Ground-based and satellite observations of high-latitude auroral activity in the dusk sector of the auroral oval

K. Kauristie (1) , T. I. Pulkkinen (1) , O. Amm (1) , A. Viljanen (1) , M. Syrjäsuo (1) , P. Janhunen (1) , S. Massetti (2) , S. Orsini (2) , M. Candidi (2) , J. Watermann (3) , E. Donovan (4) , P. Prikryl (5) , I. R. Mann (6) , P. Eglitis (7) , C. Smith (8) , W. F. Denig (9) , H. J. Opgenoorth (1, 7) , M. Lockwood (10) , M. Dunlop (11) , A. Vaivads (7) , M. André (7)

1 Geophysical Research Division [Helsinki]
2 CNR - National Research Council of Italy | Consiglio Nazionale delle Ricerche
3 DMI - Danish Meteorological Institute
4 University of Calgary
5 CRC - Communications Research Centre Canada
6 University of York [York, UK]
7 IRF - Swedish Institute of Space Physics [Kiruna]
8 Bartol Research Institute
9 AFRL - Air Force Research Laboratory
10 RAL - STFC Rutherford Appleton Laboratory
11 Imperial College London

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 B_Z. 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 B_Z 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.

Domaines: Océan, Atmosphère; Sciences de la Terre

K. Kauristie, T. I. Pulkkinen, O. Amm, A. Viljanen, M. Syrjäsuo, et al.. Ground-based and satellite observations of high-latitude auroral activity in the dusk sector of the auroral oval. Annales Geophysicae, 2001, 19 (10/12), pp.1683-1696. ⟨hal-00316959⟩