Satellite altimetry reveals spatially nonlocal kinetic energy cascade in the global ocean.

Abstract

The transfer of kinetic energy (KE) across spatial scales has traditionally been viewed as a process where KE lost or gained by larger-scale motions is balanced by smaller-scale motions within the same region. Using satellite altimetry and a coarse-graining framework, we show that the global surface KE cascade is predominantly spatially nonlocal: Energy lost or gained by larger scales can be redistributed and transported to or from other regions rather than solely feeding local smaller scales. In eddy-rich regions, such as the Kuroshio Extension and Southern Ocean, this nonlocality is pronounced and associated with non-negligible residual KE. This nonlocal behavior is also evident in ocean models, revealing that spatially nonlocal KE transfer is a fundamental and robust feature of global ocean dynamics.