The Solar Oscillations Spectrum and the Solar Cycle

Abstract

During the summer seasons of the years 1977 to 1985 daily velocity measurements of solar global oscillations have been obtained using a resonant scattering spectrometer. After calculating the power spectra of the daily residuals, the mean for each season is found. Several discrete frequency intervals are defined in the spectrum which yield information on the characteristics of the oscillations and noise levels. The mean power in these intervals and the cut-off frequency of the p-mode spectrum, determined for each year, are correlated with the solar activity cycle. Furthermore, several series of 13 contiguous days for each year are analyzed. The frequency and amplitude of the p modes of 1 ≤ 3 and 11 ≤ n ≤ 33 are determined and their average for these years is found. The frequency differences between modes of the same degree 1 and between neighbouring modes are found. Their variation over the years is compared with the solar activity cycle.