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Hemispheric injection of magnetic helicity by surface flux transport

Hawkes, G.; Yeates, A.R.

Hemispheric injection of magnetic helicity by surface flux transport Thumbnail


Authors

G. Hawkes



Abstract

Aims. We estimate the injection of relative magnetic helicity into the solar atmosphere by surface flux transport over 27 solar cycles (1700–2009). Methods. We determine the radial magnetic field evolution using two separate surface flux transport models: one driven by magnetogram inputs and another by statistical active region insertion guided by the sunspot number record. The injection of relative magnetic helicity is then computed from this radial magnetic field together with the known electric field in the flux transport models. Results. Neglecting flux emergence, solar rotation is the dominant contributor to the helicity injection. At high latitudes, the injection is always negative/positive in the northern/southern hemisphere, while at low latitudes the injection tends to have the opposite sign when integrated over the full solar cycle. The overall helicity injection in a given solar cycle depends on the balance between these two contributions. This net injected helicity correlates well with the end-of-cycle axial dipole moment.

Citation

Hawkes, G., & Yeates, A. (2019). Hemispheric injection of magnetic helicity by surface flux transport. Astronomy & Astrophysics, 631, Article A138. https://doi.org/10.1051/0004-6361/201936475

Journal Article Type Article
Acceptance Date Oct 2, 2019
Online Publication Date Nov 7, 2019
Publication Date Nov 30, 2019
Deposit Date Nov 8, 2019
Publicly Available Date Mar 29, 2024
Journal Astronomy and astrophysics.
Print ISSN 0004-6361
Electronic ISSN 1432-0746
Publisher EDP Sciences
Peer Reviewed Peer Reviewed
Volume 631
Article Number A138
DOI https://doi.org/10.1051/0004-6361/201936475

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Copyright Statement
Hawkes, G. & Yeates, A. R. (2019). Hemispheric injection of magnetic helicity by surface flux transport. Astronomy & Astrophysics 631: A138, reproduced with permission, © ESO.




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