Abstract
Abstract The paper presents study the 11-year dynamics of solar activity on the basis of new observational material on coronal holes (CHs) and sunspots in the period from May 13, 2010 to May 13, 2021. We used the Heliophysics Event Knowledgebase (HEK) to obtain information on CHs areas. For 11 years of observations, we processed about 18000 CHs. Slightly more than 8000 are polar, the rest are nonpolar CHs. The statistical volume of the presented material is quite extensive and gives grounds for the study of the dynamics of different types of CHs during the cycle. Our research has shown: in the 24th solar activity cycle, the South led for polar CHs and the North led for nonpolar ones. We established a relationship between the number and area of CHs and the phase of the solar cycle. The number and daily total area of polar CHs increases at the minima of solar activity and decreases at the maximum of the cycle. This is consistent with the general concept of polar CHs as the main source of the solar dipole magnetic field. An asymmetry in both the number and areas of polar coronal holes in the northern and southern hemispheres is observed. It is shown that the areas of nonpolar CHs change quasi-synchronously with sunspot activity, which suggests a physical connection between these two phenomena.
Highlights
The solar cycle is a dynamo process in which poloidal magnetic field is twisted by differential rotation into a toroidal field and that toroidal field is transformed by cyclonic convection back into a poloidal field of the opposite sign (Parker 1955; Dikpati and Charbonneau 1999)
Our research has shown: in the 24th solar activity cycle, the South led for polar coronal holes (CHs) and the North led for nonpolar ones
The number and daily total area of polar CHs increases at the minima of solar activity and decreases at the maximum of the cycle
Summary
The solar cycle is a dynamo process in which poloidal magnetic field is twisted by differential rotation into a toroidal field and that toroidal field is transformed by cyclonic convection back into a poloidal field of the opposite sign (Parker 1955; Dikpati and Charbonneau 1999). The 11-year cycle is characterized by periodic changes in measures of solar activity such as the number of sunspots, coronal holes, and others. The software performs the segmentation of the Sun images on active regions, quiet Sun, and CHs and make records into the HEK catalogs every four hours These databases made it possible to obtain an array of daily total CHs areas for the period May 13, 2010–May 13, 2021. Polar holes behave in accordance with the general dipole of the solar magnetic field Their physical nature is quite different and nonpolar CHs must most likely be associated with the sunspots activity. We drew this conclusion from the number of coronal holes. We turn to the analysis by the areas of coronal holes (Sch)
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