Abstract During the onset of magnetospheric substorms in the night sector, impulsive fluctuations are observed in the ULF range at geostationary orbit. A detailed analysis of the electric and magnetic components, simultaneously detected on board the ESA GEOS-2 spacecraft, permits identification of three different waves: (i) Quasi Electrostatic waves (QES) and (ii) magnetosonic waves, both of which exhibit a predominant component parallel to the DC magnetic field at frequencies above the proton gyrofrequency fH + and (iii) transverse shear Alfvén waves propagating azimuthally at frequencies below fH +. Comparison with particle measurements (ions and electrons) in different energy ranges shows that QES waves are related to electron precipitation leading to auroras at the footprint of the GEOS field line, whereas the magnetosonic waves are observed in the ring current where energetic ion and electron fluxes are large.
Characterization of small scale turbulence observed at substorm onsets: Relationships with parallel acceleration of particles
Advances in Space Research ; 13 , 4 ; 217-222
1993-01-01
6 pages
Article (Journal)
Electronic Resource
English
Multisatellite investigations of substorm onsets
Elsevier | 1985
|Inertial currents and substorm onsets
British Library Online Contents | 1996
|Substorm onsets observed by CRRES: constraints on energetic electron source regions
British Library Online Contents | 1996
|The Role of Waves in Substorm Onsets
NTRS | 1998
|Substorm-associated ion acceleration in the dynamic magnetotail
British Library Online Contents | 1996
|