Reconstruction of Grand Minima of Solar Activity From ... data: Linear and nonlinear signal analysis

Using a special technique of data analysis, we have found 34 grand minima of solar activity in a 7700--year--long \Delta 14 C record. The method used rests on a proper filtering of the \Delta 14 C record and the extrapolation of verifiable results for the later history back in time. Additionally, we have applied a method of nonlinear dynamics, the recurrence rate, to back up the results. Our findings are not contradictory to the record of grand minima by Eddy [1977] but constitute a considerable extension. Hence it has become possible to look closer at the validity of models. This way, we have tested the model of Barnes et al. [1980]. There are hints for that the grand minima might solely be driven by the 209--year period found in the \Delta 14 C record. Introduction The long--term behavior of solar activity is most obvious in the occurrence of grand minima, as rediscovered by Eddy [1977]. By evaluating historical sunspot observations, Eddy claimed the existence of the so--cal..