Left panel: R-mode dispersion relations ω = kc_r for Re = 100, 300, and 700 (red, blue, and green). The dashed black curve is the reference dispersion relation ω = kc₀. For comparison, the frequencies of each mode m observed by Löptien et al. (2018) and Liang et al. (2019) are multiplied by the factor (m + 1)/kR and plotted at abscissa kR (this simple conversion factor is derived from the dispersion relations for classical Rossby waves in spherical and local Cartesian geometries). Right panel: plot of Γ = −2kc_i for Re = 100, 300, and 700. The observed full widths at half maximum for each mode m are plotted at abscissa kR for comparison.