Variability of the lunar semidiurnal tidal amplitudes in the ionosphere over Brazil
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Published:2021-02-17
Issue:1
Volume:39
Page:151-164
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ISSN:1432-0576
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Container-title:Annales Geophysicae
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language:en
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Short-container-title:Ann. Geophys.
Author:
Paulino Ana RobertaORCID, Araújo Fabiano da Silva, Paulino IgoORCID, Wrasse Cristiano Max, Lima Lourivaldo Mota, Batista Paulo PradoORCID, Batista Inez StaciariniORCID
Abstract
Abstract. The variability in the amplitudes of the lunar semidiurnal tide was investigated using maps of total electron content over Brazil from January 2011 to December 2014. Long-period variability showed that the annual variation is always present in all investigated magnetic latitudes, and it represents the main component of the temporal variability. Semiannual and triannual (two and three times a year, respectively) oscillations were the second and third components, respectively, but they presented significant temporal and spatial variability without a well-defined pattern. Among the short-period oscillations in the amplitude of the lunar tide, the most pronounced ones were concentrated between 7–11 d. These oscillations were stronger around the equinoxes, in particular between September and November in almost all latitudes. In some years, as in 2013 and 2014, for instance, they appeared with a large power spectral density in the winter hemisphere. These observed short-period oscillations could be a result of a direct modulation of the lunar semidiurnal tide by planetary waves from the lower atmosphere and/or due to electrodynamic coupling of E and F regions of the ionosphere.
Funder
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Conselho Nacional de Desenvolvimento Científico e Tecnológico
Publisher
Copernicus GmbH
Subject
Space and Planetary Science,Earth and Planetary Sciences (miscellaneous),Atmospheric Science,Geology,Astronomy and Astrophysics
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