Systematic averaging interval effects on solar wind statistics

Isaacs, Joshua; Tessein, Jeffrey A.; Matthaeus, W. H.

doi:10.1002/2014ja020661

Cited by 51 publications

(45 citation statements)

References 44 publications

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“…In this study we used the correlation time computed in Parashar et al (2019). However there are there are few subtleties associated with this calculation, and Smith et al (2001); Isaacs et al (2015); Krishna Jagarlamudi et al (2019); Bandyopadhyay et al (2019) offer more insights and discussion on this topic along with potential issues in such determination. We also carried out the analysis for various different averaging times (from 1 to 12 hours) and it was observed to have minimal affect on the outcome.…”

Section: Data Selection and Methodologymentioning

confidence: 99%

Observations of Heating along Intermittent Structures in the Inner Heliosphere from PSP Data

Qudsi

Maruca

Matthaeus

et al. 2020

ApJS

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The solar wind proton temperature at 1-au has been found to be correlated with small-scale intermittent magnetic structures, i.e., regions with enhanced temperature are associated with coherent structures such as current sheets. Using Parker Solar Probe data from the first encounter, we study this association using measurements of radial proton temperature, employing the Partial Variance of Increments (PVI) technique to identify intermittent magnetic structures. We observe that the probability density functions of high-PVI events have higher median temperatures than those with lower PVI, The regions in space where PVI peaks were also locations that had enhanced temperatures when compared with similar regions suggesting a heating mechanism in the young solar wind that is associated with intermittency developed by a nonlinear turbulent cascade.n the immediate vicinity.

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Section: Data Selection and Methodologymentioning

confidence: 99%

Observations of Heating along Intermittent Structures in the Inner Heliosphere from PSP Data

Qudsi

Maruca

Matthaeus

et al. 2020

ApJS

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“…where δB(t) = B(t) − B , also for 1-day intervals 9 . The correlation scale, τ c , can be obtained from C(τ ) in various ways (e.g., Ruiz et al 2014;Isaacs et al 2015); here it was taken as the point where C decreases such that C(τ c ) = e −1 . The radial variation of the two outer scale estimates, τ b and τ c , is shown in Figure 9(a-b).…”

Section: Turbulence Outer Scalementioning

confidence: 99%

“…While the solar wind correlation time has been shown to depend on the length of the interval used to calculate it(Matthaeus & Goldstein 1982;Isaacs et al 2015;Krishna Jagarlamudi et al 2019), here we choose 1-day intervals as a reasonable compromise, and are more interested in its radial dependence than absolute value.…”

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confidence: 99%

The Evolution and Role of Solar Wind Turbulence in the Inner Heliosphere

Chen¹

2020

Preprint

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The first two orbits of the Parker Solar Probe (PSP) spacecraft have enabled the first in situ measurements of the solar wind down to a heliocentric distance of 0.17 au (or 36 R ⊙ ). Here, we present an analysis of this data to study solar wind turbulence at 0.17 au and its evolution out to 1 au. While many features remain similar, key differences at 0.17 au include: increased turbulence energy levels by more than an order of magnitude, a magnetic field spectral index of −3/2 matching that of the velocity and both Elsasser fields, a lower magnetic compressibility consistent with a smaller slow-mode kinetic energy fraction, and a much smaller outer scale that has had time for substantial nonlinear processing. There is also an overall increase in the dominance of outward-propagating Alfvénic fluctuations compared to inward-propagating ones, and the radial variation of the inward component is consistent with its generation by reflection from the large-scale gradient in Alfvén speed. The energy flux in this turbulence at 0.17 au was found to be ∼10% of that in the bulk solar wind kinetic energy, becoming ∼40% when extrapolated to the Alfvén point, and both the fraction and rate of increase of this flux towards the Sun is consistent with turbulence-driven models in which the solar wind is powered by this flux.

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“…At 150 Gm, typical values of the turbulent velocity Z(150 Gm) and correlation length L(150 Gm) are 25 km s −1 and 1 Gm, respectively (Ruiz et al 2014;Isaacs et al 2015). Both of these quantities are approximately log-normally distributed, soextreme outliers are to be expected.…”

Section: Fading Of the Striaementioning

confidence: 99%

Fading Coronal Structure and the Onset of Turbulence in the Young Solar Wind

DeForest

Matthaeus

Viall

et al. 2016

ApJ

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Above the top of the solar corona, the young, slow solar wind transitions from low-β, magnetically structured flow dominated by radial structuresto high-β, less structured flow dominated by hydrodynamics. This transition, long inferred via theory, is readily apparent in the sky region close to 10°from the Sunin processed, backgroundsubtracted solar wind images. We present image sequences collected by the inner Heliospheric Imager instrument on board the Solar-Terrestrial Relations Observatory (STEREO/HI1) in 2008 December, covering apparent distances from approximately 4°to24°from the center of the Sun and spanning this transition in thelarge-scale morphology of the wind. We describe the observation and novel techniques to extract evolving image structure from the images, and we use those data and techniques to present and quantify the clear textural shift in the apparent structure of the corona and solar wind in this altitude range. We demonstrate that the change in apparent texture is due both to anomalous fading of the radial striae that characterize the coronaand to anomalous relative brightening of locally dense puffs of solar wind that we term "flocculae."Weshow that these phenomena are inconsistent with smooth radial flow, but consistent with theonset of hydrodynamic or magnetohydrodynamic instabilities leading to a turbulent cascade in the young solar wind.

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Systematic averaging interval effects on solar wind statistics

Cited by 51 publications

References 44 publications

Observations of Heating along Intermittent Structures in the Inner Heliosphere from PSP Data

Observations of Heating along Intermittent Structures in the Inner Heliosphere from PSP Data

The Evolution and Role of Solar Wind Turbulence in the Inner Heliosphere

Fading Coronal Structure and the Onset of Turbulence in the Young Solar Wind

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