Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.490 IF 1.490
  • IF 5-year value: 1.445 IF 5-year
    1.445
  • CiteScore value: 2.9 CiteScore
    2.9
  • SNIP value: 0.789 SNIP 0.789
  • IPP value: 1.48 IPP 1.48
  • SJR value: 0.74 SJR 0.74
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 88 Scimago H
    index 88
  • h5-index value: 21 h5-index 21
Volume 21, issue 12
Ann. Geophys., 21, 2303–2314, 2003
https://doi.org/10.5194/angeo-21-2303-2003
© Author(s) 2003. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 21, 2303–2314, 2003
https://doi.org/10.5194/angeo-21-2303-2003
© Author(s) 2003. This work is distributed under
the Creative Commons Attribution 3.0 License.

  31 Dec 2003

31 Dec 2003

Pre-noon high-latitude auroral arcs as a manifestation of the interchange instability

A. E. Kozlovsky2,1, V. V. Safargaleev3, J. R. T. Jussila2, and A. V. Koustov4 A. E. Kozlovsky et al.
  • 1Sodankylä Geophysical Observatory, Sodankylä, FIN-99600, Finland
  • 2Department of Physical Sciences, University of Oulu, Oulu, FIN-90014, Finland
  • 3Polar Geophysical Institute, Apatity, 184200, Russia
  • 4Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada

Abstract. On 7 December 2000, TV ASC camera in Barentsburg (Svalbard) observed pre-noon (at 09:00–10:00 MLT) rayed auroral arcs, which occurred at the pole-ward edge of the auroral oval after an IMF transition from By -dominated (By = + 8.8, Bz = + 4.3) to strongly northward dominated (By = + 2.7, Bz = + 8.6). The arcs appeared from the area of enhanced luminosity seen in the western (nightside) horizon, and developed to the east, progressing at a velocity of about 1.5 km/s. Simultaneously, the arcs were drifting poleward at a velocity of 300–500 m/s, whose value was equal to the F-region ionospheric plasma drift velocity observed by the Incoherent Scatter Radar (ESR). The arc appearance and motion corresponded well to the poleward expansion of the auroral oval following the IMF shift, which was observed by the UVI on board the Polar satellite. The observed auroras were associated with closed LLBL indicated by the particle precipitation data from DMSP satellites showing also several-keV electrons of PS origin. The observations allow us to suggest that the arcs arise due to the interchange instability that starts to develop at the boundary between the magnetospheric plasma and the magnetosheath flux tubes entering the closed magnetosphere due to the reconnection beyond the cusp after the IMF changes. The interchange instability can be suggested as a possible mechanism for the formation of the LLBL. 

Key words. Magnetospheric physics (auroral phenomena; magnetopause, cusp and boundary layers; magnetospheric configuration and dynamics)

Publications Copernicus
Download
Citation