Statistical Comparison between Pores and Sunspots during the Time Interval 2010–2023

Abstract

To reveal the physical properties of pores and sunspots varying with solar cycle, we carried out a statistical comparison among pores, transitional sunspots, and mature sunspots using Solar Dynamics Observatory/Helioseismic and Magnetic Imager from 2010 April to 2023 July. The OTSU method and region-growing algorithm were combined to detect umbrae of 11,876 sunspots covering solar cycles 24 and 25. The relationships between umbral area, continuum intensity ( I ), line-of-sight (LOS) magnetic field strength ( B _los ), and line-of-sight velocity ( V _los ) of umbrae were investigated in detail. The main conclusions are as follows. (1) The steepness between the total magnetic flux and total area of transitional sunspots appears to be flattened in each phase of the observed solar cycles, and does not have a significant variation over the solar cycle. (2) For three groups of sunspots, the umbral physical parameters’ means and their correlations show only minor variations with the solar cycle, which are in error ranges. (3) As the mean umbral LOS magnetic field strength increases, the correlation of the umbral I – B _los increases. The flattening of transitional sunspots in total area–total magnetic flux scatter is related to the evolution of sunspots itself, and may not correspond to the solar cycle. The umbral physical parameters and their correlations do not exhibit a discernible regularity over the solar cycle. Our analysis results contribute to a more comprehensive understanding of the dynamic processes of sunspot magnetic fields and give a new perspective on revealing the physical features of vertical magnetic flux tubes.

Keywords

• Sunspots
• Solar magnetic fields
• Solar photosphere