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| Titel |
Simultaneous observation of traveling ionospheric disturbances in the Northern and Southern Hemispheres |
| VerfasserIn |
C. E. Valladares, J. Villalobos, M. A. Hei, R. Sheehan, Su. Basu, E. MacKenzie, P. H. Doherty, V. H. Rios |
| 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. 4 ; Nr. 27, no. 4 (2009-04-02), S.1501-1508 |
| Datensatznummer |
250016476
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| Publikation (Nr.) |
 copernicus.org/angeo-27-1501-2009.pdf |
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| Zusammenfassung |
| Measurements of total electron content (TEC) using 263 GPS receivers located
in the North and South America continents are presented to demonstrate the
simultaneous existence of traveling ionospheric disturbances (TID) at high,
mid, and low latitudes, and in both Northern and Southern Hemispheres. The
TID observations pertain to the magnetically disturbed period of 29–30 October
2003 also known as the Halloween storm. The excellent quality of the
TEC measurements makes it possible to calculate and remove the diurnal
variability of TEC and then estimate the amplitude, wavelength, spectral
characteristics of the perturbations, and the approximate velocity of the
AGW. On 29 October 2003 between 17:00 and 19:00 UT, there existed a sequence of
TEC perturbations (TECP), which were associated with the transit of
atmospheric gravity waves (AGW) propagating from both auroral regions toward
the geographic equator. A marked difference was found between the northern
and southern perturbations. In the Northern Hemisphere, the preferred
horizontal wavelength varies between 1500 and 1800 km; the propagation
velocity is near 700 m/s and the perturbation amplitude about 1 TEC unit
(TECu). South of the geographic equator the wavelength of the TECP is as
large as 2700 km, the velocity is about 550 m/s, and the TECP amplitude is 3
TECu. Concurrently with our observations, the Jicamarca digisonde observed
virtual height traces that exhibited typical features that are associated
with TIDs. Here, it is suggested that differences in the local conductivity
between northern and southern auroral ovals create a different Joule heating
energy term. The quality of these observations illustrates the merits of GPS
receivers to probe the ionosphere and thermosphere. |
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