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On signal-noise decomposition of time-series using the continuous wavelet transform: application to sunspot index

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dc.contributor.author Polygiannakis, J en
dc.contributor.author Preka-Papadema, P en
dc.contributor.author Moussas, X en
dc.date.accessioned 2014-03-01T11:45:50Z
dc.date.available 2014-03-01T11:45:50Z
dc.date.issued 2003 en
dc.identifier.issn 0035-8711 en
dc.identifier.uri https://dspace.lib.ntua.gr/xmlui/handle/123456789/37648
dc.subject methods : data analysis en
dc.subject methods : numerical en
dc.subject Sun : activity en
dc.subject sunspots en
dc.subject.classification Astronomy & Astrophysics en
dc.subject.other QUASI-BIENNIAL OSCILLATION en
dc.subject.other STELLAR DIFFERENTIAL ROTATION en
dc.subject.other SOLAR CONVECTION ZONE en
dc.subject.other AUTOMATA CA MODELS en
dc.subject.other MAUNDER MINIMUM en
dc.subject.other EARTHS ROTATION en
dc.subject.other DAY PERIODICITY en
dc.subject.other MAGNETIC-FIELD en
dc.subject.other MULTIFRACTAL FORMALISM en
dc.subject.other REGION OSCILLATIONS en
dc.title On signal-noise decomposition of time-series using the continuous wavelet transform: application to sunspot index en
heal.type other en
heal.language English en
heal.publicationDate 2003 en
heal.abstract We show that the continuous wavelet transform can provide a unique decomposition of a time-series into 'signal-like' and 'noise-like' components. From the overall wavelet spectrum, two mutually independent skeleton spectra can be extracted, allowing the separate detection and monitoring in even non-stationary time-series of the evolution of (i) both stable but also transient, evolving periodicities, such as the output of low-dimensional dynamical systems, and (ii) scale-invariant structures, such as discontinuities, self-similar structures or noise. The idea of the method is to keep from the overall wavelet expansion of the time-series only the wavelet components of locally maximal amplitude at any given time or scale, thus obtaining the instantly maximal and scale maximal wavelet skeleton spectrum, respectively. The scale maximal spectrum was previously proposed for studying possible multifractal scaling properties of time-series. The instantly maximal spectrum proposed here exhibits clearer spectral peaks and reduced noise, as compared to the overall wavelet spectrum. An indicative application to the monthly-averaged sunspot index reveals, apart from the well-known 11-yr periodicity, three of its harmonics, the 2-yr periodicity (quasi-biennial oscillation, QBO ) and several more (some of which have been detected previously in various solar, Earth-solar connection and climate indices), here proposed as just harmonics of the QBO, in all supporting the double-cycle solar magnetic dynamo model. The scale maximal spectrum reveals the presence of 1/f fluctuations with time-scales up to 1 yr in the sunspot number, indicating that the solar magnetic configurations involved in the transient solar activity phenomena with those characteristic time-scales are in a self-organized critical state, as previously proposed for the solar flare occurrence. en
heal.publisher BLACKWELL PUBLISHING LTD en
heal.journalName MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY en
dc.identifier.isi ISI:000184485500011 en
dc.identifier.volume 343 en
dc.identifier.issue 3 en
dc.identifier.spage 725 en
dc.identifier.epage 734 en


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