Alt! Fermate tutti i commenti che già vi frullano per la testa, non si parla di energia, per una volta non ho voglia di litigare. Si parla di clima, ovvero della relazione Sole-Clima.
Da qualche anno a questa parte il nostro esperto di riferimento è Nicola Scafetta. Abbiamo pubblicato dei commenti praticamente a tutti i suoi articoli sull’argomento, prendendoci anche il lusso di ospitare direttamente la sua firma sulle nostre pagine.
L’ultimo articolo di cui abbiamo parlato è quello in cui si ipotizza una relazione tra le maree planetarie, il Sole appunto e le dinamiche climatiche – in termini di temperatura – sul nostro Pianeta. Una delle critiche più accese che è stata mossa al lavoro di Scafetta, è stata quella dell’assenza di un meccanismo fisico che spiegasse questa relazione, dal momento che il forcing indotto dalle maree planetarie sulla nostra stella, sarebbe troppo piccolo per giustificare le oscillazioni della sua attività.
Qualche giorno fa Nicola Scafetta mi ha mandato una copia del suo più recente lavoro:
Does the Sun work as a nuclear fusion amplifier of planetary tidal forcing? A proposal for a physical mechanism based on the mass-luminosity relation – Journal of Atmospheric and Solar-Terrestrial Physics
Il paper è disponibile sulla pagina Web personale dell’autore, dove trovate anche tutte le altre sue pubblicazioni. Come leggiamo anche da Tallbloke, altro blog climatico che ha dedicato attenzione a questo lavoro, questa volta Scafetta ha dato il massimo. Dopo aver lungamente ipotizzato una relazione tra le maree planetarie e l’attività solare, costruendo anche un modello di armoniche che ricostruisce molto efficacemente le temperature medie superficiali globali, la cui proiezione nel futuro sta facendo molto meglio delle simulaizoni climatiche classiche, e dopo aver identificato una elevata correlazione tra la ciclicità dei moti planetari e l’attività solare, finalmente ci propone un meccanismo fisico in grado di amplificare il forcing esercitato dalle maree planetarie. Una volta applicato il coefficiente di amplificazione, le oscillazioni dell’ouput di luminosità del Sole risultano essere compatibili con quanto misurato dai sensori satellitari ACRIM per le fluttuazioni della radiazione solare totale.
Di seguito l’abstract di questo ultimo paper:
Numerous empirical evidences suggest that planetary tides may influence solar activity. In particular, it has been shown that: (1) the well-known 11-year Schwabe sunspot number cycle is constrained between the spring tidal period of Jupiter and Saturn, ~ 9.93 year, and the tidal orbital period of Jupiter, ~ 11.86 year, and a model based on these cycles can reconstruct solar dynamics at multiple time scales (Scafetta, in press); (2) a measure of the alignment of Venus, Earth and Jupiter reveals quasi 11.07-year cycles that are well correlated to the 11-year Schwabe solar cycles; and (3) there exists a 11.08 year cyclical recurrence in the solar jerk-shock vector, which is induced mostly by Mercury and Venus. However, Newtonian classical physics has failed to explain the phenomenon. Only by means of a significant nuclear fusion amplification of the tidal gravitational potential energy dissipated in the Sun, may planetary tides produce irradiance output oscillations with a sufficient magnitude to influence solar dynamo processes. Here we explain how a first order magnification factor can be roughly calculated using an adaptation of the well-known mass-luminosity relation for main-sequence stars similar to the Sun. This strategy yields a conversion factor between the solar luminosity and the potential gravitational power associated to the mass lost by nuclear fusion: the average estimated amplification factor is A ~ 4,25 x 106. We use this magnification factor to evaluate the theoretical luminosity oscillations that planetary tides may potentially stimulate inside the solar core by making its nuclear fusion rate oscillate. By converting the power related to this energy into solar irradiance units at 1 AU we find that the tidal oscillations may be able to theoretically induce an oscillating luminosity increase from 0.05–0.65 W/m2 to 0.25–1.63 W/m2, which is a range compatible with the ACRIM satellite observed total solar irradiance fluctuations. In conclusion, the Sun, by means of its nuclear active core, may be working as a great amplifier of the small planetary tidal energy dissipated in it. The amplified signal should be sufficiently energetic to synchronize solar dynamics with the planetary frequencies and activate internal resonance mechanisms, which then generate and interfere with the solar dynamo cycle to shape solar dynamics, as further explained in Scafetta (in press). A section is devoted to explain how the traditional objections to the planetary theory of solar variation can be rebutted.
