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arXiv · 2610.34510

Magnetic Topological Evolution and the Predictive Role of Winding-flux-based Masked PILs in Extreme Solar Flares from AR13664 and AR13842

Prithish Halder·Sudheer K. Mishra·Abhishekh K. Srivastava·Ayumi Asai·Peter A. Dowben
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Abstract

Using vector magnetogram data from the Helioseismic Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO), we present detailed case studies of precursor activity in Active Regions (ARs) 13664 and 13842, which produced several intense flares. We examined the spatiotemporal evolution of key magnetic topological parameters, including winding, helicity, winding-flux-based masked polarity inversion lines (PILs), and PIL gradients, from the precursor to the post-flare phases. The temporal evolution of the winding flux showed a significant enhancement during the precursor phase, and this trend was consistent across the seven X-class and five M-class flares (>= M5.0). The spatial distribution of both raw and Gaussian-smoothed winding-flux enhancement is co-located with flare footpoint regions of highly twisted core fields, as indicated by the photospheric magnetic topology. The winding-flux-based masked PILs that persisted around the flare locations showed a significant increase in strength and area during the precursor activity. These masked PILs spatially coincide with regions likely hosting non-potential core magnetic fields associated with the observed flares. Furthermore, the gradient of strong PILs extracted from the ARs was positively correlated with flare-associated locations and typically increased several hours (approx. 3-5 h) before flare onset. By imposing a gradient threshold on strong PILs, we isolate magnetic regions repeatedly associated with flare initiation, providing useful constraints in regimes where current flare-forecasting models remain uncertain. Therefore, the combined analysis of the spatiotemporal evolution of different magnetic topological parameters enhances our understanding of intense solar flare forecasting and the identification of potential triggering sites, thereby contributing to improved space weather prediction frameworks.

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Prithish Halder, Sudheer K. Mishra, Abhishekh K. Srivastava, Ayumi Asai, Peter A. Dowben. 2026-10-25. Magnetic Topological Evolution and the Predictive Role of Winding-flux-based Masked PILs in Extreme Solar Flares from AR13664 and AR13842. https://arxiv.org/abs/2610.34510

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