Turkish Journal of Physics




In this study, we modified the previously introduced X-ray flare production potential (FPP) of each modified Zurich sunspot group based on its X-ray flare peak flux. Then, using these FPPs, the daily total sunspot number (Zurich number) calculation equation was modified; thus, new sunspot number data (CRz) were produced. We also compared ISSN and CRz with some geomagnetic indices (Dst, the maximum CME speed, and Ap indices). We found that the CRz data describe the geomagnetic indices quite well compared to ISSN. By using the regression equation between CRz and the sunspot area, the CRz dataset was recalculated back to 1874. Those reconstructed datasets were compared to observational data, and it was found that reconstructed and observed monthly datasets show very good agreement. The only small differences exist in maxima and minima of cycles.


Sunspot, sunspot classification, sunspot number, solar X-ray flares

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