Mesoscale eddies are ubiquitous features in the global ocean and dominate its kinetic energy (KE) spectrum. According to geostrophic turbulence theory, once generated by instability processes, mesoscale eddies transfer their KE through an inverse cascade process toward larger scales. However, whether, and to what extent, this energy cascade has changed over time remains unclear. Here, using 30 years of satellite altimeter data, we show that the inverse KE cascade from mesoscale to large-scale motions in the surface ocean has nearly doubled, strengthening by ~30% per decade. This intensification is primarily driven by increased mesoscale eddy anisotropy and large-scale flow strain. These findings provide new insights into a global reorganization of oceanic energy, with important implications for predicting future changes of the ocean and climate system.
 

Mesoscale eddies,Inverse energy cascade,Large-scale strain,Eddy anisotropy