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| Titel |
Mid-latitude ionospheric perturbation associated with the Spacelab-2 plasma depletion experiment at Millstone Hill |
| VerfasserIn |
J. C. Foster, J. M. Holt, L. J. Lanzerotti |
| 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 ; 18, no. 1 ; Nr. 18, no. 1, S.111-119 |
| Datensatznummer |
250013887
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| Publikation (Nr.) |
 copernicus.org/angeo-18-111-2000.pdf |
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| Zusammenfassung |
Elevation scans across geomagnetic mid
latitudes by the incoherent scatter radar at Millstone Hill captured the
ionospheric response to the firing of the Space Shuttle Challenger OMS thrusters
near the peak of the F layer on July 30, 1985. Details of the excitation
of airglow and the formation of an ionospheric hole during this event have been
reported in an earlier paper by Mendillo et al.. The depletion (factor
~2) near the 320 km Shuttle orbital altitude persisted for ~35 min and
then recovered to near normal levels, while at 265 km the density was reduced by
a factor of ~6; this significant reduction in the bottomside F-region
density persisted for more than 3 hours. Total electron content in the vicinity
of the hole was reduced by more than a factor of 2, and an oscillation of the F-region
densities with 40-min period ensued and persisted for several hours. Plasma
vertical Doppler velocity varied quasi-periodically with a ~80-min period,
while magnetic field variations observed on the field line through the
Shuttle-burn position exhibited a similar ~80-min periodicity. An interval of
magnetic field variations at hydromagnetic frequencies (~95 s period)
accompanied the ionospheric perturbations on this field line. Radar observations
revealed a downward phase progression of the 40-min period density enhancements
of -1.12° km-1, corresponding to a 320-km vertical wavelength. An
auroral-latitude geomagnetic disturbance began near the time of the Spacelab-2
experiment and was associated with the imposition of a strong southward IMF Bz
across the magnetosphere. This created an additional complication in the
interpretation of the active ionospheric experiment. It cannot be determined
uniquely whether the ionospheric oscillations, which followed the Spacelab-2
experiment, were related to the active experiment or were the result of a
propagating ionospheric disturbance (TID) launched by the enhanced auroral
activity. The most reasonable conclusion is that the ionospheric oscillations
were a result of the coincident geomagnetic disturbance. The pronounced
depletion of the bottomside ionosphere, however, accentuated the oscillatory
behavior during the interval following the Shuttle OMS burn..
Key words. Ionosphere (active experiments; ionospheric
disturbances) · Magnetospheric physics (storms and substorms) |
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