Wavelet-based filtering of intermittent events from geomagnetic time-series

Kovács, Péter; Carbone, Vincenzo; Vörös, Z.

doi:10.1016/s0032-0633(01)00063-0

Cited by 39 publications

(56 citation statements)

References 32 publications

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“…Some previous works have demonstrated the statistical self-affinity properties observed in the geomagnetic times series (Chang, 1999;Sitnov et al, 2001;Uritsky et al, 2001Uritsky et al, , 2006Kovacs et al, 2001;Lui, 2002;Wanliss, 2005a;Balasis et al, 2006;Wanliss and Dobias, 2007).…”

Section: Introductionmentioning

confidence: 96%

“…With a local decomposition of a multiscale signal, wavelet analysis is particularly suited to detect and follow the time evolution of the frequency distribution of a given time series (Ivanov et al, 2001;Kovacs et al, 2001;Lui, 2002;Mendes et al, 2005;Mandea and Balasis, 2006;Zaourar et al, 2006;Gaci et al, 2010). This property is particularly important when one considers non-stationary processes.…”

Section: Introductionmentioning

confidence: 99%

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Wavelet-based multiscale analysis of geomagnetic disturbance

Zaourar¹,

Hamoudi²,

Mandéa

et al. 2013

Earth Planet Sp

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The dynamics of external contributions to the geomagnetic field is investigated by applying time-frequency methods to magnetic observatory data. Fractal models and multiscale analysis enable obtaining maximum quantitative information related to the short-term dynamics of the geomagnetic field activity. The stochastic properties of the horizontal component of the transient external field are determined by searching for scaling laws in the power spectra. The spectrum fits a power law with a scaling exponent β, a typical characteristic of self-affine time-series. Local variations in the power-law exponent are investigated by applying wavelet analysis to the same time-series. These analyses highlight the self-affine properties of geomagnetic perturbations and their persistence. Moreover, they show that the main phases of sudden storm disturbances are uniquely characterized by a scaling exponent varying between 1 and 3, possibly related to the energy contained in the external field. These new findings suggest the existence of a long-range dependence, the scaling exponent being an efficient indicator of geomagnetic activity and singularity detection. These results show that by using magnetogram regularity to reflect the magnetosphere activity, a theoretical analysis of the external geomagnetic field based on local power-law exponents is possible.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Wavelet-based multiscale analysis of geomagnetic disturbance

Zaourar¹,

Hamoudi²,

Mandéa

et al. 2013

Earth Planet Sp

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“…Another observable property of the magnetospheric dynamics, which is documented in literature, is the intermittent character of geomagnetic time series, i.e., the anomalous scaling of small-scale increments (fluctuations) and the presence of a multifractal character (see, e.g., Consolini et al, 1996;Consolini and De Michelis, 1998;Kovács et al, 2001;Wanliss et al, 2005;Consolini and De Michelis, 2011, etc.). This intermittent character seems to be a common property of magnetospheric dynamics that is generally observed in both the time series of geomagnetic indices and in situ magnetospheric and ground-based magnetic field measurements.…”

Section: Introductionmentioning

confidence: 99%

Intermittency and multifractional Brownian character of geomagnetic time series

Consolini

Marco

Michelis

2013

Nonlin. Processes Geophys.

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The Earth's magnetosphere exhibits a complex behavior in response to the solar wind conditions. This behavior, which is described in terms of mutifractional Brownian motions, could be the consequence of the occurrence of dynamical phase transitions. On the other hand, it has been shown that the dynamics of the geomagnetic signals is also characterized by intermittency at the smallest temporal scales. Here, we focus on the existence of a possible relationship in the geomagnetic time series between the multifractional Brownian motion character and the occurrence of intermittency. In detail, we investigate the multifractional nature of two long time series of the horizontal intensity of the Earth's magnetic field as measured at L'Aquila Geomagnetic Observatory during two years (2001 and 2008), which correspond to different conditions of solar activity. We propose a possible double origin of the intermittent character of the small-scale magnetic field fluctuations, which is related to both the multifractional nature of the geomagnetic field and the intermittent character of the disturbance level. Our results suggest a more complex nature of the geomagnetic response to solar wind changes than previously thought

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“…In the present context, as suggested by Kovács et al (2001), neglecting the detailed reason for the evolution of the geomagnetic disturbances (storms or substorms) the fluctuating nature of the field can be interpreted, in a general framework, as the manifestation of turbulent phenomena that take place within the complex magnetosphere MHD configuration. Usually, turbulence is interpreted by means of structure functions following power-laws in the inertial range of the energy spectra.…”

Section: Methodsmentioning

confidence: 90%

“…In fact, the systematic study of the statistical properties of nonlinear magnetosphere variability and their relations to the solar activity, as the solar wind, has attracted a growing interest (e.g. Chapman et al, 1998;Chang, 1999;Kovács et al, 2001;Lui, 2002;Vörös et al, 2002;Balasis et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Multifractal analysis of low-latitude geomagnetic fluctuations

2009

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Abstract.The technique of large deviation multifractal spectrum has shown that the high-latitude (77.5 • N, 69.2 • W) geomagnetic fluctuations can be described from direct dissipation process or loading-unloading regimes of the solar windmagnetosphere coupling. In this paper, we analyze the Hcomponent of low-latitude (22.4 • S, 43.6 • W) geomagnetic field variability observed during the month of July 2000 at the Geomagnetic Observatory, Vassouras, RJ, Brazil. The variability pattern during this period is a mixture of quiet and disturbed days including the Bastille Day intense geomagnetic storm on 15 July. Due to the complexity of this data, we pursue a detailed analysis of the geomagnetic fluctuations in different time scales including a multifractal approach using the singular power spectrum deviations obtained from the wavelet transform modulus maxima (WTMM). The results suggest, as observed from high-latitude data, the occurrence of low-latitude multifractal processes driving the intermittent coupling between the solar wind-magnetosphere and geomagnetic field variations. On finer scales possible physical mechanisms in the context of nonlinear magnetosphere response are discussed.

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Wavelet-based filtering of intermittent events from geomagnetic time-series

Cited by 39 publications

References 32 publications

Wavelet-based multiscale analysis of geomagnetic disturbance

Wavelet-based multiscale analysis of geomagnetic disturbance

Intermittency and multifractional Brownian character of geomagnetic time series

Multifractal analysis of low-latitude geomagnetic fluctuations

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