J. A Abreu et al: Is there a planetary influence on solar activity?

Here is an important step forward in the progress of the Solar-Planetary theory.  Some big names in the paleo-proxy field are starting to get behind this now. Beer, McCracken and Steinhilber and Ferriz-Mas are all co-authors on this new paper published in Astronomy and Astrophysics.  The great news is that it is open access so well done AandA! No need for me to spend ages formatting the paper’s relevant plots and text, just click and download for discussion.

H/T Ian Wilson

Is there a planetary influence on solar activity?
J. A Abreu1;2, J. Beer2, A. Ferriz-Mas3;4, K. G. McCracken5, and F. Steinhilber2
1 ETH Zurich Institut fur Geophysik, CH-8092 Zurich, Switzerland. e-mail: [email protected]
2 Eawag, Swiss Federal Institute of Aquatic Science and Technology, Postfach 611, CH-8600 D¨ubendorf, Switzerland.
3 Departamento the Fisica Aplicada, Universidade de Vigo, Spain.
4 Instituto de Astrofisica de Andalucia (IAA/CSIC), Granada, Spain.
5 University of Maryland, USA.
Received 17 Mai 2011 Accepted 17 Mai 2011

ABSTRACT

Context. Understanding the Sun’s magnetic activity is important because of its impact on the Earth’s environment. Direct observations of the sunspots since 1610 reveal an irregular activity cycle with an average period of about 11 years, which is modulated on longer timescales. Proxies of solar activity such as 14C and 10Be show consistently longer cycles with well-defined periodicities and varying amplitudes. Current models of solar activity assume that the origin and modulation of solar activity lie within the Sun itself; however, correlations between direct solar activity indices and planetary configurations have been reported on many occasions. Since  no successful physical mechanism was suggested to explain these correlations, the possible link between planetary motion and solar activity has been largely ignored.

Aims. While energy considerations clearly show that the planets cannot be the direct cause of the solar activity, it remains an open question whether the planets can perturb the operation of the solar dynamo. Here we use a 9400 year solar activity reconstruction derived from cosmogenic radionuclides to test this hypothesis.
Methods. We developed a simple physical model for describing the time-dependent torque exerted by the planets on a non-spherical tachocline and compared the corresponding power spectrum with that of the reconstructed solar activity record.
Results.We find an excellent agreement between the long-term cycles in proxies of solar activity and the periodicities in the planetary torque and also that some periodicities remain phase-locked over 9400 years.
Conclusions. Based on these observations we put forward the idea that the long-term solar magnetic activity is modulated by planetary effects. If correct, our hypothesis has important implications for solar physics and the solar-terrestrial connection.
Key words. solar-terrestrial relations, dynamo, solar wind, helioseismology, planet-star interactions, magnetohydrodynamics (MHD)
There is another paper Steinhilber has been recently involved in which is worth a look. This one examines solar activity in relation to variations in C14 and 10Be, and finds an important periodicity on the timescale of around a 1000 years. (It’s 974 actually guys)

Here’s the abstract:
Context. The variations of solar activity over long time intervals using a solar activity reconstruction based on the cosmogenic radionuclide 10Be measured in polar ice cores are studied.
Aims. The periodicity of the solar activity cycle is studied. The solar activity cycle is governed by a complex dynamo mechanism. Methods of nonlinear dynamics enable us to learn more about the regular and chaotic behavior of solar activity. In this work we compare our earlier findings based on 14C data with the results obtained using 10Be data.
Methods. By applying methods of nonlinear dynamics, the solar activity cycle is studied using solar activity proxies that have been reaching into the past for over 9300 years. The complexity of the system is expressed by several parameters of nonlinear dynamics, such as embedding dimension or false nearest neighbors, and the method of delay coordinates is applied to the time series. We also fit a damped random walk model, which accurately describes the variability of quasars, to the solar 10Be data and investigate the corresponding power spectral distribution. The periods in the data series were searched by the Fourier and wavelet analyses.
Results. The solar activity on the long-term scale is found to be on the edge of chaotic behavior. This can explain the observed intermittent period of longer lasting solar activity minima. Filtering the data by eliminating variations below a certain period (the periods of 380 yr and 57 yr were used) yields a far more regular behavior of solar activity. A comparison between the results for the 10Be data with the 14C data shows many similarities. Both cosmogenic isotopes are strongly correlated mutually and with solar activity. Finally, we find that a series of damped random walk models provides a good fit to the 10Be data with a fixed characteristic time scale of 1000 years, which is roughly consistent with the quasi-periods found by the Fourier and wavelet analyses.
Conclusions. The time series of solar activity proxies used here clearly shows that solar activity behaves differently from random data. The unfiltered data exhibit a complex dynamics that becomes more regular when filtering the data. The results indicate that solar activity proxies are also influenced by other than solar variations and reflect solar activity only on longer time scales.