Abstract
Oceanic eddies play a profound role in mixing tracers such as heat, carbon, and nutrients, thereby regulating regional and global climate. Yet, it remains unclear how global oceanic eddy kinetic energy has evolved over the past few decades. Furthermore, coupled climate model predictions generally fail to resolve oceanic mesoscale dynamics, which could limit their accuracy in simulating future climate change. Here we show a global statistically significant increase of the eddy activity using two independent observational datasets of mesoscale variability, one directly measuring currents and the other from sea surface temperature. Regions characterized by different dynamical processes show distinct evolution in the eddy field. For example, eddy-rich regions such as boundary current extensions and the Antarctic Circumpolar Current show a significant increase of 2% and 5% per decade in eddy activity, respectively. In contrast, most of the regions of observed decrease are found in the tropical oceans. Because eddies play a fundamental role in the ocean transport of heat, momentum, and carbon, our results have far-reaching implications for ocean circulation and climate, and the modelling platforms we use to study future climate change.
Global changes in oceanic mesoscale currents over the satellite altimetry record
