Electron temperature anisotropy associated to field-aligned currents in the Earth's magnetosphere inferred from Rosetta MIP-RPC observations during 2009 flyby

Abstract : A new approach is proposed for data interpretation of the Mutual Impedance Probe (MIP) instrument from the Rosetta Plasma Consortium (RPC) during the 2009 Earth's fly-by gravity assist through the magnetosphere, from dusk to dawn regions. The spacecraft trajectory of +/-8 Re (Earth's radius) was crossing several structures of field aligned currents (FACs) and radiations belts on both legs of the closest approach (CA, 2.450 km altitude). As routinely revealed by several pioneering space missions, natural and forced electrostatic wave emissions called Fq's were observed over +/- 3 Re at around CA using a dedicated mode of the MIP instrument. These emissions are lying between consecutive harmonics of the electron-cyclotron frequency, and their wavelength is perpendicular to the magnetic field-lines. Provided that the Fq's wavelengths projected along the MIP antenna might be estimated, it is shown that the local value of the Larmor radius can be deduced, hence the electron temperature component perpendicular to the magnetic field is subsequently derived. On the other hand, during the time of Fq's observations, the presence of VLF hiss emissions usually observed in these regions, gives us the possibility to determine the electron temperature anisotropy associated to the electrostatic electron anisotropy instability according to the theoretical model proposed by Gary and Cairns (JGR, vol.104,1999). Significant dynamic constraints revealed by crossing successive series of FACs tubes are shown being controlled by this anisotropy, and the fact that the magnetic pressure is significantly larger than the thermal pressure suggests that the FACs lobes are non-force free.
Type de document :
Article dans une revue
Journal of Geophysical Research : Space Physics, American Geophysical Union/Wiley, 2017, 122 (7), pp. 6964-6977 〈10.1002/2017JA024096〉
Liste complète des métadonnées

Littérature citée [45 références]  Voir  Masquer  Télécharger

https://hal-insu.archives-ouvertes.fr/insu-01544697
Contributeur : Catherine Cardon <>
Soumis le : jeudi 16 novembre 2017 - 10:17:58
Dernière modification le : mercredi 17 janvier 2018 - 17:04:06

Fichier

jgra53627.pdf
Fichiers éditeurs autorisés sur une archive ouverte

Identifiants

Citation

Christian Béghin, Michel Hamelin, Jean-Pierre Lebreton, Xavier Vallieres, Jérôme Moré, et al.. Electron temperature anisotropy associated to field-aligned currents in the Earth's magnetosphere inferred from Rosetta MIP-RPC observations during 2009 flyby. Journal of Geophysical Research : Space Physics, American Geophysical Union/Wiley, 2017, 122 (7), pp. 6964-6977 〈10.1002/2017JA024096〉. 〈insu-01544697〉

Partager

Métriques

Consultations de la notice

159

Téléchargements de fichiers

1