@article{Horbury:2023:10.1063/5.0123250,
author = {Horbury, T and Bale, S and mcmanus, M and Larson, D and Kasper, J and Laker, R and Matteini, L and Raouafi, N and Velli, M and Woodham, L and Woolley, T and Fedorov, A and Louarn, P and Kieokaew, R and Durovcova, T and Chandran, B and Owen, C},
doi = {10.1063/5.0123250},
journal = {Physics of Plasmas},
title = {Switchbacks, microstreams and broadband turbulence in the solar wind},
url = {http://dx.doi.org/10.1063/5.0123250},
volume = {30},
year = {2023}
}

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TY  - JOUR
AB  - Switchbacks are a striking phenomenon in near-Sun coronal hole flows, but their origins, evolution, and relation to the broadband fluctuations seen farther from the Sun are unclear. We use the near-radial lineup of Solar Orbiter and Parker Solar Probe during September 2020 when both spacecraft were in wind from the Sun's Southern polar coronal hole to investigate if switchback variability is related to large scale properties near 1 au. Using the measured solar wind speed, we map measurements from both spacecraft to the source surface and consider variations with source Carrington longitude. The patch modulation of switchback amplitudes at Parker at 20 solar radii was associated with speed variations similar to microstreams and corresponds to solar longitudinal scales of around 5°–10°. Near 1 au, this speed variation was absent, probably due to interactions between plasma at different speeds during their propagation. The alpha particle fraction, which has recently been shown to have spatial variability correlated with patches at 20 solar radii, varied on a similar scale at 1 au. The switchback modulation scale of 5°–10°, corresponding to a temporal scale of several hours at Orbiter, was present as a variation in the average deflection of the field from the Parker spiral. While limited to only one stream, these results suggest that in coronal hole flows, switchback patches are related to microstreams, perhaps associated with supergranular boundaries or plumes. Patches of switchbacks appear to evolve into large scale fluctuations, which might be one driver of the ubiquitous turbulent fluctuations in the solar wind.
AU  - Horbury,T
AU  - Bale,S
AU  - mcmanus,M
AU  - Larson,D
AU  - Kasper,J
AU  - Laker,R
AU  - Matteini,L
AU  - Raouafi,N
AU  - Velli,M
AU  - Woodham,L
AU  - Woolley,T
AU  - Fedorov,A
AU  - Louarn,P
AU  - Kieokaew,R
AU  - Durovcova,T
AU  - Chandran,B
AU  - Owen,C
DO  - 10.1063/5.0123250
PY  - 2023///
SN  - 1070-664X
TI  - Switchbacks, microstreams and broadband turbulence in the solar wind
T2  - Physics of Plasmas
UR  - http://dx.doi.org/10.1063/5.0123250
UR  - http://hdl.handle.net/10044/1/102691
VL  - 30
ER  - 

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