Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Cluster satellite observations of mHz pulsations in the dayside magnetosphere
KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
Institute for Geophysics and Extraterrestrial Physics, Technical University of Braunschweig, Tyskland.
2006 (English)In: Advances in Space Research, ISSN 0273-1177, Vol. 38, no 8, 1730-1737 p.Article in journal (Refereed) Published
Abstract [en]

On 17 August 2002 the Cluster spacecraft moved through the dayside magnetosphere. Between 16:00 and 18:30 LIT clear monochromatic oscillations are seen in both electric field and magnetometer data. The frequency is 4.2 mHz in the spacecraft frame of reference. The oscillations have a clear spatial localisation. The magnetic field oscillations are radially polarised in the plane perpendicular to the background magnetic field, indicating that the wave is in the poloidal mode. From the difference in phase between the satellites we estimate the azimuthal wave number, in, to be about 130, consistent with the magnetic field polarisation. The frequency is stable for different L-values as well as over time. From the value of in, the Doppler shift due to satellite motion is estimated to 0.5 mHz. By looking at the phase of the electric and the magnetic field close to the equator we conclude that the oscillations are in a mode with an odd number of half wavelengths between the two ionospheres.

Place, publisher, year, edition, pages
2006. Vol. 38, no 8, 1730-1737 p.
Keyword [en]
ULF pulsations
National Category
Fusion, Plasma and Space Physics
Identifiers
URN: urn:nbn:se:kth:diva-5813DOI: 10.1016/j.asr.2005.04.103ISI: 000202988500024Scopus ID: 2-s2.0-33845991191OAI: oai:DiVA.org:kth-5813DiVA: diva2:10319
Note

QC 20100707. Konferens: 35th COSPAR Scientific Assembly Paris, FRANCE, JUL 18-25, 2004 Comm Space Res.

Available from: 2005-08-25 Created: 2005-08-25 Last updated: 2012-09-17Bibliographically approved
In thesis
1. Resonant Waves in the Terrestrial Magnetosphere
Open this publication in new window or tab >>Resonant Waves in the Terrestrial Magnetosphere
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Waves in the mHz frequency range are a prominent feature in the terrestrial magnetosphere. In this frequency range the waves have wavelengths comparable to the lengths of the geomagnetic field lines. The waves are then standing waves along closed field lines with endpoints in the southern and northern ionosphere. Waves play an important role in the distribution of energy in the magnetosphere and mHz waves can accelerate electrons to MeV energies and have been proposed as a driver of auroral arcs. They can also be used as a diagnostic tool for determining the plasma density. There are two important classes of these low frequency waves. One has large azimuthal wavelength and is usually associated with driving mechanisms outside the magnetosphere, such as the Kelvin-Helmholtz instability at the magnetopause. The other has small azimuthal wavelength and is associated with plasma instabilities inside the magnetosphere. Both types of waves are studied in this thesis with an emphasis on the small azimuthal wavelength waves. For the type of wave with large azimuthal wavelength there is however, a considerable debate about the driving mechanism. One recently suggested driver is coherent magnetohydrodynamic waves in the solar wind. Part of this thesis studies this experimentally and we conclude that, at least on some occasions, this driving mechanism come into play. The Cluster satellites are used to study the morphology of the waves. We demonstrate the ability of Cluster to determine the azimuthal wave number of the waves and also how the structure along the magnetic field lines can be determined. This gives information regarding the harmonic number of the standing waves, which in turn says something about the driver of the waves. We also look at possible excitation mechanisms for the small azimuthal wavelength waves.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. xi, 45 p.
Series
Trita-ALP, ISSN 1103-6613 ; 2005:05
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-400 (URN)91-7178-105-6 (ISBN)
Presentation
2005-09-12, Seminarierummet, Teknikringen 31, Stockholm, 13:00
Opponent
Supervisors
Note
QC 20101129Available from: 2005-08-25 Created: 2005-08-25 Last updated: 2010-11-29Bibliographically approved
2. Multi-point Measurements of Ultra Low Frequency Waves in the Terrestrial Magnetosphere
Open this publication in new window or tab >>Multi-point Measurements of Ultra Low Frequency Waves in the Terrestrial Magnetosphere
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Waves in the mHz frequency range are prominent features of the terrestrial magnetosphere. In this frequency range the waves have wavelengths comparable to the lengths of the geomagnetic field lines. The waves are then standing waves along closed field lines with endpoints in the southern and northern ionosphere. Waves play an important role in the distribution of energy in the magnetosphere and mHz waves can accelerate electrons to MeV energies and have been proposed as driving mechanism for auroral arcs. They can also be used as diagnostic tools for determining the plasma density. There are two important classes of these low frequency waves. One has large azimuthal wavelength and is usually associated with driving mechanisms outside the magnetosphere, such as the Kelvin-Helmholtz instability at the magnetopause. The other has small azimuthal wavelength and is associated with plasma instabilities inside the magnetosphere. Both types of waves are studied in this thesis with a slight emphasis on the large azimuthal wavelength waves. For the type of wave with large azimuthal wavelength there is however, a considerable debate about the driving mechanism. One recently suggested driver is coherent magnetohydrodynamic waves in the solar wind. Part of this thesis studies this experimentally and we conclude that, at least on some occasions, this driving mechanism comes into play. The Cluster satellites are used to study the morphology of the waves. We demonstrate the ability of Cluster to determine the azimuthal wave number of the waves and also how the structure along the magnetic field lines can be determined. This gives information regarding the harmonic number of the standing waves, which in turn says something about the driver of the waves. We also look at possible excitation mechanisms for the small azimuthal wavelength waves.

Place, publisher, year, edition, pages
Stockholm: KTH, 2007. xi, 52 p.
Series
Trita-EE, ISSN 1653-5146 ; 2007:014
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-4404 (URN)978-91-7178-615-9 (ISBN)
Public defence
2007-06-08, Sal F3, KTH, Lindstedtsvägen 26, Stockhol, 10:00
Opponent
Supervisors
Note
QC 20100707Available from: 2007-05-29 Created: 2007-05-29 Last updated: 2010-07-07Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Eriksson, TommyBlomberg, Lars
By organisation
Space and Plasma Physics
In the same journal
Advances in Space Research
Fusion, Plasma and Space Physics

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 73 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf