Horizontal propagation of near-inertial waves in mesoscale eddies

Near-inertial wave propagation in the ocean and its interaction with mesoscale eddies are significant topics in physical oceanography. This paper reviews research progress on near-inertial wave propagation, particularly its concentration in anticyclones. First, we revisit early observational and theoretical studies, highlighting the two dynamic regimes: "trapping" and "strong dispersion." We then illustrate the pioneering theoretical model by Young and Ben Jelloul (YBJ), which does not require the spatial scale separation assumption of the WKB (Wentzel-Kramers-Brillouin) approximation. Based on this model, we discuss in detail the research findings using the YBJ model, particularly the scale dependence of near-inertial wave concentration in anticyclones. YBJ model heavily relied on the WKB approximation, and, by integrating conservation laws and uncertainty relations from quantum mechanics into its framwork, provides a new framework for understanding the interaction between near-inertial waves and mesoscale features. Finally, we propose some future research directions, emphasizing the importance of studying nonlinear effects and flow field data analysis for a deeper understanding of near-inertial wave propagation.