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Aurora

Stan SolomonHigh Altitude Observatory

National Center for Atmospheric Research

Summer Colloquium on Space Weather • NCAR Advanced Studies Program • 7 June 2005

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Is the Aurora Borealis similar to the Aurora Australis?

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Reconnection in the Magnetotail

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Coupled Magnetosphere-Ionosphere-Thermosphere Model

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Energetic Particles from the Magnetosphere

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Motion of Charged Particles Along a Magnetic Field Line

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Transport of Auroral Electrons in the Upper Atmosphere

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Penetration Depth of Auroral Electrons Depends on Energy

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Thermosphere and Ionosphere Composition

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Auroral Collisional Processes

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Electron Impact Ionization

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Ion Recombination Processes

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Simplified Schematic of Ion-Neutral Chemistry

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Examples of Auroral Emission Processes

e* + N2 2e* + N2+(B2u

+) N2+(B2u

+) N2+(X1g

+) + h (1N bands)

e* + N2 e* + N2(B3g) N2(B3g) N2(X1g+) + h (1P bands)

e* + N2 e* + N2(A3u+) N2 (A3u

+) N2(X1g+) + h (VK bands)

N2 (A3u+) + O(3P) N2(X1g

+) + O(1S)

O(1S) O(3P) + h (5577Å)

e* + O(3P) e* + O(1S) O(1S) O(3P) + h (5577Å) ~1s

e* + O(3P) e* + O(1D) O(1D) O(3P) + h (6300Å)

O2+ + e- O + O(1D) O(1D) O(3P) + h (6300Å) ~100s

O(1D) + N2 O(3P) + N2

e* + N2 e* + N(4S) + N(2D) N(2D) N(4S) + h (5200Å)

NO+ + e- O + N(2D) N(2D) N(4S) + h (5200Å) ~1e5s

N(2D) + O N(4S) + O

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Question for Discussion

Is this a good analogy?

The aurora has been compared to a cathode-ray tube (e.g., TV set, computer monitor, etc.)

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Photo Credits

Tom Eklund

Dave Fritts

NASA / Univ. Iowa

NASA / UC Berkeley

NASA STS

Stan Solomon