E poi ancora le conclusioni:
Numerous empirical evidences indicate that planetary tides can influence solar dynamics. High resolution power spectrum analysis reveals that the sunspot number record presents three frequencies at about Jupiter/Saturn’s spring tidal period of 9.93 years, at 10.8770.1 and at Jupiter period 11.86 years. In addition, the alignment patterns of the sub-systems of Venus–Earth– Jupiter and Mercury–Venus produce major resonance cycles at about 11.05–11.10 years, which coincides with the average length of the observed Schwabe sunspot cycles since 1750. Thus, the Schwabe solar cycle is reasonably compatible with the tidal cycles produced by the five major tidal planets: Mercury, Venus, Earth, Jupiter and Saturn. More details are found in Scafetta (in press), where it is shown how to reconstruct solar dynamics at multiple time scales using some of these frequencies. Despite numerous empirical results, a planetary-solar link theory has been found problematic in the past mostly because the gravitational tides induced by the planets on the Sun are tiny, as deduced from the tidal Eq. (14). The major tidal planets (Mercury, Venus, Earth and Jupiter) would produce tides of the order of a millimeter due to the fact that the tidal elongation is proportional to R4S : see Eq. (14). However, it is the tidal work on the Sun that physically matters, and we have shown that the total work that the planetary tides may release to the Sun is proportional to R5 S . Indeed, the tides should move up and down the entire column of solar mass. The tidal movement consistently and continuously squeezes and stretches the entire Sun from the center to the surface. The solar mass can be moved and mixed by gravitational tidal forces also because of the fluid nature of the solar plasma. However, even in this case only a tiny fraction of the gravitational tidal energy can be released as heat to the Sun (see Eq. (18)), and nothing would be expected to happen if only released tidal gravitational energy is involved in the process, as Newtonian classical physics would predict. However, a planetary tidal massaging of the solar core should continuously release additional heat to it and also favor plasma fuel mixing. Consequently, the Sun’s nuclear fusion rate should be slightly increased by tidal work and should oscillate with the tidal oscillations. In Section 3.3 we have proposed a methodology to evaluate a nuclear amplification function (Eq. (32)) to convert the gravitational potential power released in the core by tidal work into solar luminosity. The strategy is based on the fact that nuclear fusion inside a solar core is kept active by gravitational forces that continuously compress the core and very slowly release additional gravitational energy to it, as the hydrogen fuses into helium. Without gravitational work, no fusion activity would occur either because the two phenomena are strongly coupled (Carroll and Ostlie, 2007). Thus, a simple conversion factor should exist between released tidal gravitational power and its induced solar luminosity anomaly. We can estimate it using a simple adaptation of the well-known mass-luminosity relation for mainsequence stars similar to the Sun: see Eq. (27). The average estimated amplification factor is A ~ 4.25 x 106, but it may vary within one order of magnitude. In fact, there is uncertainty about the Love number that in the case of the Sun may be larger than the used factor 3/2 (see Eq. (14)), and the effective tidal dissipation factor Q likely varies with the tidal frequency and amplitude, and may be different from the used binary-star average value Q ¼ 106 (see Eq. (18)). With the theoretical methodology proposed in Section 3.3 we have found that planetary tides can theoretically induce luminosity oscillations that are within one order of magnitude compatible with the TSI records. We have found that planetary tides may induce an oscillating luminosity increase from 0.05–0.65 W/ m2 to 0.25–1.63 W/m2. Additional synchronization and resonance processes may be activated and produce an additional dynamical amplification effect. Internal frequency-dependent damping mechanisms may also be present. The solar dynamo cycle would also contribute to the final solar cycle as explained in Scafetta (in press). Although these internal dynamic processes are not addressed in this work, planetary tides appear to be able to modulate solar activity in a measurable way and our results are consistent with the observations. Finally, we have shown that the planetary tides produce major cycles with 10, 11, 12 and 61 year periods, which correspond to the cycles observed in the sunspot number record and other solar and climate records (Ogurtsov et al., 2002; Charva´ tova´ et al., 1988; Komm et al., 2003; Scafetta, 2010). The cycles with periods of 10, 12 and 61 years are directly related to Jupiter and Saturn orbits; the 11-year cycle is the average between the 10 and 12 year Jupiter–Saturn cycles, and it is also well reproduced by the recurrent tidal patterns generated by the fast tidal cycles related to Mercury, Venus and Earth. The tidal heating generated by the two planetary subsystems (terrestrial and Jovian planets) is almost the same. So, terrestrial and Jovian planets should be both important to determine solar dynamics at multiple time scales. In particular we note from Fig. 12A that the combined tides of Jupiter and Saturn would imply an increased solar activity occurring from 1970 to 2000 with a peak around 2000 that would also be almost in phase with the 10.87- year solar dynamo cycle (Scafetta, in press): this pattern would be qualitatively consistent with the pattern shown by the ACRIM total solar irradiance composite depicted in Fig. 1 (Scafetta and Willson, 2009). The preliminary results of this paper suggest that for better understanding solar activity, the physical interaction between the planets and the Sun cannot be dismissed, as done until now. Future research should better address the nature of these couplings, which could also be used to better forecast solar activity and climate change (Scafetta, 2010, in press). In fact, planetary dynamics can be rigorously predicted.