Sioulas, Nikos;
Velli, Marco;
Huang, Zesen;
Shi, Chen;
Bowen, Trevor A;
Chandran, BDG;
Liodis, Ioannis;
... Bonnell, John W; + view all
(2023)
On the Evolution of the Anisotropic Scaling of Magnetohydrodynamic Turbulence in the Inner Heliosphere.
The Astrophysical Journal
, 951
(2)
, Article 141. 10.3847/1538-4357/acc658.
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Abstract
We analyze a merged Parker Solar Probe (PSP) and Solar Orbiter (SO) data set covering heliocentric distances 13 R⊙ ≲ R ≲ 220 R⊙ to investigate the radial evolution of power and spectral index anisotropy in the wavevector space of solar wind turbulence. Our results show that anisotropic signatures of turbulence display a distinct radial evolution when fast, Vsw ≥ 400 km s−1, and slow, Vsw ≤ 400 km s−1, wind streams are considered. The anisotropic properties of slow wind in Earth orbit are consistent with a "critically balanced" cascade, but both spectral index anisotropy and power anisotropy diminish with decreasing heliographic distance. Fast streams are observed to roughly retain their near-Sun anisotropic properties, with the observed spectral index and power anisotropies being more consistent with a "dynamically aligned" type of cascade, though the lack of extended fast wind intervals makes it difficult to accurately measure the anisotropic scaling. A high-resolution analysis during the first perihelion of PSP confirms the presence of two subranges within the inertial range, which may be associated with the transition from weak to strong turbulence. The transition occurs at κdi ≈ 6 × 10−2 and signifies a shift from −5/3 to −2 and from −3/2 to −1.57 scaling in parallel and perpendicular spectra, respectively. Our results provide strong observational constraints for anisotropic theories of MHD turbulence in the solar wind.
Type: | Article |
---|---|
Title: | On the Evolution of the Anisotropic Scaling of Magnetohydrodynamic Turbulence in the Inner Heliosphere |
Open access status: | An open access version is available from UCL Discovery |
DOI: | 10.3847/1538-4357/acc658 |
Publisher version: | https://doi.org/10.3847/1538-4357/acc658 |
Language: | English |
Additional information: | Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence (https://creativecommons.org/licenses/by/4.0/). Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. |
UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
URI: | https://discovery.ucl.ac.uk/id/eprint/10173386 |
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