Observation of low frequency electromagnetic activity at 1000 km altitude
- Alfvén Laboratory, Royal Institute of Technology, Stockholm, Sweden
Abstract. We present a statistical study of low frequency fluctuations of electric and magnetic fields, commonly interpreted as Alfvénic activity. The data base consists of six months of electric and magnetic field measurements by the Astrid-2 microsatellite. The occurrence of the events is studied with respect to the location and general activity. Large regions of broadband Alfvénic activity are persistently observed in the cusp/cleft and, during the periods of high geo-magnetic activity, also in the pre-midnight sector of the auroral oval.
Key words. Ionosphere (auroral ionosphere) – Space plasma physics (waves and instabilities) – Magnetospheric physics (magnetosphere-ionosphere interactions)