Deciphering the pre-solar-storm features of the 2017 September storm from global and local dynamics

Raphaldini, B., Dikpati, M., Norton, A. A., Teruya, A. S. W., McIntosh, S. W., Prior, C. B. and MacTaggart, D. (2023) Deciphering the pre-solar-storm features of the 2017 September storm from global and local dynamics. Astrophysical Journal, 958, 175. (doi: 10.3847/1538-4357/acfef0)

Abstract

We investigate whether global toroid patterns and the local magnetic field topology of solar active region (AR) 12673 together can hindcast the occurrence of the biggest X-flares of solar cycle (SC)-24. Magnetic toroid patterns (narrow latitude belts warped in longitude, in which ARs are tightly bound) derived from the surface distributions of ARs, prior and during AR 12673 emergence, reveal that the portions of the south toroid containing AR 12673 was not tipped away from its north-toroid counterpart at that longitude, unlike the 2003 Halloween storms scenario. During the minimum phase there were too few emergences to determine multimode longitudinal toroid patterns. A new emergence within AR 12673 produced a complex nonpotential structure, which led to the rapid buildup of helicity and winding that triggered the biggest X-flare of SC-24, suggesting that this minimum-phase storm can be anticipated several hours before its occurrence. However, global patterns and local dynamics for a peak-phase storm, such as that from AR 11263, behaved like the 2003 Halloween storms, producing the third biggest X-flare of SC-24. AR 11263 was present at the longitude where the north and south toroids tipped away from each other. While global toroid patterns indicate that prestorm features can be forecast with a lead time of a few months, their application to observational data can be complicated by complex interactions with turbulent flows. Complex nonpotential field structure development hours before the storm are necessary for short-term prediction. We infer that minimum-phase storms cannot be forecast accurately more than a few hours ahead, while flare-prone ARs in the peak phase may be anticipated much earlier, possibly months ahead from global toroid patterns.

• Item Type: Articles
• Additional Information: This work is supported by the National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation under cooperative agreement 1852977. We acknowledge support from several NASA grants, namely MD and BR acknowledge NASA-LWS award 80NSSC20K0355, NASA-HSR award 80NSSC21K1676. MD also acknowledges COFFIES Phase II NASA-DRIVE Center for the subaward from Stanford with award number 80NSSC22M0162. AN acknowledges NASA DRIVE Center COFFIES grant 80NSSC20K0602. ASWT has been supported by Funda¸c˜ao de Amparo `a Pesquisa do Estado de S˜ao Paulo (FAPESP) (grant 2020/14162-6).
• Keywords: Solar activity (1475), solar flares (1496), solar storm (1526), solar active regions (1974).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Mactaggart, Dr David
• Authors: Raphaldini, B., Dikpati, M., Norton, A. A., Teruya, A. S. W., McIntosh, S. W., Prior, C. B., and MacTaggart, D.
• College/School: College of Science and Engineering > School of Mathematics and Statistics > Mathematics
• Journal Name: Astrophysical Journal
• Publisher: American Astronomical Society
• ISSN: 0004-637X
• ISSN (Online): 1538-4357
• Copyright Holders: Copyright © 2023 The Authors
• First Published: First published in Astrophysical Journal 958:175
• Publisher Policy: Reproduced under a Creative Commons License