Frequencies of the observed solar inertial modes (open circles; from Löptien et al. 2018; Gizon et al. 2021; Hanson et al. 2022) overplotted with the dispersion relations of the RZ Rossby modes (solid grey; given by Eq. (14)). The left and right panels correspond to modes with north–south symmetric and antisymmetric vorticity, respectively. The observed inertial modes are high-latitude (blue), Rossby (red), HFR (green), and critical-layer (magenta) modes. Observed modes whose frequencies are within 10 nHz of an RZ Rossby mode frequency with the same symmetry (|Δω|≲10 nHz) are shown with a translucent fill.