Successfully Reproducing Solar Orbiter Polar Field Observations with a Surface Flux Transport Model
Abstract
The solar polar field plays a fundamental role in predicting solar-cycle strength and determines the large-scale structure of the heliospheric magnetic field. The High Resolution Telescope of the Polarimetric and Helioseismic Imager aboard Solar Orbiter (SO/PHI-HRT) provides unprecedented observations of the solar polar regions, as Solar Orbiter currently reaches heliographic latitudes of up to ±17∘, about 10∘ higher than those accessible from near-ecliptic observations. Using these observations to further test surface flux transport models, we present a successful simulation of the SO/PHI-HRT observations, reproducing the latitudinal profiles of the longitudinally averaged radial magnetic field in both polar regions. This result is achieved using the meridional-flow profile proposed by \citet{WangRH2026}, which also reproduces the evolution of the axial dipole strength, magnetic butterfly diagram, and high-latitude magnetic fields observed by SDO/HMI during Solar Cycle 25. We further compare simulations using this profile with simulations employing two representative meridional-flow profiles characterized by different peak latitudes. The latter fail to reproduce the observed high-latitude and polar fields. The comparison demonstrates that the meridional-flow profile strongly regulates poleward flux transport and the resulting polar-field evolution. Profiles peaking at higher latitudes produce stronger flux surges, and stronger and more concentrated polar fields. These results provide new constraints on the large-scale solar meridional flow.
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BibTeX
@misc{wang2026successfully,
title = {{Successfully Reproducing Solar Orbiter Polar Field Observations with a Surface Flux Transport Model}},
author = {Ruihui Wang and Jie Jiang and Yukun Luo and D. Calchetti and S. K. Solanki},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.32194},
eprint = {2609.32194},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.32194},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Successfully Reproducing Solar Orbiter Polar Field Observations with a Surface Flux Transport Model
AU - Ruihui Wang
AU - Jie Jiang
AU - Yukun Luo
AU - D. Calchetti
AU - S. K. Solanki
PY - 2026
DA - 2026/09/26
PB - arXiv
DO - 10.48550/arxiv.2609.32194
UR - https://arxiv.org/abs/2609.32194
AB - The solar polar field plays a fundamental role in predicting solar-cycle strength and determines the large-scale structure of the heliospheric magnetic field. The High Resolution Telescope of the Polarimetric and Helioseismic Imager aboard Solar Orbiter (SO/PHI-HRT) provides unprecedented observations of the solar polar regions, as Solar Orbiter currently reaches heliographic latitudes of up to ±17^∘, about 10^∘ higher than those accessible from near-ecliptic observations. Using these observations to further test surface flux transport models, we present a successful simulation of the SO/PHI-HRT observations, reproducing the latitudinal profiles of the longitudinally averaged radial magnetic field in both polar regions. This result is achieved using the meridional-flow profile proposed by \citet{WangRH2026}, which also reproduces the evolution of the axial dipole strength, magnetic butterfly diagram, and high-latitude magnetic fields observed by SDO/HMI during Solar Cycle 25. We further compare simulations using this profile with simulations employing two representative meridional-flow profiles characterized by different peak latitudes. The latter fail to reproduce the observed high-latitude and polar fields. The comparison demonstrates that the meridional-flow profile strongly regulates poleward flux transport and the resulting polar-field evolution. Profiles peaking at higher latitudes produce stronger flux surges, and stronger and more concentrated polar fields. These results provide new constraints on the large-scale solar meridional flow.
ER -