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| Titel |
Simultaneous measurements from the Millstone Hill radar and the Active satellite during the SAID/SAR arc event of the March 1990 CEDAR storm |
| VerfasserIn |
M. Forster, J. C. Foster, J. Smilauer, K. Kudela, A. V. Mikhailov |
| 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 ; 17, no. 3 ; Nr. 17, no. 3, S.389-404 |
| Datensatznummer |
250013694
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| Publikation (Nr.) |
 copernicus.org/angeo-17-389-1999.pdf |
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| Zusammenfassung |
During a nearby passage of the Active
satellite above the Millstone Hill radar on 21 March 1990 at local sunset, the
satellite and the radar performed simultaneous measurements of upper ionospheric
parameters in nearly the same spatial volume. For this purpose the radar carried
out a special azimuth-elevation scan to track the satellite. Direct comparisons
of radar data and in situ satellite measurements have been carried out quite
rarely. In this case, the coincidence of co-ordinated measurements and active
ionospheric-magnetospheric processes during an extended storm recovery phase
presents a unique occasion resulting in a very valuable data set. The
measurements show generally good agreement both during quiet prestorm and storm
conditions and the combination of radar and satellite observations gives a more
comprehensive picture of the physical processes involved. We find a close
relationship between the rapid westward ion drift peak at subauroral latitudes
(SAID event) and the occurrence of a stable auroral red (SAR) arc observed after
sunset by an all-sky imager and reported in an earlier study of this event. The
SAID electric field is caused by the penetration of energetic ions with energies
between about 1 keV and 100 keV into the outer plasmasphere to a latitude
equatorward of the extent of the plasmasheet electrons. Charge separation
results in the observed polarisation field and the SAID. Unusually high
molecular ion densities measured by the satellite at altitudes of 700-870 km at
subauroral and auroral latitudes point on strong upward-directed ion
acceleration processes and an intense neutral gas upwelling. These structures
are collocated with a narrow trough in electron density and an electron
temperature peak as observed simultaneously by the radar and the satellite
probes.
Key words. Ionosphere (ionosphere-magnetosphere
interactions; plasma temperature and density); Magnetospheric physics
(plasmasphere). |
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