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Scale-dependent Polarization of Solar Wind Velocity Fluctuations at the Inertial and Kinetic Scales

Safrankova, J; Nemecek, Z; Nemec, F; Verscharen, D; Chen, CHK; Durovcova, T; Riazantseva, MO; (2019) Scale-dependent Polarization of Solar Wind Velocity Fluctuations at the Inertial and Kinetic Scales. Astrophysical Journal , 870 (1) , Article 40. 10.3847/1538-4357/aaf239. Green open access

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Abstract

We study the polarization properties of the velocity fluctuations in solar wind turbulence using high-resolution data from the Spektr-R spacecraft. The ratio of perpendicular to parallel velocity fluctuations in the inertial range is smaller than the equivalent ratio for magnetic fluctuations, but gradually increases throughout this range. In the kinetic range, there is a large decrease in the ratio, similar to the magnetic fluctuations. We compare the measurements to numerical solutions for a combination of kinetic Alfvén waves and slow waves, finding that both the slow increase and sharp decrease in the ratio are consistent with a majority population of Alfvén waves and minority population of slow waves in critical balance. Furthermore, the beta-dependence of this scale-dependent ratio can be successfully captured in the model when incorporating a beta-dependent Alfvén to slow wave ratio similar to that observed in the solar wind.

Type: Article
Title: Scale-dependent Polarization of Solar Wind Velocity Fluctuations at the Inertial and Kinetic Scales
Open access status: An open access version is available from UCL Discovery
DOI: 10.3847/1538-4357/aaf239
Publisher version: https://doi.org/10.3847/1538-4357/aaf239
Language: English
Additional information: This is the published version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Solar wind, turbulence, velocity fluctuations
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/10061804
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