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Hada, Tohru; Koga, D.; Yamamoto, Eiko

doi:10.1023/a:1025506124402

Cited by 72 publications

(35 citation statements)

References 6 publications

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“…Observational evidence in support of this finding in space plasma turbulence was obtained by Hada et al (2003), Koga and Hada (2003) and Koga et al (2007Koga et al ( , 2008 using the Geotail solar wind data upstream and downstream of Earth's bow shock, by Sahraoui (2008) using the Cluster data in the magnetosheath close to the Earth's magnetopause, and by Telloni et al (2009) using the SOHO data of solar corona; and in atmosphere turbulence by Chian et al (2008) using the Amazon forest data.…”

Section: Introductionmentioning

confidence: 77%

Cluster and ACE observations of phase synchronization in intermittent magnetic field turbulence: a comparative study of shocked and unshocked solar wind

Chian

Miranda

2009

Ann. Geophys.

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Abstract. We apply two distinct nonlinear techniques, kurtosis and phase coherence index, to analyze the modulus of interplanetary magnetic field data |B| measured by Cluster and ACE spacecraft from 1 to 3 February 2002. High degree of phase synchronization is found across a wide range of time scales, from 1 s to 10 4 s, in the magnetic field fluctuations, both in the shocked solar wind upstream of Earth's bow shock and in the unshocked ambient solar wind at the L1 Lagrangian point. This is the first direct measurement of phase coherence in the ambient solar wind turbulence. We show that phase synchronization related to nonlinear multiscale interactions is the origin of the departure from Gaussianity in the intermittent magnetic field turbulence. In particular, we demonstrate that at small scales near the spectral break the intermittency level of Cluster is lower than ACE, which may be a signature of the reflected ions from the shock.

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Section: Introductionmentioning

confidence: 77%

Cluster and ACE observations of phase synchronization in intermittent magnetic field turbulence: a comparative study of shocked and unshocked solar wind

Chian

Miranda

2009

Ann. Geophys.

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“…The PCI was first introduced in Hada et al (2003) and in order to evaluate the degree of phase coherence among Fourier modes. In essence, this technique involves the construction of two surrogate data sets from an original N-dimensional data set.…”

Section: Phase Coherence Techniquementioning

confidence: 99%

“…Another technique to investigate phase information, used thus far in the context of the solar wind community, is the socalled phase coherence index (PCI, see Hada et al 2003;Koga et al 2007;Chian et al 2008Chian et al , 2010. The PCI employs two surrogate data sets: one in which the phase information in an image or signal is randomized and another in which the phase information is perfectly correlated.…”

Section: Introductionmentioning

confidence: 99%

The Phase Coherence of Interstellar Density Fluctuations

Burkhart

Lazarían

2016

ApJ

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Studies of MHD turbulence often investigate the Fourier power spectrum to provide information on the nature of the turbulence cascade. However, the Fourier power spectrum only contains the Fourier amplitudes and rejects all information regarding the Fourier phases. Here, we investigate the utility of two statistical diagnostics for recovering information on Fourier phases in ISM column density maps: the averaged amplitudes of the bispectrum and the phase coherence index (PCI), a new phase technique for the ISM. We create three-dimensional density and two-dimensional column density maps using a set of simulations of isothermal ideal MHD turbulence with a wide range of sonic and Alfvénic Mach numbers. We find that the bispectrum averaged along different angles with respect to either the k 1 or k 2 axis is primarily sensitive to the sonic Mach number while averaging the bispectral amplitudes over different annuli is sensitive to both the sonic and Alfvénic Mach numbers. The PCI of density suggests that the most correlated phases occur in supersonic sub-Alfvénic turbulence and near the shock scale. This suggests that nonlinear interactions with correlated phases are strongest in shock-dominated regions, in agreement with findings from the solar wind. Our results suggest that the phase information contained in the bispectrum and PCI can be used to find the turbulence parameters in column density maps.

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“…The degree of non-Gaussianity (intermittency) in a turbulence can be quantified by calculating kurtosis (i.e., flatness minus 3), which is defined as the normalized fourth-order structure function based on two-point differences in space (r) or time (τ ) assuming Taylor hypothesis. Recently, a phase coherence surrogate technique for characterizing phase synchronization in turbulence based on the null hypothesis was developed for space plasmas (Hada et al, 2003). The link between non-Gaussianity and phase synchronization in intermittent turbulence was established by Koga et al (2007) using the Geotail magnetic field data upstream and downstream of the Earth's bow shock.…”

Section: Introductionmentioning

confidence: 99%

“…The active region, on the other hand, displays an increase of kurtosis as the spatial scale r decreases, which is a characteristic of a non-Gaussian process related to nonlinear energy cascade within the inertial subrange, and these values are higher than those obtained from the quiet region for scales < ∼20 pixels ∼ 29 Mm. The degree of phase synchronization measured by the phase coherence index (Hada et al, 2003;Koga et al, 2007;Chian & Miranda, 2009) in the active region increases with decreasing spatial scale r, while the quiet region presents low-degree of synchronization at all scales. Note that at large scales the lack of datapoints introduces big errors in the computation of the phase coherence index.…”

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confidence: 98%

Observation of non-Gaussianity and phase synchronization in intermittent magnetic field turbulence in the solar-terrestrial environment

Miranda

Chian²,

Dasso³

et al. 2009

Proc. IAU

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Abstract. We apply two nonlinear techniques, kurtosis and phase coherence index, to analyze magnetic field measurements from SOHO MDI solar images, ACE and Cluster data in the solar wind, and ground magnetometers in Brazil. We focus on two events: a non-ICME event in February 2002 and an ICME event in January 2005. Finite degree of non-Gaussianity and phase synchronization are observed in all datasets. The nonlinear response of the Earth's geomagnetic field to an ICME event in the solar wind is discussed.

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Cited by 72 publications

References 6 publications

Cluster and ACE observations of phase synchronization in intermittent magnetic field turbulence: a comparative study of shocked and unshocked solar wind

Cluster and ACE observations of phase synchronization in intermittent magnetic field turbulence: a comparative study of shocked and unshocked solar wind

The Phase Coherence of Interstellar Density Fluctuations

Observation of non-Gaussianity and phase synchronization in intermittent magnetic field turbulence in the solar-terrestrial environment

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