Equatorial spread-F occurrence observed at two near equatorial stations in the Brazilian sector and its occurrence modulated by planetary waves
Tipo
Artigo
Data de publicação
2011
Periódico
Journal of Atmospheric and Solar-Terrestrial Physics
Citações (Scopus)
17
Autores
Bertoni F.C.P.
Sahai Y.
Raulin J.-P.
Fagundes P.R.
Pillat V.G.
Gimenez de Castro C.G.
Lima W.L.C.
Sahai Y.
Raulin J.-P.
Fagundes P.R.
Pillat V.G.
Gimenez de Castro C.G.
Lima W.L.C.
Orientador
Título da Revista
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Título de Volume
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Programa
Resumo
In this work, we present a study on the ionospheric Equatorial Spread-F (ESF) occurrence and morphologic features, based on measurements made during the period of October 2005 and January 2006 and May-July 2006 by digital ionosondes operating at two near magnetic equator locations, namely, Palmas (10.2°S, 48.2°W; dip lat. 5.5°S) and Manaus (3.1°S, 60.0°W; dip lat. 6.4°N), Brazil. The ionospheric height related parameter (h'. F), the ionospheric density related parameter (foF2), and the dynamo-electric fields inferred from h'. F time derivative (d. h'. F/d. t) were analyzed with wavelets transform. The results exhibit periodic nature with wave-like signatures of 12-16 days. On the other hand, the electron density time variability (d. Ne/d. t) was also analyzed using wavelets transform, and it presented planetary wave modulation with episodic nature. The ESF start time variability demonstrates to have a periodic signature of approximately 15 days with a good significance level, and it has a tendency to be anti-correlated with the pre-reversal enhancement time velocity (d. h'. F/d. t), showing that larger vertical drift velocities (ionospheric uplift) may contribute to generate earlier ESF occurrence. © 2010 Elsevier Ltd.
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Assuntos Scopus
Digital ionosondes , Drift velocities , Electron densities , Equatorial ionosphere , Equatorial spread F , Ionosonde , Ionospheric heights , Ionospheric plasma irregularities , Magnetic equator , Planetary Waves , Time derivative , Time variability , Wavelets transform