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| Titel |
Quiet-time Pc 5 pulsations in the Earth's magnetotail: IMP-8, ISEE-1 and ISEE-3 simultaneous observations |
| VerfasserIn |
D. V. Sarafopoulos, E. T. Sarris |
| 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 ; 12, no. 2/3 ; Nr. 12, no. 2/3, S.121-138 |
| Datensatznummer |
250010314
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| Publikation (Nr.) |
 copernicus.org/angeo-12-121-1994.pdf |
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| Zusammenfassung |
| Quasi-periodic Pc 5 pulsations have been
reported inside and just outside the Earth's magnetotail during intervals of low
geomagnetic activity. In order to further define their characteristics and
spatial extent, we present three case studies of simultaneous magnetic field and
plasma observations by IMP-8, ISEE-1 (and ISEE-2 in one case) in the Earth's
magnetotail and ISEE-3 far upstream of the bow shock, during intervals in which
the spacecraft were widely separated. In the first case study, similar
pulsations are observed by IMP-8 at the dawn flank of the plasma sheet and by
ISEE-1 near the plasma sheet boundary layer (PSBL) near midnight local time. In
the second case study, simultaneous pulsations are observed by IMP-8 in the dusk
magnetosheath and by ISEE-1 and 2 in the dawn plasma sheet. In the third case
study, simultaneous pulsations are observed in the north plasma sheet boundary
layer and the south plasma sheet. We conclude that the pulsations occur
simultaneously throughout much of the nightside magnetosphere and the
surrounding magnetosheath, i.e. that they have a global character. Some
additional findings are the following: (a) the observed pulsations are mixed
mode compressional and transverse, where the compressional character is more
apparent in the close vicinity of the plane ZGSM=0; (b) the
compressional pulsations of the magnetic field in the dusk magnetosheath show
peaks that coincide (almost one-to-one) with similar peaks observed inside the
dawn plasma sheet; (c) in the second case study the polarization sense of the
magnetic field and the recurrent left-hand plasma vortices observed in the dawn
plasma sheet are consistent with anti-sunward moving waves on the magneto-pause;
(d) pulsation amplitudes are weaker in the PSBL(or lobe) as compared with those
in the magneto-tail's flanks, suggesting a decay with distance from the
magnetopause; (e) the thickness of the plasma sheet (under extremely quiet
conditions) is estimated to be ~22 RE at an average location
of (X, Y)GSM=(16, 17) RE, whereas at
midnight local time the thickness is ~14 RE. The detected
pulsations are probably due to the pressure variations (recorded by ISEE-3) in
the solar wind, and/or the Kelvin Helmholtz instability in the low-latitude
boundary layer or the magnetopause due to a strongly northward IMF. |
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