The Solar Situation Awareness and Flare Forecasting Dataset provides 14 years of co-registered SDO/HMI, AIA, and Hα daily products with expert-reviewed active region, coronal hole, and filament annotations plus 24-hour flare labels, supporting AI-based forecasting.
Persistent magnetic flux emergence with perpendicular separation directions in AR 13842 rapidly formed a collisional shearing PIL, with frequent flux cancellations there, leading to repeated magnetic flux rope formations and multiple large flares. The pre-flare decreases in the sheared PIL’ s area and free-energy density may serve as a promising precursor for major eruptive flares.
Magnetofrictional simulations of Active Region 13500 reproduce its transition from stability to eruption and show that a massive sigmoid flux rope formed during the decay phase. The eruption began when the current-carrying helicity ratio reached about 0.3, indicating that helicity-based markers can help diagnose the eruptive potential of active regions.
HMI data from Solar Cycle 24 data are used to determine how often the Sun emerges sunspots in activity nests. It is found that the Sun shows moderate nesting behavior with 41% (48%) of AR magnetic flux found in northern (southern) hemisphere located in nests. The maximum number of nests are found with slightly prograde rotational velocities, and the nesting behavior is asymmetric in the hemispheres.
A statistical comparison between HMI vector magnetograms and line-of-sight–derived radial fields shows that LOS-based estimates systematically underestimate the true radial field, with the bias increasing toward the limb. A numerical modeling demonstrate that this center-to-limb variation in the underestimation of radial field arises from non-radial magnetic field inclinations.
A robust, calibrated method for measuring sunspot areas from SOHO/MDI and SDO/HMI full-disk images enables a consistent, observer-independent, long-term catalogue of daily sunspot areas, revealing detailed patterns of sunspot group area evolution and solar cycle variability.
Through MHD simulations of flux eruptions, the study finds that the current helicity decreases prior to eruptions and then reverses to increase afterward. By examining multiple flare events, the authors identified observational evidence supporting these simulation results.
Multiple X-class flares and CMEs were produced by AR 13664/8 during the Mother’s Day week of 2024. This study suggests that predicting the locations of magnetically complex active regions, and studying and tracking their eruptive states using different proxy parameters can greatly improve the capability to forecast intense storms.
Each solar active region (AR) has its unique shape, size, and lifetime. In this work, the authors developed a method to ‘average’ bipolar ARs by normalizing their size, orientation, and timing, thereby revealing the typical properties of an AR and its evolutionary pattern.
It is widely known that magnetic fields suppress convection, but this effect has not been quantitatively assessed. Using vector magnetograms from HMI observations, the authors measured the advection speeds of magnetic flux as a function of field strength and found that the speeds steadily decrease with increasing field strength.