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| Titel |
Dispersive O+ conics observed in the plasma-sheet boundary layer with CRRES/LOMICS during a magnetic storm |
| VerfasserIn |
M. Wüest, D. T. Young, M. F. Thomsen, B. L. Barraclough, H. J. Singer, R. R. Anderson |
| 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 ; 14, no. 6 ; Nr. 14, no. 6, S.593-607 |
| Datensatznummer |
250012319
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| Publikation (Nr.) |
 copernicus.org/angeo-14-593-1996.pdf |
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| Zusammenfassung |
| We present initial results from the
Low-energy magnetospheric ion composition sensor (LOMICS) on the Combined
release and radiation effects satellite (CRRES) together with electron, magnetic
field, and electric field wave data. LOMICS measures all important
magnetospheric ion species (H+, He++, He+, O++,
O+) simultaneously in the energy range 60 eV to 45 keV, as well as
their pitch-angle distributions, within the time resolution afforded by the
spacecraft spin period of 30 s. During the geomagnetic storm of 9 July 1991,
over a period of 42 min (0734 UT to 0816 UT) the LOMICS ion mass spectrometer
observed an apparent O+ conic flowing away from the southern
hemisphere with a bulk velocity that decreased exponentially with time from 300
km/s to 50 km/s, while its temperature also decreased exponentially from 700 to
5 eV. At the onset of the O+ conic, intense low-frequency
electromagnetic wave activity and strong pitch-angle scattering were also
observed. At the time of the observations the CRRES spacecraft was inbound at L~7.5
near dusk, magnetic local time (MLT), and at a magnetic latitude of –23°. Our
analysis using several CRRES instruments suggests that the spacecraft was
skimming along the plasma sheet boundary layer (PSBL) when the upward-flowing
ion conic arrived. The conic appears to have evolved in time, both slowing and
cooling, due to wave-particle interactions. We are unable to conclude whether
the conic was causally associated with spatial structures of the PSBL or the
central plasma sheet. |
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