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Active Region Contributions to the Solar Wind over Multiple Solar Cycles

Stansby, D; Green, LM; van Driel-Gesztelyi, L; Horbury, TS; (2021) Active Region Contributions to the Solar Wind over Multiple Solar Cycles. Solar Physics , 296 , Article 116. 10.1007/s11207-021-01861-x. Green open access

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Abstract

Both coronal holes and active regions are source regions of the solar wind. The distribution of these coronal structures across both space and time is well known, but it is unclear how much each source contributes to the solar wind. In this study we use photospheric magnetic field maps observed over the past four solar cycles to estimate what fraction of magnetic open solar flux is rooted in active regions, a proxy for the fraction of all solar wind originating in active regions. We find that the fractional contribution of active regions to the solar wind varies between 30% to 80% at any one time during solar maximum and is negligible at solar minimum, showing a strong correlation with sunspot number. While active regions are typically confined to latitudes ±30∘ in the corona, the solar wind they produce can reach latitudes up to ±60∘. Their fractional contribution to the solar wind also correlates with coronal mass ejection rate, and is highly variable, changing by ±20% on monthly timescales within individual solar maxima. We speculate that these variations could be driven by coronal mass ejections causing reconfigurations of the coronal magnetic field on sub-monthly timescales.

Type: Article
Title: Active Region Contributions to the Solar Wind over Multiple Solar Cycles
Open access status: An open access version is available from UCL Discovery
DOI: 10.1007/s11207-021-01861-x
Publisher version: https://doi.org/10.1007/s11207-021-01861-x
Language: English
Additional information: This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Keywords: Science & Technology, Physical Sciences, Astronomy & Astrophysics, Solar cycle, Solar wind, Active regions, Coronal holes, CORONAL MAGNETIC-FIELD, IN-SITU PROPERTIES, INTERCHANGE RECONNECTION, EVOLUTION, HOLES, FLUX, TOPOLOGY, ACE
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10133200
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