Space Climate
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Fig. 10

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Comparison of the latest values of the Ri index and the Boulder sunspot number from 1991 to the beginning of 2012 (source: NGDC, Boulder. Index based on a few US professional observatories). The lower curve, which gives the ratio and 3σ limits, shows a reversal of the cycle 23 deviation over the early part of cycle 24, like in Fig. 9. Here, the ratio has fully recovered its pre-2000 value by the end of 2011.

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