Revisiting Mesoscale Eddy Zonal Propagation: Addressing the Long-Wave
Approximation Limitation for Improved Global Estimates
Abstract
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.