Mesoscale eddies play a crucial role in the transport and mixing processes of the global ocean. Their zonal propagation has routinely been predicted using the theoretical phase speed of long baroclinic Rossby waves. However, this long-wave speed is known to be too fast to quantify the eddy zonal propagation equatorward of ~35 latitudes. To address this fundamental issue, this study takes the local eddy wavelengths into account for estimating the eddy zonal propagation globally, whose accuracy is then significantly improved, particularly across mid- to low-latitudes. This improvement hinges upon the observation that mesoscale eddies across mid- to low-latitudes have length scales comparable to the local deformation scales and do not satisfy the long-wave approximation. Additionally, the observed eddy radii from satellite altimetry can be readily used to estimate the local eddy wavelengths. These findings have significant implications for long-range mesoscale eddy propagation behaviors and eddy-driven mixing throughout the global ocean.
