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| Titel |
Comparing plasma bubble occurrence rates at CHAMP and GRACE altitudes during high and low solar activity |
| VerfasserIn |
C. Xiong, J. Park, H. Lühr, C. Stolle, S. Y. Ma |
| 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 ; 28, no. 9 ; Nr. 28, no. 9 (2010-09-06), S.1647-1658 |
| Datensatznummer |
250016878
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| Publikation (Nr.) |
 copernicus.org/angeo-28-1647-2010.pdf |
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| Zusammenfassung |
| Based on the multi-year data base (2001–2009) of CHAMP Planar Langmuir Probe
(PLP) data and GRACE K-Band Ranging (KBR1B) data, typical features of
ionospheric plasma irregularities are studied at the altitudes of CHAMP
(300–400 km) and GRACE (~500 km). The phenomena we are focusing on are
the equatorial plasma bubbles (EPBs). Similar seasonal/longitudinal (S/L)
distributions of EPB have been found at both CHAMP and GRACE altitudes
during solar active and quiet years. Peak EPB occurrence rates, defined as
number of events within an S/L bin divided by the number of passes over that
bin, decrease from the high and moderate solar flux period (2001–2005) to
the low solar flux period (2005–2009) from 80% to 60% and 60% to
40% at CHAMP and GRACE altitudes, respectively. On average the occurrence
rate increases linearly with solar flux at about the same rate at CHAMP and
GRACE. For high flux levels (P10.7>200) non-linear increases are observed
at GRACE. The occurrence rate increases rapidly after 19:00 local time (LT)
during high solar flux periods. Around solar minimum rates increase more
gently and peak around 22:00 LT. The highest occurrence rates are encountered
at latitudes around 10° north and south of the dip equator. Results
from the two altitudes support the notion that EPBs form regions of depleted
plasma along geomagnetic fluxtubes. It is shown for the first time that in
regions of high occurrence rates EPBs are associated with fluxtubes reaching
greater apex heights than those in regions of low rates. |
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