Power spectra of magnetic fluctuations $⟨B_{\mathrm{avg}}^{+}⟩$ over three-year intervals with a frequency resolution of 10.5 nHz for GONG (left) and HMI (right) data, stacked vertically and spanning from 2007 to 2024. The crosses mark the reference frequency of 338 nHz. The right-hand-side panel for 2007−2009 contains no data because the HMI dataset starts in 2010. The bottom spectra were computed using the entire available time span for each respective dataset.