EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Farrugia et al. 1994
Farrugia, C.J., Sandholt, P.E. and Burlaga, L.F. (1994). Auroral activity associated with Kelvin-Helmholtz instability at the inner edge of the low-latitude boundary layer. Journal of Geophysical Research 99: doi: 10.1029/94JA00926. issn: 0148-0227.

Auroral activity occurred in the late afternoon sector (~16 MLT) in the northern hemisphere during the passage at Earth of an interplanetary magnetic cloud on January 14, 1988. The auroral activity consisted of a very dynamic display which was preceded and followed by quiet auroral displays. During the quiet displays, discrete rayed arcs aligned along the geomagnetic L shells were observed. In the active stage, rapidly evolving spiral forms centered on magnetic zenith were evident. The activity persisted for many minutes and was characterized by the absence of directed motion. They were strongly suggestive of intense filaments of upward field-aligned currents embedded in the large-scale region 1 current system. Distortions of the flux ropes as they connect from the equatorial magnetosphere to the ionosphere were witnessed. We assess as possible generating mechanisms three nonlocal sources known to be associated with field-aligned currents. Of these, partial compressions of the magnetosphere due to variations of solar wind dynamic pressure seem an unlikely source. The possibility that the auroral forms are due to reconnection is investigated but is excluded because the active aurora were observed on the closed field line region just equatorward of the convection reversal boundary. To support this conclusion further, we apply recent results on the mapping of ionospheric regions to the equatorial plane based on the Tsyganenko 1989 model (Kaufmann et al., 1993).

We find that for comparable magnetic activity the aurora map to the equatorial plane at XGSM=~3 RE and ~2 RE inward of the magnetopause, that is, the inner edge of the boundary layer close to dusk. Since the auroraol forms are manifestly associated with magnetic field shear, a vortical motion at the equatorial end of the flux rope is indicated, making the Kelvin-Helmholtz instability acting at the inner edge of the low-latitude boundary layer the most probable generating source. Our proposed auroral signature of viscous-type solar wind-magnetosphere interaction is easily distinguished from the well-documented sequence of moving auroral forms in the near-noon sector, which are observed to be associated with a time-dependent structure of merging-cell convection. ¿ American Geophysical Union 1994

BACKGROUND DATA FILES

Abstract

Keywords
Interplanetary Physics, Interplanetary magnetic fields, Magnetospheric Physics, Auroral phenomena, Magnetospheric Physics, Plasma convection, Space Plasma Physics, Magnetic reconnection
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit