Spatial and Temporal Distribution of Solar Green Line Corona for Solar Cycles 18-24

TL;DR

This study analyzes the spatial and temporal patterns of the solar green corona across solar cycles 18-24, revealing cycle-dependent intensity distributions, hemispheric asymmetries, and migration trends linked to magnetic activity.

Contribution

It provides a comprehensive analysis of coronal intensity distributions over multiple cycles, highlighting differences and migration patterns using a homogeneous data set and principal component analysis.

Findings

Coronal intensities vary with cycle maximum and differ among cycles.

Poleward and equatorward migrations of coronal features are observed in all cycles.

Hemispheric asymmetry shows slightly stronger signals in the northern hemisphere.

Abstract

Homogeneous coronal data set (HCDS) of the green corona (Fe XIV) and coronal index of the solar activity (CI) have been used to study time-latitudinal distribution in solar cycles 18-24 and compared with similar distribution of sunspots, the magnetic fields and the solar radio flux 10.7 cm. The most important results are: (a) distribution of coronal intensities related to the cycle maximum are different for individual cycles, (b) the poleward migration of the HCDS from mid latitudes in each cycle exists, even in extremely weak Cycle 24, and the same is valid for the equatorward migration (c) the overall values of HCDS are slightly stronger for the northern hemisphere than for the southern one, (d) distribution of the HDCS are in coincidence with strongest photospheric magnetic fields (B>50 Gauss) and histogram of the sunspot groups, (e) Gnevyshev gap was confirmed with at least 95% confidence in the CI, however, with different behavior for odd and even cycles. Principal component analysis (PCA) showed that the first and second component account for 87.7% and 7.3% of the total variation of the CI. Furthermore, the PC2 of the green corona was quite different for cycle 21, compared with other cycles.