The Open Flux Problem
By Jon A. Linker, R. Caplan, C. Downs, Pete Riley, Z. Mikić, Roberto Lionello, Carl J. Henney, C. Arge, Yi A. Liu, M. DeRosa and 2 more. 2017
179 citations recorded by the source corpus.
The heliospheric magnetic field is of pivotal importance in solar and space physics. The field is rooted in the Sun’s photosphere, where it has been observed for many years. Global maps of the solar magnetic field based on full-disk magnetograms are commonly used as boundary conditions for coronal and solar wind models. Two primary observational constraints on the models are (1) the open field regions in the model should approximately correspond to coronal holes (CHs) observed in emission and (2) the magnitude of the open magnetic flux in the model should match that inferred from in situ spacecraft measurements. In this study, we calculate both magnetohydrodynamic and potential field source surface solutions using 14 different magnetic maps produced from five different types of observatory magnetograms, for the time period surrounding 2010 July. We have found that for all of the model/map combinations, models that have CH areas close to observations underestimate the interplanetary magnetic flux, or, conversely, for models to match the interplanetary flux, the modeled open field regions are larger than CHs observed in EUV emission. In an alternative approach, we estimate the open magnetic flux entirely from solar observations by combining automatically detected CHs for Carrington rotation 2098 with observatory synoptic magnetic maps. This approach also underestimates the interplanetary magnetic flux. Our results imply that either typical observatory maps underestimate the Sun’s magnetic flux, or a significant portion of the open magnetic flux is not rooted in regions that are obviously dark in EUV and X-ray emission.
Subfields: Astronomy and Astrophysics, Molecular Biology
View Paper: https://www.semanticscholar.org/paper/5884ec6c1f1c6e32567efc42b010a59bce36bbb7
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Citations in the corpus
- EUHFORIA: European heliospheric forecasting information asset (2018, background): “…magnetic field model but rather from the computed wind speed in order to avoid the so-called open flux problem, i.e., the issue that the magnetic field strength in interplanetary space is often underestimated when inferred from coronal models, see e.g., Linker et al. (2017) and references therein.”
- Space weather: the solar perspective (2021, background): “Still, an open discussion is the discrepancy between estimates of open solar magnetic flux from remote photospheric and in-situ spacecraft observations that may differ by as much as a factor of two (e.g., Arden et al., 2014; Linker et al., 2017; Wallace et al., 2019).”