Conjugate observations of quasi-periodic emissions by Cluster and DEMETER spacecraft

F. Němec; O. Santolík; Michel Parrot; J. S. Pickett; M. Hayosh; Nicole Cornilleau-Wehrlin

doi:10.1029/2012JA018380

Conjugate observations of quasi-periodic emissions by Cluster and DEMETER spacecraft

F. Němec ¹ O. Santolík ¹ Michel Parrot ² J. S. Pickett ³ M. Hayosh ⁴ Nicole Cornilleau-Wehrlin ^{5, 6}

1 Faculty of Mathematics and Physics [Praha/Prague]

2 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace

3 Department of Physics and Astronomy, University of Iowa

4 IAP - Institute of Atmospheric Physics [Prague]

5 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique

6 LPP - Laboratoire de Physique des Plasmas

Abstract : Quasi-periodic (QP) emissions are electromagnetic emissions at frequencies of about 0.5-4 kHz that are characterized by a periodic time modulation of the wave intensity. Typical periods of this modulation are on the order of minutes. We present a case study of a large-scale long-lasting QP event observed simultaneously on board the DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) and the Cluster spacecraft. The measurements by the Wide-Band Data instrument on board the Cluster spacecraft enabled us to obtain high-resolution frequency-time spectrograms of the event close to the equatorial region over a large range of radial distances, while the measurements by the STAFF-SA instrument allowed us to perform a detailed wave analysis. Conjugate observations by the DEMETER spacecraft have been used to estimate the spatial and temporal extent of the emissions. The analyzed QP event lasted as long as 5 h and it spanned over the L-shells from about 1.5 to 5.5. Simultaneous observations of the same event by DEMETER and Cluster show that the same QP modulation of the wave intensity is observed at the same time at very different locations in the inner magnetosphere. ULF magnetic field fluctuations with a period roughly comparable to, but somewhat larger than the period of the QP modulation were detected by the fluxgate magnetometers instrument on board the Cluster spacecraft near the equatorial region, suggesting these are likely to be related to the QP generation. Results of a detailed wave analysis show that the QP emissions detected by Cluster propagate unducted, with oblique wave normal angles at higher geomagnetic latitudes.

Keywords : magnetospheric electromagnetic wave propagation

Type de document :

Article dans une revue

Journal of Geophysical Research : Space Physics, American Geophysical Union/Wiley, 2013, 118 (1), pp.198-208. 〈10.1029/2012JA018380〉

Domaine :

Planète et Univers [physics]

Liste complète des métadonnées

Littérature citée [40 références] Voir Masquer Télécharger

https://hal-insu.archives-ouvertes.fr/insu-01289740
Contributeur : Nathalie Rouchon <>
Soumis le : vendredi 20 mai 2016 - 14:36:49
Dernière modification le : jeudi 7 février 2019 - 15:49:52

jgra50023.pdf

Fichiers éditeurs autorisés sur une archive ouverte

Conjugate observations of quasi-periodic emissions by Cluster and DEMETER spacecraft

Fichier

Identifiants

Collections

Citation

Exporter

Métriques

247

76

Contact

Conjugate observations of quasi-periodic emissions by Cluster and DEMETER spacecraft

Fichier

Identifiants

Collections

Citation

Exporter

Partager

Métriques

247

76

Contact