Prebreakup arcs: A comparison between theory and experiment

Journal Article · Thu Aug 01 00:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/91JA01268· OSTI ID:5152841

Rothwell, P L ^[1]; Silevitch, M B ^[2]; Block, L P; Faelthammar, C G ^[3]

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1. Phillips Lab., Hanscom AFB, MA (United States)
2. Northeastern Univ., Boston, MA (United States)
3. Royal Inst. of Tech., Stockholm (Sweden)

The authors have developed a model describing the structure of a prebreakup arc based on an ionospheric Cowling channel and its extension into the magnetosphere. A coupled two-circuit representation of the substorm current wedge is used which is locally superimposed on both westward and eastward electrojets. They find that brighter, more unstable prebreakup arcs are formed in the premidnight than in the postmidnight sector. This contributes to the observed prevalence of auroral activity in the premidnight sector. Also, the model predicts that the north-south dimensions of the current wedge in the ionospheree should vary from a few kilometers at an invarient latitude ({Lambda}) of 62{degree} to hundreds of kilometers above {Lambda} = 68{degree}. Comparison of the model results with the extensive observations of Marklund et al (1983) for a specific arc observed just after onset shows good agreement, particularly for the magnitude of the polarization electric field and the arc size. They conclude that this agreement is further evidence that the substorm breakup arises from magnetosphere-ionosphere coupling in the near magnetosphere and that the steady state model developed here is descriptive of the breakup arc before inductive effects become dominant.

• OSTI ID: 5152841
• Journal Information: Journal of Geophysical Research; (United States), Vol. 96:A8; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
MAGNETIC BAYS
MATHEMATICAL MODELS
AURORAE
COMPARATIVE EVALUATIONS
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
ELECTRIC FIELDS
ELECTROJETS
EXPANSION
IONOSPHERE
CURRENTS
EARTH ATMOSPHERE
EVALUATION
PLANETARY IONOSPHERES
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena