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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Comparisons between two wavelet functions in extracting coherent structures from solar wind time series

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Autor(es):
Bolzan, M. J. A. [1] ; Guarnieri, F. L. [1] ; Vieira, Paulo Cesar [1]
Número total de Autores: 3
Afiliação do(s) autor(es):
[1] UNIVAP, Inst Pesquisa & Desenvolvimento, Sao Jose Dos Campos - Brazil
Número total de Afiliações: 1
Tipo de documento: Artigo Científico
Fonte: Brazilian Journal of Physics; v. 39, n. 1, p. 12-17, MAR 2009.
Citações Web of Science: 6
Resumo

Nowadays, wavelet analysis of turbulent flows have become increasingly popular. However, the study of geometric characteristics from wavelet functions is still poorly explored. In this work we compare the performance of two wavelet functions in extracting the coherent structures from solar wind velocity time series. The data series are from years 1996 to 2002 (except 1998 and 1999). The wavelet algorithm decomposes the annual time-series in two components: the coherent part and non-coherent one, using the daubechies-4 and haar wavelet function. The threshold assumed is based on a percentage of maximum variance found in each dyadic scale. After the extracting procedure, we applied the power spectral density on the original time series and coherent time series to obtain spectral indices. The results from spectral indices show higher values for the coherent part obtained by daubechies-4 than those obtained by the haar wavelet function. Using the kurtosis statistical parameter, on coherent and non-coherent time series, it was possible to conjecture that the differences found between two wavelet functions may be associated with their geometric forms. (AU)

Processo FAPESP: 05/00511-9 - Análise estatística e ondeleta das relações Sol-Terra
Beneficiário:Maurício José Alves Bolzam
Modalidade de apoio: Auxílio à Pesquisa - Regular