Abstract
Using the annual number of geomagnetically quiet days (aa < 20 γ) for the year after the solar minimum, this precursor method predicts that the maximum sunspot number for cycle 23 will be 140 + 32, indicating that cycle 23 will be similar to cycles 21 and 22.
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Mendoza, B., Ramírez, J. A straightforward estimation of the maximum sunspot number for cycle 23. Annales Geophysicae 17, 639–641 (1999). https://doi.org/10.1007/s00585-999-0639-7
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DOI: https://doi.org/10.1007/s00585-999-0639-7