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The Hale magnetic cycle in the north-south average of the polar field, as observed at the Wilcox Solar Observatory (http://wso.stanford.edu) in the interval 1975.5–2010 (blue) and the sunspot number curve (red) to which the sign is assigned according to the toroidal field polarity of successive Schwabe cycles. The polar maxima are numbered by the standard numbers of the next following sunspot maxima.
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