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| Titel |
Modulation of nightside polar patches by substorm activity |
| VerfasserIn |
A. G. Wood, S. E. Pryse, J. Moen |
| 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 ; 27, no. 10 ; Nr. 27, no. 10 (2009-10-13), S.3923-3932 |
| Datensatznummer |
250016680
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| Publikation (Nr.) |
 copernicus.org/angeo-27-3923-2009.pdf |
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| Zusammenfassung |
| Results are presented from a multi-instrument study showing the influence of
geomagnetic substorm activity on the spatial distribution of the
high-latitude ionospheric plasma. Incoherent scatter radar and radio
tomography measurements on 12 December 2001 were used to directly observe
the remnants of polar patches in the nightside ionosphere and to investigate
their characteristics. The patches occurred under conditions of IMF Bz
negative and IMF By negative. They were attributed to dayside
photoionisation transported by the high-latitude convection pattern across
the polar cap and into the nighttime European sector. The patches on the
nightside were separated by some 5° latitude during substorm expansion,
but this was reduced to some 2° when the activity had subsided. The
different patch separations resulted from the expansion and contraction of
the high-latitude plasma convection pattern on the nightside in response to
the substorm activity. The patches of larger separation occurred in the
antisunward cross-polar flow as it entered the nightside sector. Those of
smaller separation were also in antisunward flow, but close to the
equatorward edge of the convection pattern, in the slower, diverging flow at
the Harang discontinuity. A patch repetition time of some 10 to 30 min was
estimated depending on the phase of the substorm. |
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