GONG p-Mode Parameters Through Two Solar Cycles.

We investigate the parameters of global solar p-mode oscillations, namely damping width Γ , amplitude A , mean squared velocity 〈 v 2 〉 , energy E , and energy supply rate d E / d t , derived from two solar cycles' worth (1996 - 2018) of Global Oscillation Network Group (GONG) time series for harmonic degrees l = 0 - 150 . We correct for the effect of fill factor, apparent solar radius, and spurious jumps in the mode amplitudes. We find that the amplitude of the activity-related changes of Γ and A depends on both frequency and harmonic degree of the modes, with the largest variations of Γ for modes with 2400 µ Hz ≤ ν ≤ 3300 µ Hz and 31 ≤ l ≤ 60 with a minimum-to-maximum variation of 26.6 ± 0.3 % and of A for modes with 2400 µ Hz ≤ ν ≤ 3300 µ Hz and 61 ≤ l ≤ 100 with a minimum-to-maximum variation of 27.4 ± 0.4 % . The level of correlation between the solar radio flux F 10.7 and mode parameters also depends on mode frequency and harmonic degree. As a function of mode frequency, the mode amplitudes are found to follow an asymmetric Voigt profile with ν max = 3073.59 ± 0.18 µ Hz . From the mode parameters, we calculate physical mode quantities and average them over specific mode frequency ranges. In this way, we find that the mean squared velocities 〈 v 2 〉 and energies E of p modes are anticorrelated with the level of activity, varying by 14.7 ± 0.3 % and 18.4 ± 0.3 % , respectively, and that the mode energy supply rates show no significant correlation with activity. With this study we expand previously published results on the temporal variation of solar p-mode parameters. Our results will be helpful to future studies of the excitation and damping of p modes, i.e., the interplay between convection, magnetic field, and resonant acoustic oscillations.