Abstract
This article is an update of a study (Tapping and Valdès in Solar Phys. 272, 337, 2011) made in the early part of Cycle 24 using an intercomparison of various solar activity indices (including sunspot number and the 10.7 cm solar radio flux), in which it was concluded that a change in the relationship between photospheric and chromospheric/coronal activity took place just after the maximum of Cycle 23 and continued into Cycle 24. Precursors (short-term variations) were detected in Cycles 21 and 22. Since then the sunspot number index data have been substantially revised. This study is intended to be an update of the earlier study and to assess the impact of the revision of the sunspot number data upon those conclusions. This study compares original and revised sunspot number, total sunspot area, and 10.7 cm solar radio flux. The conclusion is that the transient changes in Cycles 21 and 22, and the more substantial change in Cycle 23, remain evident. Cycle 24 shows indications that the deviation was probably another short-term one.
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Acknowledgements
The authors owe a great vote of thanks to the Royal Observatory, Belgium, for the ongoing effort in providing the longest-duration, consistent direct record of solar activity available. Thanks are also due to the Royal Greenwich Observatory and now NASA for providing the also long-duration time-series of total sunspot area data. This research was supported by the National Research Council of Canada. One of the authors (CMM) was supported by the NRC Student Programme and by the University of Victoria, British Columbia.
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Tapping, K., Morgan, C. Changing Relationships Between Sunspot Number, Total Sunspot Area and \(F_{10.7}\) in Cycles 23 and 24. Sol Phys 292, 73 (2017). https://doi.org/10.1007/s11207-017-1111-6
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DOI: https://doi.org/10.1007/s11207-017-1111-6