Seeing the Invisible Sun: Reconstructing Far-Side Magnetograms from Helioseismology

Seeing the Invisible Sun: Reconstructing Far-Side Magnetograms from Helioseismology | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Seeing the Invisible Sun: Reconstructing Far-Side Magnetograms from Helioseismology Amr Hamada, Kiran Jain, Hanna Strecker, Charles Lindsey, David Suarez This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8223218/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 11 Mar, 2026 Read the published version in Scientific Reports → Version 1 posted 10 You are reading this latest preprint version Abstract Understanding and monitoring solar active regions is essential for operational space-weather forecasting and better solar dynamo modeling. This requires comprehensive 360$^\circ$ observations of the Sun. The front-side active regions are observed across multiple wavelengths,however, a critical gap in our knowledge remains due to the lack of direct, continuous magnetic field measurements of far-side active regions, specifically, magnetic field, polarity configurations and other parameters. We present a methodology for inferring magnetic field distributions of active regions in helioseismic maps of the far hemisphere. The crux of the analysis is the ability to realistically surmise the signs of the magnetic polarities of opposing components of a helioseismic signature. We present a method for stable, continuous polarity assignment of large-scale magnetic structures, derived from substructures that helioseismic signatures reliably resolve in strong active regions — particularly those that become space-weather hazards as solar rotation brings them into Earth’s view. Polarity boundaries are identified by analyzing the bi-modal longitudinal variance profile of the seismic signal within each region, after which Hale’s polarity rule is applied to establish east–west ordering consistent with the solar cycle. The method yields full-Sun magnetograms vital for coronal and solar-wind modeling, driving progress in heliospheric simulations and operational forecasting. Physical sciences/Astronomy and planetary science Earth and environmental sciences/Solid earth sciences Earth and environmental sciences/Space physics Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 11 Mar, 2026 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 12 Jan, 2026 Reviews received at journal 07 Jan, 2026 Reviews received at journal 14 Dec, 2025 Reviewers agreed at journal 11 Dec, 2025 Reviewers agreed at journal 11 Dec, 2025 Reviewers invited by journal 08 Dec, 2025 Editor invited by journal 02 Dec, 2025 Editor assigned by journal 29 Nov, 2025 Submission checks completed at journal 29 Nov, 2025 First submitted to journal 27 Nov, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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