Abstract.The relationship between the solar polar magnetic field reversal and coronal hole evolution is investigated for the time interval from 1996 to 2001. The distribution of coronal holes shows some evolutionary changes in relation to the polarity reversals, and these changes appear to be coordinated with changes in the global magnetic field structure, suggesting that the polar reversal originates from global processes. There are periods when the character of the coronal hole distribution on the solar disk changes significantly, indicating that the magnetic field structure changes. These can be interpreted as periods of rearrangement of the multipole magnetic field structure. It is found that the evolution of the geometric structure of the photospheric magnetic field during these periods is not characterized by a continuous transition from one dominant structure to another, but by relatively sudden rearrangement of the dominant geometrical structure of the magnetic field. These coronal holes and photospheric magnetic field rearrangements coincide with the polar photospheric magnetic field strength variations. The minimum phase of the solar cycle is dominated by the dipole component of the global solar magnetic field. The zonal magnetic field structure and zonal non-polar coronal hole distribution existed at that time. The sectorial magnetic field structure appears when the polar field strength reaches 0.7 of its maximum value in the corresponding hemisphere. This structure was established at different times in each hemisphere. In the north hemisphere it has existed since November 1998 and in the south hemisphere it has existed since October 1997. The rearrangement from one configuration to another occurs during a short time period, about 1 ÷ 2 solar rotations. The coronal hole number and area evolution indicates a redistribution of positive-polarity and negative-polarity photospheric magnetic fields inside these longitudinal sectors, which reflects the solar polar field reversal.

Coronal hole spatial-temporal evolution is studied and comparison made with that of the solar global magnetic field in cycles 21 -23 (1976 -2012). The latitude-longitude distribution dynamics of coronal holes and the regularities in the global magnetic field associated with the solar polar field reversal are analyzed. Polar and non-polar coronal hole populations are considered. The investigation reveals some temporal and spatial regularities in coronal hole distributions that match well the global magnetic-field cycle evolution. The results show that the non-polar coronal hole longitudinal distribution follows all configuration changes in the global magnetic-field structure. Reorganizations of the global magnetic-field and coronal hole distributions occur simultaneously during a time interval of a few solar rotations. The cycle evolution of the non-polar coronal holes reflects the transition of the solar global magnetic field from the zonal structure to sectorial and vice versa. Two different type waves of nonpolar coronal holes are revealed from their latitudinal distribution. The first one is short poleward waves. They trace the poleward motion of the unipolar photospheric magnetic fields from approximately 35 • to the associated pole in each hemisphere and the redevelopment of a new-polarity polar CH. Although they start the poleward movement before the change of the polar magnetic field in the associated hemisphere, they reach the pole after the polar reversal. The other type of non-polar CH wave forms two sinusoidal branches associated with the positive-and negative-polarity magnetic fields. The complete period of the wave was equal to ≈268 CRs (22 years). These wave CHs arrive at high latitudes during declining phases when the new polarity polar CHs are already completely formed.

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The number of coronal mass ejections (CMEs) and their parameters and cycle variations were investigated and compared to the photospheric magnetic field evolution in cycles 23 and 24. The Coordinated Data Analysis Workshops (CDAW) catalog of white-light CMEs detected by the Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph coronagraphs and the data on the photospheric magnetic fields from the Kitt Peak Vacuum Telescope Spectromagnetograph (KPVT/Spectromagnetograph) and the Synoptic Optical Long-term Investigations of the Sun Vector-Spectromagnetograph (SOLIS/VSM) were used. The results suggest that not only did the number of CMEs increase in cycle 24, but that their parameters, cycle variations, distributions, and dependencies on the photospheric magnetic fields were also different. Various CME categories behave in different ways during solar cycles. The differences in the number and parameters of CMEs and their cycle variations may be related to the differences in the photospheric magnetic fields during the cycles. The strong photospheric magnetic fields maintained approximately the same strength from cycle 23 to cycle 24, whereas the weak fields became weaker and the area they occupied increased. Taking into account that the global magnetic field diminished from cycle 23 to cycle 24, the increase in the number of CMEs in cycle 24 can be understood. A detailed analysis of the similarities and differences in CME parameters and their cycle evolution indicates that, along with the influence of changes in the CME detection mode in 2004 and 2010, the changes in CME rate and parameters were also associated with real differences in the behavior of strong and weak photospheric magnetic fields in cycles 23 and 24.

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