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| Titel |
Energetic particle sounding of the magnetospheric cusp with ISEE-1 |
| VerfasserIn |
K. E. Whitaker, T. A. Fritz, J. Chen, M. Klida |
| 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 ; 25, no. 5 ; Nr. 25, no. 5 (2007-06-04), S.1175-1182 |
| Datensatznummer |
250015848
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| Publikation (Nr.) |
 copernicus.org/angeo-25-1175-2007.pdf |
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| Zusammenfassung |
| Observations on 30 October 1978 show the ISEE-1 spacecraft
passing though the high-altitude dayside northern magnetospheric cusp
region from
roughly 16:00 to 18:30 UT, during a slow solar wind period (~380 km/s).
More than two orders of magnitude enhancements of the cusp energetic
particle (CEP) fluxes were observed along with a depressed and turbulent
local magnetic field. The observed variations of
the pitch angle distributions (PAD)
provide a unique opportunity to determine the structure of the cusp
and the origin of the CEP.
Through a boundary sounding technique, the location and orientation of
the cusp poleward (or backside) boundary was observed for almost 10 min
during which time it appeared initially to be stationary in the
GSM/GSE X-direction and then moved
sunward about 0.12 Earth radii (RE). The orientation remained
approximately perpendicular to the GSM/GSE X-axis until it was
observed to rotate by 60 degrees in ~3 min before ISEE-1
was fully inside the cusp cavity. The cavity itself was filled
with CEP fluxes displaying large anisotropies, indicative
of their source being located below (Earthward) of the satellite location.
The spacecraft entered from the backside of the cusp,
then traveled ~4 RE through the cavity,
and exited through the "top" of the cavity
leaving a region of energetic ions below.
The PADs demonstrate that the bow shock cannot be
the main source of the observed CEPs.
The CEP fluxes were measured at about 8.5 h MLT when the IMF had
both an 8–10 nT duskward and southward component. |
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