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| Titel |
Reconstruction of two-dimensional magnetopause structures from Cluster observations: verification of method |
| VerfasserIn |
H. Hasegawa, B. U. Ö. Sonnerup, M. W. Dunlop, A. Balogh, S. E. Haaland, B. Klecker, G. Paschmann, B. Lavraud, I. Dandouras, H. Rème |
| 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.1251-1266 |
| Datensatznummer |
250014837
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| Publikation (Nr.) |
 copernicus.org/angeo-22-1251-2004.pdf |
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| Zusammenfassung |
| A recently developed technique for reconstructing approximately
two-dimensional (∂/∂z≈0), time-stationary
magnetic field structures in space is applied to two magnetopause traversals
on the dawnside flank by the four Cluster spacecraft, when the spacecraft
separation was about 2000km. The method consists of solving the
Grad-Shafranov equation for magnetohydrostatic structures, using plasma and
magnetic field data measured along a single spacecraft trajectory as spatial
initial values. We assess the usefulness of this single-spacecraft-based
technique by comparing the magnetic field maps produced from one spacecraft
with the field vectors that other spacecraft actually observed. For an
optimally selected invariant (z)-axis, the correlation between the field
components predicted from the reconstructed map and the corresponding
measured components reaches more than 0.97. This result indicates that the
reconstruction technique predicts conditions at the other spacecraft
locations quite well.
The optimal invariant axis is relatively close to the
intermediate variance direction, computed from minimum variance analysis of
the measured magnetic field, and is generally well determined with respect to
rotations about the maximum variance direction but less well with respect to
rotations about the minimum variance direction. In one of the events, field
maps recovered individually for two of the spacecraft, which crossed the
magnetopause with an interval of a few tens of seconds, show substantial
differences in configuration. By comparing these field maps, time evolution
of the magnetopause structures, such as the formation of magnetic islands, motion
of the structures, and thickening of the magnetopause current layer, is
discussed.
Key words. Magnetospheric physics (Magnetopause, cusp,
and boundary layers) – Space plasma physics (Experimental
and mathematical techniques, Magnetic reconnection) |
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