Abreu, J.

Albert, C.

Beer, J.

Ferriz-Mas, A.

McCracken, K.

Steinhilber, F.

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Solar Phys (2014) 289:2343–2344DOI 10.1007/s11207-014-0473-2Response to: “Critical Analysis of a Hypothesisof the Planetary Tidal Influence on Solar Activity”by S. Poluianov and I. UsoskinJ.A. Abreu · C. Albert · J. Beer · A. Ferriz-Mas ·K.G. McCracken · F. SteinhilberReceived: 11 November 2013 / Accepted: 2 January 2014 / Published online: 16 January 2014© Springer Science+Business Media Dordrecht 2014In their analysis of our hypothesis of a planetary influence on solar activity Poluianov andUsoskin (P&U) claim that the ‘peaks in long-period range of the torque spectrum are arte-facts caused by the calculation algorithm’ and that ‘the statistical significance of the waveletcoherence is overestimated’.We will show here that the periodicities between 60 and 600 years which we found inthe torque exerted by the planets on the tachocline are not artefacts. However, averagingthe daily torque data has an effect on the corresponding spectrum. In our paper A12 (Abreuet al., 2012) we did not use wavelet coherence to estimate the statistical significance of thediscussed periodicities. Nevertheless, we will address the question of the significance of theperiodicities as well.All existing records of solar activity based on cosmogenic radionuclides have a tempo-ral resolution of one year at best. We therefore decided to average the daily x, y, and zcomponents of the torque over one year. This procedure is different from the classical alias-ing problem, which occurs by resampling the data in discrete steps of one year, but, as werealized later, it has an effect on the resulting spectrum.A detailed spectral analysis reveals the following.J.A. Abreu (B) · C. Albert · J. Beer · F. SteinhilberEawag, Swiss Federal Institute of Aquatic Science and Technology, Postfach 611, 8600 Duebendorf,Switzerlande-mail: jose.abreu@eawag.chA. Ferriz-MasDepartemento the Física Aplicada, Universidade de Vigo, Vigo, SpainA. Ferriz-MasInstituto de Astrofísica de Andalucía (IAA/CSIC), Granada, SpainK.G. McCrackenUniversity of Maryland, College Park, USA2344 J.A. Abreu et al.i) All the five periodicities we discuss in A12 are present in the daily torque data. However,their amplitudes are relatively small. In the ranking of the strongest periodicities theyshow up on positions between 15 and 30.ii) As a result of the averaging over one year the five periodicities move up to positionsbetween 1 and 10.iii) Averaging over two or more years decreases the amplitudes again.iv) The reduction of Equations (1) – (3) to (5) – (7) is incorrect and leads to a time serieswhich is different from ours. Setting all the geometrical factors to 1 is equivalent toassuming a spherical tachocline in which case the planetary torque vanishes.v) We do not know whether the shift of the 506-year peak to 430 years in Figure 3 (toppanel), which P&U consider as ‘a minor difference’, is the result of this. In any case itconflicts with their Figures 4 and 5 where it appears correctly at about 506 years.vi) We would like to conclude our comments about artefacts by mentioning that plane-tary torque requires an amplification mechanism in the Sun in order to modulate thelong-term heliomagnetic activity. Whatever this physical mechanism will be, we cannotexclude that it may act as a filter.In the second part of their paper P&U criticize our significance analysis. We stress that inour paper we used wavelet techniques only in the context of phase analysis and not for esti-mating the significance. Figure 6 in P&U shows the wavelet coherence for two periodicitieswe do not find in our data. However, the crucial question to be answered is: what is the prob-ability that all five spectral lines are simultaneously present by chance in a time series of thesame length as our records of solar activity? Monte Carlo techniques show unambiguouslythat this probability is lower than 10−4.ReferenceAbreu, J.A., Beer, J., Ferriz-Mas, A., McCracken, K.G., Steinhilber, F.: 2012, Is there a planetary influenceon solar activity? Astron. Astrophys. 548, A88.

Response to: "Critical Analysis of a Hypothesis of the Planetary Tidal Influence on Solar Activity” by S. Poluianov and I. Usoskin

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Response to: "Critical Analysis of a Hypothesis of the Planetary Tidal Influence on Solar Activity” by S. Poluianov and I. Usoskin

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