Since we aim to investigate the chaotic/stochastic features of
the solar activity cycle and to discuss them in terms of spatiotemporal
and/or dynamical complexity, we must determine the
minimum number of modes required to reconstruct the butterfly
diagram without losing relevant information about the solar cycle.
This can be achieved by studying the average error δ(N∗
)
as a function of the truncation order N∗ of the reconstructed butterfly
diagram (see Eq. (6)), defined by