Properties of solar activity derived from cosmogenic radionuclides

During the past several cycles the average activity was very high. This raises the question whether the present period of high solar activity is likely to terminate soon or even to be followed by another (Maunder-like) grand minimum. Using cosmogenic radionuclides such as 10Be in ice cores, changes in the open magnetic field of the Sun can be traced back many thousand of years providing unprecedented information about the history of solar activity. The record of solar activity derived from 10Be can provide a number of constrains for solar dynamo models as well as helping answer questions related to solar activity. A detailed statistical analysis of the cosmogenic record allows us to demonstrate that the recent period of high solar activity is indeed coming to an end. Frequency analysis of the solar modulation potential reveals the presence of significant periodicities, namely around 2200 years (Hallstatt), 980 y (Eddy), 208 y (de Vries) and 90 y (Gleissberg.)