ИСТИНА

The features of temporal realizations of various geophysical fields and their seasonal variations-seismic catalogs, noise at receiving stations, gps variations, magnetic field, apparent electrical resistance, etc. are considered. The problem of excluding seasonal variations from the initial signal to search for the expected useful signal is solved. An overview of the presence of a seasonal signal in real time series of various geophysical parameters is given. A wide variety of seasonal signals has been established even for the same geophysical process; examples of the absence of a season or the doubtfulness of its presence are given. Examples of the nonlinear contribution of the season are considered. Mechanisms for creating artificial time series containing signs of natural geophysical time variations are considered. A multiplicative model of a mixture of random noise and Flicker noise with various types of seasonal variations and other periodic components is considered. Various cases are shown when the season has a visible contribution to the model, but is not expressed in any way in the resulting series. At the same time, neither the construction of the average season nor the spectral assessment give a significant extremum for the period of the year. The reasons for this unusual result are given. A model for creating a random catalog of events with signs of a real earthquake catalog is considered and the noise hypothesis of the appearance of a season in such a catalog is estimated. For this, modulation of such a catalog with a periodic seasonal signal was used. The noise hypothesis was tested both for events that did not fall under the noise and for those that were above the noise. When assessing the accuracy of the selection of the expected useful signal, the analysis of the possibility of filtering seasonal variations in both natural and artificial time series is carried out. Examples of dubious interpretation of real data within the framework of certain techniques are given. The use of such methods for our earlier study of periodicity in various geophysical processes is critically examined. Examples of successful identification of seasonal variations for real geophysical time series obtained in Kyrgyzstan are given. The efficiency of mutual filtering of the series for the selection and exclusion of the season is estimated and the dimension of the set of series is estimated.