Spectral methods for analyzing the rotation of solar structures

The application of spectral analysis methods for studying the rotation of solar structures is considered. The time series characterizing the time variation of the solar He I 1083 nm emission in 5° latitude zones have been used. Three types of spectral analysis have been tested: the Welch method, the multitaper method, and the Schuster periodogram method. The first two methods have been chosen for the analysis of observing time intervals 26 and 3 years in length. The Schuster periodogram method is more suitable for the sliding spectral analysis in a 1-year-long temporal window with a shift by half a year. The chosen methods for analyzing the power spectra allow one to obtain the spectral densities, the powers of significant peaks in them and the corresponding periods, the total powers in the specified intervals of periods and to estimate the significance of the peaks found and the intervals in which the true periods corresponding to the peaks can be located.