves ions across field
  lines generating dynamo electric fields.
• Solar-quiet current system Sq currents
• Lunar current system L currents

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11.3 Geomagnetic variations (2)

• Disturbance field D?B-BSq-BL
• D?Dst-Ds
• Dst is the storm-time variation caused by the
  ring current disturbances
• Ds is the disturbance caused by auroral particle
  precipitation
• Kp index
• Local K index 12 stations (in the northern
  mid-latitudes) measure the average magnetic
  variation for every 3 hours with log scale
• 00, 0, 1-, 10, 1, 2-, 9-, 90, 9
• Planetary Kp index average of the 12 stations

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11.4 Ionospheric Layers
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11.4 Ionospheric Layers (2)
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11.4 Ionospheric Layers (3)
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11.4 Ionospheric Layers (4)
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11.4 Dominant Processes in the Ionosphere

• E and F1 region photochemistry is dominant
• F2 region photochemistry and diffusion
• Topside F2 region diffusion is dominant
• Plasma motion along B
• Ambipolar diffusive forces are vertical Fag,
  dT/dz, dn/dz
• FaFasinI
• uazuasinI
• See Fig.11.7 for effects
• of neutral wind and E.

I
Fa
Fa
I
ua
uaz
B
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11.4 Ionospheric Layers (5)