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| Titel |
Interhemispheric comparison of GPS phase scintillation at high latitudes during the magnetic-cloud-induced geomagnetic storm of 5–7 April 2010 |
| VerfasserIn |
P. Prikryl, L. Spogli, P. T. Jayachandran, J. Kinrade, C. N. Mitchell, B. Ning, G. Li, P. J. Cilliers, M. Terkildsen, D. W. Danskin, E. Spanswick, E. Donovan, A. T. Weatherwax, W. A. Bristow, L. Alfonsi, G. Franceschi, V. Romano, C. M. Ngwira, B. D. L. Opperman |
| 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. 12 ; Nr. 29, no. 12 (2011-12-21), S.2287-2304 |
| Datensatznummer |
250017146
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| Publikation (Nr.) |
 copernicus.org/angeo-29-2287-2011.pdf |
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| Zusammenfassung |
| Arrays of GPS Ionospheric Scintillation and TEC Monitors (GISTMs) are used
in a comparative scintillation study focusing on quasi-conjugate pairs of
GPS receivers in the Arctic and Antarctic. Intense GPS phase scintillation
and rapid variations in ionospheric total electron content (TEC) that can
result in cycle slips were observed at high latitudes with dual-frequency
GPS receivers during the first significant geomagnetic storm of solar cycle
24 on 5–7 April 2010. The impact of a bipolar magnetic cloud of north-south
(NS) type embedded in high speed solar wind from a coronal hole caused a
geomagnetic storm with maximum 3-hourly Kp = 8- and hourly ring current Dst = −73 nT. The interhemispheric comparison of phase scintillation reveals
similarities but also asymmetries of the ionospheric response in the
northern and southern auroral zones, cusps and polar caps. In the nightside
auroral oval and in the cusp/cleft sectors the phase scintillation was
observed in both hemispheres at about the same times and was correlated with
geomagnetic activity. The scintillation level was very similar in
approximately conjugate locations in Qiqiktarjuaq (75.4° N; 23.4° E
CGM lat. and lon.) and South Pole (74.1° S; 18.9° E), in Longyearbyen
(75.3° N; 111.2° E) and Zhongshan (74.7° S; 96.7° E), while it
was significantly higher in Cambridge Bay (77.0° N; 310.1° E) than at
Mario Zucchelli (80.0° S; 307.7° E). In the polar cap, when the
interplanetary magnetic field (IMF) was strongly northward, the ionization
due to energetic particle precipitation was a likely cause of scintillation
that was stronger at Concordia (88.8° S; 54.4° E) in the dark
ionosphere than in the sunlit ionosphere over Eureka (88.1° N; 333.4° E),
due to a difference in ionospheric conductivity. When the IMF tilted
southward, weak or no significant scintillation was detected in the northern
polar cap, while in the southern polar cap rapidly varying TEC and strong
phase scintillation persisted for many hours. This interhemispheric
asymmetry is explained by the difference in the location of solar terminator
relative to the cusps in the Northern and Southern Hemisphere. Solar
terminator was in the immediate proximity of the cusp in the Southern
Hemisphere where sunlit ionospheric plasma was readily convected into the
central polar cap and a long series of patches was observed. In contrast,
solar terminator was far poleward of the northern cusp thus reducing the
entry of sunlit plasma and formation of dense patches. This is consistent
with the observed and modeled seasonal variation in occurrence of polar cap
patches. The GPS scintillation and TEC data analysis is supported by data
from ground-based networks of magnetometers, riometers, ionosondes, HF
radars and all-sky imagers, as well as particle flux measurements by DMSP
satellites. |
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