Mode fwhm Γ _{n, l} (upper left panel) and height H _{n, l} (upper right panel) as a function of frequency for the low-frequency p-modes l ⩽ 35 extracted from 3960 days of GONG data with the m-averaged spectrum technique. The different colors and symbols correspond to selected ranges of radial-orders n: green triangles, modes with n = 1,  2; purple stars, n = 3,  4; blue upside-down triangles, n = 5,  6; orange squares, n = 7,  8; and black dots, n ⩾ 9. The frequency resolution of the analyzed data set is indicated on the upper left-hand side plot, and the fitted background level ( B _{n, l} ) is also represented on the upper right-hand side plot (small black dots). Lower left panel: same as above, but for the mode fwhm Γ _{n, l} as a function of the mode inertia ( I), calculated from Christensen-Daslgaard's model S (Christensen-Dalsgaard et al. 1996). The frequency resolution is also indicated. Lower right panel: same as above, but for the mode asymmetry (α _{n, l} ).