Predictions of Solar Cycle Amplitude using Solar Cycle Length: fact or artefact?

Vaquero J.M., Trigo R.M.
Solar Physics, 250, 199-206

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In this work, the evolution of the relationship between Solar Cycle Length of solar cycle n (SCLn) and Solar Cycle Amplitude of the solar cycle n + 1 (SCAn+1) is studied by using the RZ and RG sunspot numbers. We conclude that this relationship is only strongly significant in a statistical sense during the first half of the historical record of RZ sunspot number whereas it is considerably less significant for the RG sunspot number. In this sense we assert that these simple lagged relationships should be avoided as a valid method to predict the following solar activity amplitude.