SWARM Satellite and EISCAT Radar Observations of Auroral Arcs and Field-Aligned Currents
Tuesday, 24 May 2016: 8:45 AM
Anita Taina Aikio1, Heikki Vanhamäki1, Ilkka I Virtanen1, Björn Gustavsson2, Stephan C Buchert3, Kirsti Kauristie4, Claudia Stolle5 and David J Knudsen6, (1)University of Oulu, Oulu, Finland, (2)University of Tromsø, Tromsø, Norway, (3)Swedish Inst of Space Physics, Uppsala, Sweden, (4)Finnish Meteorological Inst, Helsinki, Finland, (5)Deutsches GeoForschungsZentrum GFZ, Potsdam, Germany, (6)University of Calgary, Calgary, AB, Canada
Abstract:
We study the SWARM satellite passes over night sector auroral arcs that are measured by the incoherent scatter EISCAT UHF and VHF radars in Tromso (67o cgmLat). The auroral arcs are observed optically by ground-based all-sky cameras. The electrodynamics of these arcs will be studied. Of special interest is one of the events during the Finnish EISCAT-SP experiment on 9 November 2015, when the auroral arc appears in the field-aligned UHF radar beam at the same time as the SWARM A and C fly over the Tromso magnetic field lines. The auroral differential electron energy flux is estimated from the radar-measured electron density altitude profiles. The spectral shape resembles inverted-V type. The field-aligned current carried by these down-coming electrons is calculated and it will be compared to the field-aligned current estimated from the data provided by the vector magnetic field instruments of SWARM. In addition, the tri-static VHF radar measurement yields the F-region electric field and it will be compared to the electric field provided by the EFI instrument of SWARM. The VHF radar shows high F-region ion temperatures located adjacent to the auroral arc, indicating large electric fields. While the EISCAT radars provide a local measurement of the electrodynamic parameters, the SWARM satellites yield measurements over a large latitudinal span of the night sector auroral oval.
