Indeed, it has been shown (Hoyng et al. 1994) that in a simple
axisymmetric mean-field dynamo, random α-fluctuations can
account for several features of the observed solar cycle. In particular,
these random fluctuations, expected to arise from the turbulent
convection, are characterized by a correlation time much
shorter than any characteristic dynamo period. We believe that the second regime in the eigenvalue spectrum could be a manifestation
of these random fluctuations in the α-effect. This hypothesis
is supported by the values of the Lyapunov exponents,
which are higher in the second regime than the first, therefore
implying a higher variability.