Stable auroral red arcs
Sar-arcs are diffuse, persistent, practically monochromatic ( lambda lambda 6300 to 64A) auroral forms peculiar to mid-latitude regions of Earth. Measurements of such parameters as spectral composition, geomagnetic location, range of intensity, and frequency of occurrence lead to the conclusion that the phenomenon is due to the excitation of atomic oxygen by hot electrons in the plasmapause region. However, on the basis of the the data available, it is not clear whether fresh electrons are precipitating into the region of the arc or whether ambient electrons are being heated in place. There is strong evidence that the source of energy in either case is the ring current. Suggested mechanisms by which energy is transferred from the ring current to the electrons in the SAR-arc region are: 1) heat flow, that is, transfer of kinetic energy to the SAR-arc region by Coulomb collisions, 2) transfer of ring current proton kinetic energy to hydromagnetic waves which are in turn damped by the electrons in the SAR-arc region, 3) direct influx of energetic electrons into the SAR-arc region. Which of these mechanisms predominates is still not resolved at this time. There are other open questions as well including ones dealing with the motion of the arcs and the spectral composition. (auth)
- Research Organization:
- Battelle Pacific Northwest Labs., Richland, Wash. (USA)
- DOE Contract Number:
- AT(45-1)-1830
- NSA Number:
- NSA-29-005961
- OSTI ID:
- 4399941
- Report Number(s):
- BNWL-SA-4788; CONF-730962-1
- Resource Relation:
- Conference: 2. IAGA general assembly, International Association of Geomagnetism and Aeronomy, Kyoto, Japan, 13 Sep 1973; Other Information: Orig. Receipt Date: 30-JUN-74
- Country of Publication:
- United States
- Language:
- English
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