Evolution of Magnetic Field Fluctuations and Their Spectral Properties within the Heliosphere: Statistical Approach

Šafránková, Jana; Němeček, Zdenek; Němec, F.; Verscharen, Daniel; Horbury, T. S.; Bale, S. D.; Přech, Lubomír

doi:10.3847/2041-8213/acc531

Cited by 8 publications

(3 citation statements)

References 42 publications

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“…In this paper a transition in the magnetic field spectral index has been shown from −5/3 far from the Sun to −3/2 close to the Sun, with the transition occurring at around 50 R e . This is in agreement with previous observations (Chen et al 2020;Shi et al 2021;Šafránková et al 2023;Sioulas et al 2023), although Lotz et al (2023), using data from the fifth orbit of PSP, found only a weak trend with distance, with the spectrum possibly steeper closer to the Sun. However, this work appears to use a considerably higher frequency range to determine the index than the other work referenced.…”

Section: Discussionsupporting

confidence: 93%

Properties Underlying the Variation of the Magnetic Field Spectral Index in the Inner Solar Wind

McIntyre,

Chen,

Larosa

2023

ApJ

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Using data from orbits 1−11 of the Parker Solar Probe mission, the magnetic field spectral index was measured across a range of heliocentric distances. The previously observed transition between a value of −5/3 far from the Sun and a value of −3/2 close to the Sun was recovered, with the transition occurring at around 50 R ⊙ and the index saturating at −3/2 as the Sun is approached. A statistical analysis was performed to separate the variation of the index on distance from its dependence on other parameters of the solar wind that are plausibly responsible for the transition, including the cross helicity, residual energy, turbulence age, and magnitude of magnetic fluctuations. Of all parameters considered, the cross helicity was found to be by far the strongest candidate for the underlying variable responsible. The velocity spectral index was also measured and found to be consistent with −3/2 over the range of values of cross helicity measured. Possible explanations for the behavior of the indices are discussed, including the theorized different behavior of imbalanced, compared to balanced, turbulence.

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Section: Discussionsupporting

confidence: 93%

Properties Underlying the Variation of the Magnetic Field Spectral Index in the Inner Solar Wind

McIntyre,

Chen,

Larosa

2023

ApJ

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“…The regime where kλ i = 1 and kρ i = 1 (k is the wavenumber of the magnetic field fluctuations in the plasma frame) is called the inertial range. The power spectrum of the magnetic field fluctuations in this range evolves with the distance from the Sun from an Iroshnikov-Kraichnan power law with the exponent of −3/2 toward the Kolmogorov-like exponent of −5/3 observed at 1 au (Chen et al 2020;Zhao et al 2022b;Šafránková et al 2023;and references therein).…”

Section: Introductionmentioning

confidence: 85%

Change of Spectral Properties of Magnetic Field Fluctuations across Different Types of Interplanetary Shocks

Park,

Pitňa,

Šafránková

et al. 2023

ApJL

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The interaction between interplanetary (IP) shocks and the solar wind has been studied in the past for the understanding of energy dissipation mechanisms within collisionless plasmas. Compared to the study of fast shocks, other types of IP shocks, including slow mode shocks (i.e., fast forward, fast reverse, slow forward, and slow reverse shocks) remained largely unnoticed. We analyze magnetic field fluctuations observed by the Wind spacecraft from 1995 to 2021 upstream and downstream of the IP shocks using a continuous wavelet transform. The evolution of spectral indices in the ion inertial and transition ranges and the changes in distributions of characteristic ion length scales with respect to the spectral break and proton beta are presented. We found that spectral indices in both inertial and transition ranges and the characteristic length scale distributions are statistically conserved across three types of IP shocks, suggesting that mechanisms associated with the energy dissipation are unaffected by the shocks. The results obtained for the transition range of fast reverse shocks show a larger difference between upstream and downstream plasmas and this will be further studied.

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“…A statistical study of the evolution of the solar wind will help us understand the origin of the solar wind and the physical mechanisms involved. Especially, considering the near-Sun solar wind may carry more coronal source characteristics, the accurate radial evolution of the near-Sun solar wind may be not consistent with the prediction of previous models at larger heliocentric distance (Halekas et al 2020;Abraham et al 2022;Mostafavi et al 2022;Šafránková et al 2023;Liu et al 2023). Therefore, in this Letter, we aim to present the radial evolution of solar wind parameters below 0.3 au by analyzing PSP observations from Encounters 1-15 statistically.…”

Section: Introductionmentioning

confidence: 97%

Radial Evolution of the Near-Sun Solar Wind: Parker Solar Probe Observations

Liu,

Jia,

Liu

2024

ApJL

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A statistical study of the radial evolution of the solar wind within 0.3 au is shown in this Letter based on Parker Solar Probe observations. We show the radial distribution of the main solar wind parameters, including the solar wind speed V sw, magnetic field ∣B∣, the number density of electrons N e , protons N p , and α particles N α , and the temperature of protons T p and α particles T α . The power-law fitting results of these parameters in the near-Sun solar wind are compared with previous radial models. We also show the radial distribution of the angle between the magnetic field B , solar wind V sw, and radial vector R . In the solar wind within 0.3 au, θ BV sw , and θ BR mainly concentrate around 135°, and θ RV sw almost concentrates in the region less than 20°. Furthermore, we also present the radial distribution of the relative values between the solar wind parameters, including the electric neutrality estimation ((2 × N α + N p )/N e ≃ 1 within 0.2 au), relative number density ratio (N α /N p ≃ 0.02 in slow solar wind and N α /N p ≃ 0.04 in faster solar wind), relative temperature ratio (T α /T p decreases with the increase of heliocentric distance and its decay rate is larger in faster solar wind), and differential speed (both V α − V p and (V α − V p )/V A are larger in the faster solar wind and decrease as heliocentric distance increases).

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Evolution of Magnetic Field Fluctuations and Their Spectral Properties within the Heliosphere: Statistical Approach

Cited by 8 publications

References 42 publications

Properties Underlying the Variation of the Magnetic Field Spectral Index in the Inner Solar Wind

Properties Underlying the Variation of the Magnetic Field Spectral Index in the Inner Solar Wind

Change of Spectral Properties of Magnetic Field Fluctuations across Different Types of Interplanetary Shocks

Radial Evolution of the Near-Sun Solar Wind: Parker Solar Probe Observations

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