Study of ultra low frequency waves in the magnetosheath of Venus
Study of Jupiter magnetospheric auroral radio activity variability
STUDY ON THE GEOMAGNETIC VARIATIONS USING WAVELET TECHNIQUES.
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| Author(s): |
Total Authors: 3
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| Affiliation: | [1] UNIVAP, Inst Pesquisa & Desenvolvimento, Sao Jose Dos Campos - Brazil
Total Affiliations: 1
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| Document type: | Journal article |
| Source: | Brazilian Journal of Physics; v. 39, n. 1, p. 12-17, MAR 2009. |
| Web of Science Citations: | 6 |
| Abstract | |
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) | |
| FAPESP's process: | 05/00511-9 - Wavelet and statistical analysis of solar-terrestrial relations |
| Grantee: | Maurício José Alves Bolzam |
| Support Opportunities: | Regular Research Grants |