Evolution of solar active regions: Detecting the emergence of new magnetic field through multifractal segmentation

Abstract

New emerging magnetic flux is identifed using a multifractal segmentation method used to investigate regularities in the evolution of active regions and activity complexes. The SOLIS, MDI SOHO, and SOT Hinode magnetograms were used. Observations of the active region NOAA 10488 on October 26-28, 2003 indicate considerable variability of areas of new magnetic flux on a characteristic time scale of 1-2 h. Broadening of the multifractal spectrum in magnetogram sections corresponding to areas of new flux leads to their detection on segmented multifractal images corresponding to the minimal fractal dimensions. New regularities in the emergence of magnetic flux in the 24th solar cycle are studied using data obtained in 2010-2014. A positive correlation of the time variations of areas of new magnetic flux of N and S polarities is predominant at all stages in the development of the cycle. A gradual decrease in the correlation coefficient during 2010-2014 is associated with the progressive complexity of the relationships among active regions, which leads to their clustering into activity complexes.

Photospheric plasma and magnetic field dynamics during the formation of solar AR 11190

“…A final interesting field for which this research might yield a new approach is the field of flux emergence studies. Authors like Golovko & Salakhutdinova (2015) have pointed out that flux emergence can be detected in image data by algorithms using sophisticated multi-fractal spectral analysis and segmentation. On the other hand, we have shown now that not only the structures within the FOV are changed (classically the granulation pattern gets elongated, which can be used within segmentation algorithms) but that the flow field changes remarkably leading to changed velocity distributions.…”