Spatial and temporal distribution of solar green-line corona for Solar Cycles 18 – 24
Takalo, Jouni (2022-09-13)
Takalo, J. Spatial and Temporal Distribution of Solar Green-Line Corona for Solar Cycles 18 – 24. Sol Phys 297, 118 (2022). https://doi.org/10.1007/s11207-022-02050-0
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https://urn.fi/URN:NBN:fi-fe2022102062639
Tiivistelmä
Abstract
The homogeneous coronal data set (HCDS) of the green corona (Fe XIV) and the coronal index of solar activity (CI) have been used to study the time–latitudinal distribution in Solar Cycles 18 – 24 and compared with similar distribution of sunspots, the magnetic fields, and the solar 10.7 cm radio flux. The most important results are: i) the distribution of coronal intensities related to the cycle maximum are different for individual cycles, ii) the poleward migration of the HCDS from mid-latitudes in each cycle exists, even in the extremely weak Cycle 24, and the same is valid for the equatorward migration, iii) the overall values of HCDS are slightly stronger for the northern hemisphere than for the southern one, iv) the distribution of the HDCS is in coincidence with the strongest photospheric magnetic fields (B>50 Gauss) and histograms of the sunspot groups, v) the 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 components account for 87.7% and 7.3% of the total variation of the CI. Furthermore, the second PCA component of the green corona was quite different for Cycle 21, compared with other cycles.
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