Resumo

HANSEN, Roberta  e  SEOANE, Rafael. Multifractal analysis of the time series of daily flow values in Neuquén river. Geoacta [online]. 2013, vol.38, n.2, pp.168-182. ISSN 1852-7744.

By means of the Multifractal Analysis (AM), a study of the variability of the behaviour pattern of daily mean flow values in the Neuquén River is presented, which was recorded in Paso de Indios station for a period of one hundred years (1911-2011). The AM describes the invariant scale properties in time series. The Multifractal Spectrum (EM) is a function of the Hölder exponents of the system, which characterize the irregularity degree of the signal, its most significant parameters being like a =fingerprint' of the process. There are several versions for computing this spectrum, which are not equivalent, and among which the Legendre or thermodynamic spectrum, fL, is the most used in the applications. For this research the data of the whole series and of the different subseries is analyzed by dividing them into decades and into periods of twenty years. fL is calculated for all of them and, shifting from standard AM, another spectrum called by-definition spectrum, fD is also calculated, since it gives a more geometrical description of the singularity structure. The parameters of fD and fL are compared with the variation of the Hurst exponents of the series, and with a climate predictability index. The resulting evidences exhibit the presence of qualitative changes in the pattern of the flows regime behavior, mostly in the last decade of the XX century.

Palavras-chave : Multifractal spectrum; Daily mean flow values; Hölder exponents; Bi-multifractality; Predictability index.

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