2025/10/21 by Harshita Gandhi, Gandhi, Harshita, Huw Morgan +1
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #FOS: Physical sciences #Geomagnetism and Paleomagnetism Studies #Ionosphere and magnetosphere dynamics #Solar and Space Plasma Dynamics #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2510.19125
openalex publication_date 2025/10/21 · openalex created_date 2025/10/24 · openalex updated_date 2026/07/28
Understanding how active-region properties influence coronal mass ejection (CME) dynamics is essential for constraining eruption models and improving space-weather prediction. Magnetic diagnostics derived above polarity inversion lines (PILs), including the critical height (h\rm crit) of torus instability onset, the overlying field strength (B\rm t), and ribbon flux (R\rm f), provide physically motivated measures of eruption onset. The two main aims of this work are to (i) show that h\rm crit and B\rm t can equally well predict CME speeds when evaluated over the region of interest (ROI) not directly above the PIL, and (ii) assess the value of h\rm crit, B\rm t and R\rm f in predicting CME speed. Photospheric magnetograms are modeled with potential-field extrapolations to obtain decay index profiles. Critical heights above PILs correlate strongly with 3D CME speed (r = 0.71). Using ROIs of ≈ 1.8, 3.7, and 7.3 Mm), centered on the PIL, weighted h\rm crit from the 7.3x7.3 ROI provides the strongest correlation (r = 0.73), while mean B\rm t at 150 Mm is weaker (r = 0.33). Combining both offers little improvement (r = 0.74), confirming h\rm crit as the dominant predictor. CME speed correlates moderately with B\rm t × R\rm f (r = 0.44), and highest when combined with h\rm crit (r = 0.76). Thus, in potential field models, ROI-based critical heights are as predictive as those above the PIL, indicating that the broader active-region field structure is equally valid as a diagnostic. When all parameters are considered together, h\rm crit alone consistently shows the highest predictive power for CME speed.