Formation and eruption of Sun-aligned arcs at the polar cap-auroral oval boundary
Journal Article
·
· Journal of Geophysical Research
- Utah State Univ., Logan, UT (United States)
- Cornell Univ., Ithaca, NY (United States)
- Boston Univ., Boston, MA (United States); and others
This paper reports on results from a study of the poleward edge of the auroral oval in the morning sector using a comprehensive blend of in situ and ground-based measurements. Three rockets, equipped to measure electric and magnetic fields, energetic particles, and plasma density flew into an auroral display whose dynamical features were recorded with a digital image intensified all-sky camera as well as with an incoherent scatter radar. In addition, a number of DMSP satellite measurements bracketed that launch time. Evidence is presented here that in a condition of declining magnetic activity Sun-aligned arcs are injected into the polar cap at velocities {approximately}7 km/s from locations of periodic brightening along the morningside of the auroral oval. The multipoint in situ measurements allow some separation of temporal and spatial effects and strongly suggest a poleward contraction of the convection pattern of about 0.25{degrees} INVL in 70 s. The most equatorward of the two brightest arcs studied erupted into a region which already was characterized by strong sunward convection. The most poleward, however, pushed into a region that had been convecting in an antisunward direction at velocities exceeding 1 km/s less than 2 min earlier, and it is likely that sunward convection subsequently pertained poleward of that arc as well. The authors believe that these events mark the reconfiguration of the magnetosphere into a system characterized by a smaller polar cap. 34 refs., 14 figs.
- OSTI ID:
- 166279
- Journal Information:
- Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A9 Vol. 99; ISSN JGREA2; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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