Characteristic Scales of Magnetic Switchback Patches Near the Sun and Their Possible Association With Solar Supergranulation and Granulation - Archive ouverte HAL Access content directly
Journal Articles The Astrophysical Journal Year : 2021

Characteristic Scales of Magnetic Switchback Patches Near the Sun and Their Possible Association With Solar Supergranulation and Granulation

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Naïs Fargette
Benoit Lavraud
Alexis Rouillard
Victor Réville
Clara Froment
Jasper Halekas
Tai Phan
David Malaspina
Stuart Bale
Justin Kasper
Philippe Louarn
Anthony Case
Kelly Korreck
Davin Larson
Marc Pulupa
Michael Stevens
Phyllis Whittlesey
Matthieu Berthomier

Abstract

Parker Solar Probe (PSP) data recorded within a heliocentric radial distance of 0.3 au have revealed a magnetic field dominated by Alfvénic structures that undergo large local variations or even reversals of the radial magnetic field. They are called magnetic switchbacks, they are consistent with folds in magnetic field lines within a same magnetic sector and are associated with velocity spikes during an otherwise calmer background. They are thought to originate either in the low solar atmosphere through magnetic reconnection processes or result from the evolution of turbulence or velocity shears in the expanding solar wind. In this work, we investigate the temporal and spatial characteristic scales of magnetic switchback patches. We define switchbacks as a deviation from the nominal Parker spiral direction and detect them automatically for PSP encounters 1, 2, 4, and 5. We focus in particular on a 5.1 day interval dominated by switchbacks during E5. We perform a wavelet transform of the solid angle between the magnetic field and the Parker spiral and find periodic spatial modulations with two distinct wavelengths, respectively consistent with solar granulation and supergranulation scales. In addition we find that switchback occurrence and spectral properties seem to depend on the source region of the solar wind rather than on the radial distance of PSP. These results suggest that switchbacks are formed in the low corona and modulated by the solar surface convection pattern.

Dates and versions

insu-03388537 , version 1 (20-10-2021)

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Naïs Fargette, Benoit Lavraud, Alexis Rouillard, Victor Réville, Thierry Dudok de Wit, et al.. Characteristic Scales of Magnetic Switchback Patches Near the Sun and Their Possible Association With Solar Supergranulation and Granulation. The Astrophysical Journal, 2021, 919 (2), pp.96. ⟨10.3847/1538-4357/ac1112⟩. ⟨insu-03388537⟩
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