Solar Coronal Rotation from 1973 to 2017: An Analytical Approach Based on Coronal Hole Areas

Abstract Solar coronal rotation exhibits significant complexity, and its relationship with the 11 yr solar cycle remains poorly understood. Using 597 McIntosh synoptic maps (CR1601–CR2197), we construct the temporal evolution of coronal rotation by performing cross-correlation analysis of coronal hole areas between consecutive Carrington rotations. Results show coronal rotation rate decreases from the equator to mid-latitudes (45°–60°), then increases at high latitudes (>60°). Comparison across solar cycles 21–24 reveals that cycle 23 displays the highest equatorial rotation rate and the strongest differential rotation. Equatorial rotation rates in odd-numbered cycles are generally higher than in preceding even-numbered ones. The latitudinally averaged rotation rate reaches a minimum near solar maximum and recovers during the declining phase, likely due to the latitudinal migration of coronal holes. Hemispheric asymmetry analysis shows no significant north–south difference in rotation rates, contrasting sharply with the strong asymmetry in sunspot distributions. Time series analysis of rotational parameters A, B, and C reveals a significant negative correlation between A and B, and a positive correlation between A and C. Singular spectrum analysis identifies prominent 5.6 and 6.9 yr periods in all three, with only C showing a strong 10 yr period.