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| Titel |
Four-spacecraft determination of magnetopause orientation, motion and thickness: comparison with results from single-spacecraft methods |
| VerfasserIn |
S. E. Haaland, B. U. Ö. Sonnerup, M. W. Dunlop, A. Balogh, E. Georgescu, H. Hasegawa, B. Klecker, G. Paschmann, P. Puhl-Quinn, H. Rème, H. Vaith, A. Vaivads |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 22, no. 4 ; Nr. 22, no. 4 (2004-04-02), S.1347-1365 |
| Datensatznummer |
250014843
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| Publikation (Nr.) |
 copernicus.org/angeo-22-1347-2004.pdf |
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| Zusammenfassung |
In this paper, we use Cluster data
from one magnetopause event on 5 July 2001 to compare predictions from various
methods for determination of the velocity, orientation, and thickness of the
magnetopause current layer. We employ established as well as new
multi-spacecraft techniques, in which time differences between the crossings
by the four spacecraft, along with the duration of each crossing, are used to
calculate magnetopause speed, normal vector, and width. The timing is based on
data from either the Cluster Magnetic Field Experiment (FGM) or the Electric
Field Experiment (EFW) instruments.
The multi-spacecraft results are compared with those derived from
various single-spacecraft techniques, including minimum-variance analysis of
the magnetic field and deHoffmann-Teller, as well as Minimum-Faraday-Residue
analysis of plasma velocities and magnetic fields measured during the
crossings. In order to improve the overall consistency between multi-
and single-spacecraft results, we have also explored the use of hybrid
techniques, in which timing information from the four spacecraft is combined
with certain limited results from single-spacecraft methods, the remaining
results being left for consistency checks.
The results show good agreement between magnetopause orientations derived from
appropriately chosen single-spacecraft techniques and those obtained from
multi-spacecraft timing. The agreement between magnetopause speeds derived from
single- and multi-spacecraft methods is quantitatively somewhat less good but it is
evident that the speed can change substantially from one crossing to the next
within an event. The magnetopause thickness varied substantially from
one crossing to the next, within an event. It ranged from 5 to 10 ion gyroradii.
The density profile was sharper than the magnetic profile: most of the density
change occured in the earthward half of the magnetopause.
Key words. Magnetospheric physics (magnetopause, cusp
and boundary layers; instruments and techniques) – Space
plasma physics (discontinuities) |
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