A nonpotential model for the Sun's open magnetic flux

Yeates, A.R.; Mackay, D.H.; van Ballegooijen, A.A.; Constable, J.A.

doi:10.1029/2010ja015611

A nonpotential model for the Sun's open magnetic flux

Yeates, A.R.; Mackay, D.H.; van Ballegooijen, A.A.; Constable, J.A.

Authors

Professor Anthony Yeates anthony.yeates@durham.ac.uk
Professor

D.H. Mackay

A.A. van Ballegooijen

J.A. Constable

Abstract

[1] Measurements of the interplanetary magnetic field (IMF) over several solar cycles do not agree with computed values of open magnetic flux from potential field extrapolations. The discrepancy becomes greater around solar maximum in each cycle when the IMF can be twice as strong as predicted by the potential field model. Here we demonstrate that this discrepancy may be resolved by allowing for electric currents in the low corona (below 2.5R⊙). We present a quasi-static numerical model of the large-scale coronal magnetic evolution, which systematically produces these currents through flux emergence and shearing by surface motions. The open flux is increased by 75%–85% at solar maximum, but only 25% at solar minimum, bringing it in line with estimates from IMF measurements. The additional open flux in the nonpotential model arises through inflation of the magnetic field by electric currents, with superimposed fluctuations due to coronal mass ejections. The latter are modeled by the self-consistent ejection of twisted magnetic flux ropes.

Citation

Yeates, A., Mackay, D., van Ballegooijen, A., & Constable, J. (2010). A nonpotential model for the Sun's open magnetic flux. Journal of Geophysical Research: Space Physics, 115(A9), https://doi.org/10.1029/2010ja015611

Journal Article Type	Article
Acceptance Date	Jun 23, 2010
Publication Date	Sep 29, 2010
Deposit Date	Oct 17, 2011
Publicly Available Date	Apr 29, 2015
Journal	Journal of Geophysical Research: Space Physics
Print ISSN	2169-9402
Publisher	American Geophysical Union
Peer Reviewed	Peer Reviewed
Volume	115
Issue	A9
DOI	https://doi.org/10.1029/2010ja015611
Keywords	Open flux, Solar magnetic field, Solar activity cycle, Interplanetary magnetic field, Electric currents.

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Copyright Statement
A. R. Yeates, D. H. Mackay, A. A. van Ballegooijen, J. A. Constable, (2010), A nonpotential model for the Sun's open magnetic flux, Journal of geophysical research: space physics, 115, A09112, 10.1029/2010JA015611 (DOI). To view the published open abstract, go to http://dx.doi.org and enter the DOI.