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Excitation of tall auroral rays by ohmic heating in field-aligned current filaments at F region heights

Excitation of tall auroral rays by ohmic heating in field-aligned current filaments at F region heights
Excitation of tall auroral rays by ohmic heating in field-aligned current filaments at F region heights
The formation of tall red rays in the ionosphere has been a longstanding unresolved problem of auroral physics. These rays are pencil-like structures which can extend from 150 km at their base to as high as 600 km. At these heights it is very difficult to deposit sufficient power in order to account for the luminosity of tall rays. This work examines ohmic heating by collisional processes in strong field-aligned current sheets to account for visible tall rays. The mechanism is demonstrated by two-dimensional simulation in a fully self-consistent treatment of the ionosphere and coupling to the magnetosphere. We find that a filamentary current density of about 600 µAm-2 over about ten seconds can pump sufficient energy into the ambient oxygen atoms to produce visible auroral red rays. The ohmic heating leads to an electron temperature in excess of 10,000 K in the upper F-region.
0148-0227
8017
Otto, A.
7a7273f8-b54e-438f-a3b4-ed59323cdacc
Lummerzheim, D.
6432baa4-48ac-4203-bc2d-973de7f3efde
Zhu, H.
56de08ce-886f-4d04-bbc5-ee175ce014ae
Lie-Svendsen, Ø.
ca9ba3f7-c4c7-469a-b3ea-b2d27e721fe6
Rees, M.H.
6ecc0166-51bf-4afd-9471-acbb415fd156
Lanchester, B.S.
e864533e-eea0-471f-a3f9-7c70c25be55b
Otto, A.
7a7273f8-b54e-438f-a3b4-ed59323cdacc
Lummerzheim, D.
6432baa4-48ac-4203-bc2d-973de7f3efde
Zhu, H.
56de08ce-886f-4d04-bbc5-ee175ce014ae
Lie-Svendsen, Ø.
ca9ba3f7-c4c7-469a-b3ea-b2d27e721fe6
Rees, M.H.
6ecc0166-51bf-4afd-9471-acbb415fd156
Lanchester, B.S.
e864533e-eea0-471f-a3f9-7c70c25be55b

Otto, A., Lummerzheim, D., Zhu, H., Lie-Svendsen, Ø., Rees, M.H. and Lanchester, B.S. (2003) Excitation of tall auroral rays by ohmic heating in field-aligned current filaments at F region heights. Journal of Geophysical Research, 108 (A4), 8017. (doi:10.1029/2002JA009423).

Record type: Article

Abstract

The formation of tall red rays in the ionosphere has been a longstanding unresolved problem of auroral physics. These rays are pencil-like structures which can extend from 150 km at their base to as high as 600 km. At these heights it is very difficult to deposit sufficient power in order to account for the luminosity of tall rays. This work examines ohmic heating by collisional processes in strong field-aligned current sheets to account for visible tall rays. The mechanism is demonstrated by two-dimensional simulation in a fully self-consistent treatment of the ionosphere and coupling to the magnetosphere. We find that a filamentary current density of about 600 µAm-2 over about ten seconds can pump sufficient energy into the ambient oxygen atoms to produce visible auroral red rays. The ohmic heating leads to an electron temperature in excess of 10,000 K in the upper F-region.

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Published date: 2003

Identifiers

Local EPrints ID: 9137
URI: http://eprints.soton.ac.uk/id/eprint/9137
ISSN: 0148-0227
PURE UUID: 56fc926d-b633-4a79-99b5-fd3c0b7494ff

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Date deposited: 24 Sep 2004
Last modified: 15 Mar 2024 04:55

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Contributors

Author: A. Otto
Author: D. Lummerzheim
Author: H. Zhu
Author: Ø. Lie-Svendsen
Author: M.H. Rees
Author: B.S. Lanchester

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