2026/06/02 by Michael Maalouly, Apolline Dekens, Guillaume Lapeyre +3
Earth and Planetary Sciences · #Oceanographic and Atmospheric Processes #Ocean Waves and Remote Sensing #Marine and coastal ecosystems
paper · doi:10.1175/jpo-d-25-0103.1
Abstract We investigate the properties of relative dispersion of Lagrangian particles in a global ocean simulation resolving both inertia–gravity waves (IGWs) and meso- and submesoscale (M/SM) turbulence. More specifically, we test if the dispersion laws depend on the shape of the Eulerian kinetic energy spectrum, as predicted from quasigeostrophic turbulence theory. To this end, we focus on two areas, in the Kuroshio Extension and in the Gulf Stream, for which the relative importance of IGW compared to M/SM varies in summer and winter. In winter, Lagrangian statistical indicators return a picture in overall agreement with the shape of the kinetic energy spectrum. Conversely, in summer, when submesoscales are less energetic and higher-frequency internal waves gain importance, the expected relations between dispersion properties and spectra do not seem to hold. This apparent discrepancy is explained by decomposing the flow into nearly balanced motions and IGWs and showing that the latter dominate the kinetic energy spectrum at small scales. Our results are consistent with the hypothesis that high-frequency IGWs do not impact relative dispersion, which is then controlled by the nearly balanced, mainly rotational, flow component at larger scales. These results highlight that geostrophic velocities derived from wide-swath altimeters, such as Surface Water and Ocean Topography (SWOT), may present limits when estimating surface dispersion and that current-measuring satellite missions may provide the complementary information to do so.