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Ann. Geophys., 19, 1683-1696, 2001
www.ann-geophys.net/19/1683/2001/
© European Geosciences Union 2001
Ground-based and satellite observations of high-latitude auroral activity in the dusk sector of the auroral oval
K. Kauristie1, T. I. Pulkkinen1, O. Amm1, A. Viljanen1, M. Syrjäsuo1, P. Janhunen1, S. Massetti2, S. Orsini2, M. Candidi2, J. Watermann3, E. Donovan4, P. Prikryl5, I. R. Mann6, P. Eglitis7, C. Smith8, W. F. Denig9, H. J. Opgenoorth1,7, M. Lockwood10, M. Dunlop11, A. Vaivads7, and M. André7
1Finnish Meteorological Institute, Geophysical Research Division, P.O.Box 503, FIN-00101 Helsinki, Finland
2Consiglio Nazionale delle Ricerche, Istituto di Fisica dello Spazio Interplanetario, Rome, Italy
3Danish Meteorological Institute, Solar-Terrestrial Physics Division, Copenhagen, Denmark
4University of Calgary, Department of Physics and Astronomy, Alberta, Canada
5Communications Research Centre, Ottawa, Canada
6University of York, Department of Physics, UK
7Swedish Institute of Space Physics, Uppsala Division, Sweden
8Bartol Research Institute, Delaware, USA
9Air Force Research Laboratory, Hanscom Air Force Base, Massachusetts, USA
10Rutherford Appleton Laboratory, Didcot, UK
11Imperial College, London, UK
Abstract. On 7 December 2000,
during 13:30–15:30 UT the MIRACLE all-sky camera at Ny Ålesund observed
auroras at high-latitudes (MLAT ~ 76) simultaneously when the Cluster
spacecraft were skimming the magnetopause in the same MLT sector (at ~ 16:00–18:00
MLT). The location of the auroras (near the ionospheric convection reversal
boundary) and the clear correlation between their dynamics and IMF variations
suggests their close relationship with R1 currents. Consequently, we can assume
that the Cluster spacecraft were making observations in the magnetospheric
region associated with the auroras, although exact magnetic conjugacy between
the ground-based and satellite observations did not exist. The solar wind
variations appeared to control both the behaviour of the auroras and the
magnetopause dynamics. Auroral structures were observed at Ny Ålesund
especially during periods of negative IMF BZ. In addition,
the Cluster spacecraft experienced periodic (T ~ 4 - 6 min) encounters
between magnetospheric and magnetosheath plasmas. These undulations of the
boundary can be interpreted as a consequence of tailward propagating
magnetopause surface waves. Simultaneous dusk sector ground-based observations
show weak, but discernible magnetic pulsations (Pc 5) and occasionally periodic
variations (T ~ 2 - 3 min) in the high-latitude auroras. In the dusk
sector, Pc 5 activity was stronger and had characteristics that were consistent
with a field line resonance type of activity. When IMF BZ
stayed positive for a longer period, the auroras were dimmer and the spacecraft
stayed at the outer edge of the magnetopause where they observed
electromagnetic pulsations with T ~ 1 min. We find these observations
interesting especially from the viewpoint of previously presented studies
relating poleward-moving high-latitude auroras with pulsation activity and MHD
waves propagating at the magnetospheric boundary layers.
Key words. Ionosphere
(ionosphere-magnetosphere interaction) – Magnetospheric physics (auroral
phenomena; solar wind – magnetosphere interactions)
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