| Texto completo | |
| Autor(es): |
Número total de Autores: 5
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| Tipo de documento: | Artigo Científico |
| Fonte: | Computers & Geosciences; v. 30, n. 8, p. 797-808, Aug. 2004. |
| Área do conhecimento: | Engenharias - Engenharia Elétrica |
| Assunto(s): | Geomagnetismo Polarização |
| Resumo | |
Spectral and polarization parameters of geomagnetic pulsations are computed from geomagnetic data recorded at ground station, using multitaper and singular value decomposition (SVD) analysis. These techniques were adapted to provide appropriate polarization parameters of pulsations. The spectra are comparable to those obtained from classical methods, but the dynamic spectra of degree of polarization present more localized spectral information, allowing easier identification of polarized pulsation events mixed to noise, which are associated by coherent sources of MHD waves. The time-frequency polarization parameters of polarized pulsations show different signatures to regular and irregular pulsation events, and the multiwavelet polarization method is used to compare with multitaper. The regular pulsation events showed to be more continuous on time with a narrow spectral frequency band, while the irregular events showed to be more localized on time with a wide spectral frequency band. The dynamic analysis of multitaper method is indicated to characterize regular pulsations and the time-frequency analysis of multiwavelet method efficiently detects irregular pulsations. The continuous multiwavelet analysis of ellipticity and azimuth is useful in progressively monitoring the propagations of MHD waves in the magnetosphere, mainly in the irregular pulsations as observed on the magnetic storm of March 24, 1991. (AU) | |
| Processo FAPESP: | 97/13374-1 - Caracterização de regimes complexos em sistemas dissipativos auto-organizados |
| Beneficiário: | Reinaldo Roberto Rosa |
| Modalidade de apoio: | Auxílio à Pesquisa - Jovens Pesquisadores |
| Processo FAPESP: | 00/10043-9 - Análise de sinais complexos no domínio temporal e espectral |
| Beneficiário: | Ademilson Zanandrea |
| Modalidade de apoio: | Auxílio à Pesquisa - Jovens Pesquisadores |