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| Titel |
Plasma depletion layer: Magnetosheath flow structure and forces |
| VerfasserIn |
Y. L. Wang, J. Raeder, C. 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 ; 22, no. 3 ; Nr. 22, no. 3 (2004-03-19), S.1001-1017 |
| Datensatznummer |
250014818
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| Publikation (Nr.) |
 copernicus.org/angeo-22-1001-2004.pdf |
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| Zusammenfassung |
The plasma depletion layer (PDL) is a layer on the sunward side of the magnetopause with
lower plasma density and higher magnetic field compared to the corresponding
upstream magnetosheath values.
In a previous study, we have validated the UCLA global (MHD) model in studying
the formation of the PDL by comparing model results, using spacecraft
solar wind observations as the driver, with in situ PDL observations.
In this study, we extend our previous work and examine
the detailed MHD forces responsible for the PDL formation.
We argue that MHD models, instead of gasdynamic models, should be
used to study the PDL, because gasdynamic models cannot produce the PDL on
the sunward side of the magnetopause.
For northward (IMF), flux tube depletion occurs in almost all the subsolar
magnetosheath.
However, the streamlines closest to the magnetopause and
the stagnation line show the greatest depletion.
The relative strength of the various MHD forces changes along these streamlines.
Forces along a flux tube at different stages of its depletion in the
magnetosheath are analyzed.
We find that a strong plasma pressure gradient force along the magnetic field
at the bow shock and a pressure gradient force along the flux tube within the magnetosheath
usually exist pushing plasma away from the equatorial plane to deplete the flux tube.
More complex force structures along the flux tube are found close to the magnetopause.
This new, more detailed description of flux tube depletion is compared with
the results of Zwan and Wolf (1976) and differences are found.
Near the magnetopause, the pressure gradient force along the flux tube either
drives plasma away from the equatorial plane or pushes plasma toward
the equatorial plane.
As a result, a slow mode structure is seen along the flux tube
which might be responsible for the observed two-layered slow mode structures.
Key words. Magnetospheric physics (magnetosheath; solar
wind-magnetosphere interactions). Space plasma physics
(numerical simulations studies) |
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