Power spectrum and Fisher–Shannon information plane analysis of tidal records

The time dynamics of tidal fluctuations measured in three sites in Bahia Blanca Estuary (central Argentina), Ingeniero White, Puerto Belgrano and Torre Mareografica, are analyzed. To investigate the time series of the tidal waves we used two different approaches: the power spectral density (PSD) and the Fisher–Shannon (FS) information plane. The PSD permitted: (i) the identification of diurnal, semi-diurnal and higher frequency cycles in all the three tidal signals, and (ii) the detection of two different dynamical regimes (scaling and white-noise), involving respectively timescales lower and higher than about 2–2.5 days. The FS method, which allows to gain insight into the complex structure of a time series, quantifying its degree of organization and order, was applied to the residual tidal series (after removing the main cycles) and permitted to identify a period of low organization in the tidal signal measured at Puerto Belgrano.