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Titel |
TEC variations during low solar activity period (2005-2007) near the Equatorial Ionospheric Anomaly Crest region in India |
VerfasserIn |
Mala S. Bagiya, H. P. Joshi, K. N. Iyer, M. Aggarwal, S. Ravindran, B. M. Pathan |
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. 3 ; Nr. 27, no. 3 (2009-03-02), S.1047-1057 |
Datensatznummer |
250016438
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Publikation (Nr.) |
copernicus.org/angeo-27-1047-2009.pdf |
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Zusammenfassung |
The dual frequency signals from the GPS satellites recorded at Rajkot
(22.29° N, 70.74° E, Geographic, 14.03° N Geomagnetic) near the
Equatorial ionization anomaly crest in India have been analyzed to study the
ionospheric variations in terms of Total Electron Content (TEC) for the low solar activity period
from April 2005 to December 2007. In this study, we describe the diurnal and
seasonal variations of TEC, solar activity dependence of TEC and effects of
a space weather related event, a geomagnetic storm on TEC. The diurnal
variation of TEC shows pre-dawn minimum for a short period of time, followed
by a steep early morning increase and then reaches maximum value between 14:00 LT
and 16:00 LT. The mean diurnal variations during different seasons are
brought out. It is found that TEC at Rajkot is at its maximum during Equinoctial
months (March, April, September, October), and minimum during the Winter
months (November, December, January, February), with intermediate values
during Summer months (May, June, July, August), showing a semi annual
variation. TEC values have been decreasing since 2005, onwards showing positive
correlation with solar activity. TEC variations during the geomagnetic storm
commencing 24 August 2005 with Dst=−216 nT are analysed. TEC shows
a positive ionospheric storm effect on the first day of the storm and negative
ionospheric storm effect on the next day. The equatorial Electrojet control
on the development of the equatorial anomaly is also demonstrated. |
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