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| Titel |
MHD model of magnetosheath flow: comparison with AMPTE/IRM observations on 24 October, 1985 |
| VerfasserIn |
C. J. Farrugia, H. K. Biernat, N. V. Erkaev, L. M. Kistler, G. Le, T. Russell |
| 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 ; 16, no. 5 ; Nr. 16, no. 5, S.518-527 |
| Datensatznummer |
250013272
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| Publikation (Nr.) |
 copernicus.org/angeo-16-518-1998.pdf |
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| Zusammenfassung |
We compare numerical results obtained from a
steady-state MHD model of solar wind flow past the terrestrial magnetosphere
with documented observations made by the AMPTE/IRM spacecraft on 24 October,
1985, during an inbound crossing of the magnetosheath. Observations indicate
that steady conditions prevailed during this about 4 hour-long crossing. The
magnetic shear at spacecraft entry into the magnetosphere was 15°. A
steady density decrease and a concomitant magnetic field pile-up were observed
during the 40 min interval just preceding the magnetopause crossing. In this
plasma depletion layer (1) the plasma beta dropped to values below unity; (2)
the flow speed tangential to the magnetopause was enhanced; and (3) the local
magnetic field and velocity vectors became increasingly more orthogonal to each
other as the magnetopause was approached (Phan et al., 1994). We model
parameter variations along a spacecraft orbit approximating that of AMPTE/IRM,
which was at slightly southern GSE latitudes and about 1.5 h post-noon Local
Time. We model the magnetopause as a tangential discontinuity, as suggested by
the observations, and take as input solar wind parameters those measured by
AMPTE/IRM just prior to its bow shock crossing. We find that computed field and
plasma profiles across the magnetosheath and plasma depletion layer match all
observations closely. Theoretical predictions on stagnation line flow near this
low-shear magnetopause are confirmed by the experimental findings. Our theory
does not give, and the data on this pass do not show, any localized density
enhancements in the inner magnetosheath region just outside the plasma depletion
layer.
Key words. Steady-state magnetosheath · Plasma
depletion layer · Stagnation line flow |
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