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| Titel |
Climatology of GPS phase scintillation and HF radar backscatter for the high-latitude ionosphere under solar minimum conditions |
| VerfasserIn |
P. Prikryl, P. T. Jayachandran, S. C. Mushini, R. Chadwick |
| 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 ; 29, no. 2 ; Nr. 29, no. 2 (2011-02-22), S.377-392 |
| Datensatznummer |
250016977
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| Publikation (Nr.) |
 copernicus.org/angeo-29-377-2011.pdf |
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| Zusammenfassung |
| Maps of GPS phase scintillation at high latitudes have been constructed
after the first two years of operation of the Canadian High Arctic
Ionospheric Network (CHAIN) during the 2008–2009 solar minimum. CHAIN
consists of ten dual-frequency receivers, configured to measure amplitude
and phase scintillation from L1 GPS signals and ionospheric total electron
content (TEC) from L1 and L2 GPS signals. Those ionospheric data have been
mapped as a function of magnetic local time and geomagnetic latitude
assuming ionospheric pierce points (IPPs) at 350 km. The mean TEC depletions
are identified with the statistical high-latitude and mid-latitude troughs.
Phase scintillation occurs predominantly in the nightside auroral oval and
the ionospheric footprint of the cusp. The strongest phase scintillation is
associated with auroral arc brightening and substorms or with perturbed cusp
ionosphere. Auroral phase scintillation tends to be intermittent, localized
and of short duration, while the dayside scintillation observed for
individual satellites can stay continuously above a given threshold for
several minutes and such scintillation patches persist over a large area of
the cusp/cleft region sampled by different satellites for several hours. The
seasonal variation of the phase scintillation occurrence also differs
between the nightside auroral oval and the cusp. The auroral phase
scintillation shows an expected semiannual oscillation with equinoctial
maxima known to be associated with aurorae, while the cusp scintillation is
dominated by an annual cycle maximizing in autumn-winter. These differences
point to different irregularity production mechanisms: energetic electron
precipitation into dynamic auroral arcs versus cusp ionospheric convection
dynamics. Observations suggest anisotropy of scintillation-causing
irregularities with stronger L-shell alignment of irregularities in the cusp
while a significant component of field-aligned irregularities is found in
the nightside auroral oval. Scintillation-causing irregularities can coexist
with small-scale field-aligned irregularities resulting in HF radar
backscatter. The statistical cusp and auroral oval are characterized by the
occurrence of HF radar ionospheric backscatter and mean ground magnetic
perturbations due to ionospheric currents. |
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