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| Titel |
Multifractal analysis of vertical total electron content (VTEC) at equatorial region and low latitude, during low solar activity |
| VerfasserIn |
M. J. A. Bolzan, A. Tardelli, V. G. Pillat, P. R. Fagundes, R. R. Rosa |
| 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 ; 31, no. 1 ; Nr. 31, no. 1 (2013-01-28), S.127-133 |
| Datensatznummer |
250017742
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| Publikation (Nr.) |
 copernicus.org/angeo-31-127-2013.pdf |
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| Zusammenfassung |
| This paper analyses the multifractal aspects of the GPS data (measured
during a period of low solar activity) obtained from two Brazilian stations:
Belém (01.3° S, 48.3° W) and São José dos Campos (SJC)
(23.2° S, 45.9° W). The results show that the respective
geographic sites show important scaling differences as well as similarities
when their multifractal signatures for vertical total electron content (VTEC) are compared. The
f(α) spectra have a narrow shape for great scales, which
indicates the predominance of deterministic phenomena, such as solar
rotation (27 days) over intermittent phenomena. Furthermore, the f(α) spectra for both sites have a strong multifractality
degree at small scales. This strong multifractality degree observed at small
scales (1 to 12 h) at both sites is because the ionosphere over Brazil
is a non-equilibrium system. The differences found were that Belém
presented a stronger multifractality at small scales (1 h to 12 h)
compared with SJC, particularly in 2006. The reason for this behaviour
may be associated with the location of Belém, near the geomagnetic
equator, where at this location the actions of X-rays, ultraviolet, and
another wavelength from the Sun are more direct, strong, and constant
throughout the whole year. Although the SJC site is near ionospheric
equatorial anomaly (IEA) peaks, this interpretation could explain the higher
values found for the intermittent parameter μ for Belém compared
with SJC. Belém also showed the presence of one or two flattening
regions for f(α) spectra at the same scales mentioned before. These
differences and similarities also were interpreted in terms of the IEA
content, where this phenomenon is an important source of intermittence due
the presence of the VTEC peaks at ±20°
geomagnetic latitudes. |
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