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Fig. 3


Radial component of the surface magnetic field for the reference case. The upper panel shows a time-latitude diagram. The lower panel gives the polar fields, defined as the average radial field strength beyond ± 70° latitude (black curve) and the sunspot numbers (red curve). The vertical line indicates the time until which RGO sunspot group area data are available. The correlation coefficient of the maxima of the polar fields and the subsequent maxima of sunspot number for cycles 15 to 21 is 0.85.

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