Review article: Wave analysis methods for space plasma experiment

Narita, Yasuhito

doi:10.5194/npg-24-203-2017

Cited by 13 publications

(14 citation statements)

References 69 publications

(60 reference statements)

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“…Recently, Bourouaine & Perez (2018), which we call BP18 hereafter, have investigated the validity of TH near r ≃ 10R ⊙ using numerical simulations of Reflection-driven Magnetohydrodynamic (MHD) turbulence. The authors found that the Eulerian spacetime structure of the turbulence allows for the interpretation of time signals even when TH is not applicable, largely consistent with similar works (Matthaeus et al 2010;Servidio et al 2011;Narita et al 2013;Weygand et al 2013;Klein et al 2014Klein et al , 2015Matthaeus et al 2016;Narita 2017), but with a number of important differences. For instance, BP18 find that the Eulerian decorrelation in simula-1 email: sbourouaine@fit.edu tions is consistent with spectral broadening associated with pure hydrodynamic sweeping by the large-scale eddies, combined with a Doppler shift associated with Alfvénic propagation along the background magnetic field.…”

Section: Introductionsupporting

confidence: 82%

On the Interpretation of Parker Solar Probe Turbulent Signals

Bourouaine¹,

Perez²

2019

ApJL

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In this letter we propose a practical methodology to interpret future Parker Solar Probe (PSP) turbulent time signals even when Taylor's hypothesis is not valid. By extending Kraichnan's sweeping model used in hydrodynamics we derive the Eulerian spacetime correlation function in magnetohydrodynamics (MHD) turbulence. It is shown that in MHD, the temporal decorrelation of small-scale fluctuations arises from a combination of hydrodynamic sweeping induced by large-scale fluid velocity δ u 0 and by the Alfvénic propagation along the local magnetic field. The resulting temporal part of the space-time correlation function is used to determine the wavenumber range ∆k ⊥ = [k min , k max ] of the turbulent fluctuations that contribute to the power of a given frequency ω of the time signal measured in the spacecraft frame. Our analysis also shows that the shape of frequency power spectrum P sc (ω) of the time signal will follow the same power-law of the reduced power spectrum E(k ⊥ ) ∼ k −α ⊥ in the plasma frame, where α is the spectral index. The proposed framework for the analysis of PSP time signals entirely relies on two simple dimensionless parameters that can be empirically obtained from PSP measurements, namely, ε = δ u 0 / √ 2V ⊥ (where V ⊥ is the perpendicular velocity of PSP seen in the plasma frame) and the spectral index α.

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Section: Introductionsupporting

confidence: 82%

On the Interpretation of Parker Solar Probe Turbulent Signals

Bourouaine¹,

Perez²

2019

ApJL

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“…Because of the ambiguity of the MVA to the sign, the range of values for the angle spans over [0, 180 • ]. As mentioned by, among others, Narita (2017), the minimum variance analysis fails for linearly polarized waves because the polarization plane is not uniquely determined. Therefore, all waves with an ellipticity above 0.9 are disregarded for the analysis of the minimum variance direction.…”

Section: Minimum Variance Directionmentioning

confidence: 99%

Steepening of magnetosonic waves in the inner coma of comet 67P/Churyumov–Gerasimenko

et al. 2021

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Abstract. We present a statistical survey of large-amplitude, asymmetric plasma and magnetic field enhancements detected outside the diamagnetic cavity at comet 67P/Churyumov–Gerasimenko from December 2014 to June 2016. Based on the concurrent observations of plasma and magnetic field enhancements, we interpret them to be magnetosonic waves. The aim is to provide a general overview of these waves' properties over the mission duration. As the first mission of its kind, the ESA Rosetta mission was able to study the plasma properties of the inner coma for a prolonged time and during different stages of activity. This enables us to study the temporal evolution of these waves and their characteristics. In total, we identified ∼ 70 000 steepened waves in the magnetic field data by means of machine learning. We observe that the occurrence of these steepened waves is linked to the activity of the comet, where steepened waves are primarily observed at high outgassing rates. No clear indications of a relationship between the occurrence rate and solar wind conditions were found. The waves are found to propagate predominantly perpendicular to the background magnetic field, which indicates their compressional nature. Characteristics like amplitude, skewness, and width of the waves were extracted by fitting a skew normal distribution to the magnetic field magnitude of individual steepened waves. With increasing mass loading, the average amplitude of the waves decreases, while the skewness increases. Using a modified 1D magnetohydrodynamic (MHD) model, we investigated if the waves can be described by the combination of nonlinear and dissipative effects. By combining the model with observations of amplitude, width and skewness, we obtain an estimate of the effective plasma diffusivity in the comet–solar wind interaction region and compare it with suitable reference values as a consistency check. At 67P/Churyumov–Gerasimenko, these steepened waves are of particular importance as they dominate the innermost interaction region for intermediate to high activity.

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“…The degree of polarization, the wave normal angle, and the ellipticity of the waves in both events are presented in panels (d)-(g) and (k)-(n). The degree of polarization and the ellipticity are close to 1 (red), indicating that the identified waves are purely right-handed circular whistler waves (Huang et al, 2016;Narita, 2017). The direction of the wave vector k is determined by the minimum variance analysis of B (Sonnerup & Scheible, 1998) with a time window 0.2 s. The wave normal angle, defined as the angle between the propagation direction (k) and the ambient magnetic field, varies between 0 • and 50 • in both events.…”

Section: Whistler Mode Wavesmentioning

confidence: 91%

“…Whistler mode waves have been observed prior to and during the magnetotail reconnection using Cluster data (Wei et al, 2007). At the dayside magnetopause reconnection, whistler mode waves have been reported in the separatrix region from Cluster (Graham et al, 2016) and recent Magnetospheric Multiscale Mission (MMS) observations (Le Contel, Retinò, et al, 2016;Wilder et al, 2016, 2017, Yoo et al, 2018. In the magnetotail, Cluster observations show that whistler waves occur near the separatrix region and the magnetic pileup region of downstream flows (Huang et al, 2016).…”

Section: Introductionmentioning

confidence: 98%

Whistler Waves Driven by Field‐Aligned Streaming Electrons in the Near‐Earth Magnetotail Reconnection

Ren

Dai

et al. 2019

Geophysical Research Letters

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We analyze Magnetospheric Multiscale Mission observations of whistler waves and associated electron field‐aligned crescent distribution in the vicinity of the magnetotail near‐Earth X‐line. The whistler waves propagate outward from the X‐line in the neutral sheet. The associated field‐aligned streaming electrons exhibit a crescent‐like shape, with an inverse slope (df/d|v|||>0) at 1–5 keV. The parallel phase velocity of the waves is in the range (1–5 keV) of the inverse slope of the field‐aligned crescents in the velocity space. We demonstrate that the observed whistler waves are driven by the electron field‐aligned crescents through Landau resonance. The cyclotron resonance is at the high‐energy tail with negligible free energy of pitch angle anisotropy in these events.

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Review article: Wave analysis methods for space plasma experiment

Cited by 13 publications

References 69 publications

On the Interpretation of Parker Solar Probe Turbulent Signals

On the Interpretation of Parker Solar Probe Turbulent Signals

Steepening of magnetosonic waves in the inner coma of comet 67P/Churyumov–Gerasimenko

Whistler Waves Driven by Field‐Aligned Streaming Electrons in the Near‐Earth Magnetotail Reconnection

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