Robust intensification of global ocean Eddy Kinetic Energy from three decades of satellite altimetry observations

TL;DR

This study analyzes 30 years of satellite data to reveal significant global increases in ocean mesoscale activity, especially in key regions like the Gulf Stream, impacting climate system understanding.

Contribution

It provides the first comprehensive quantification of long-term EKE trends from satellite altimetry, highlighting regional intensification and implications for climate models.

Findings

Global EKE increased by 1-3% per decade.

Significant EKE increases in the Kuroshio Extension (~50%) and Gulf Stream (~20%).

Observed trends challenge current climate models' small-scale process representation.

Abstract

Ocean mesoscale variability, a key component of the climate system, influences ocean circulation and heat, gas, carbon and nutrient distribution. Trends on Eddy Kinetic Energy (EKE), a metric measuring its intensity, are investigated using two products constructed from 30 years of altimetric observations. Statistically significant positive trends in globally-averaged EKE reveal a strengthening of 1-3% per decade. Regions of intense mesoscale activity become more energetic than other areas. Robust positive EKE trends are observed in the Kuroshio Extension and the Gulf Stream, with remarkable EKE increases of ~50% and ~20%, respectively, over the last decade. Our study opens a new question into how the observed Gulf Stream strengthening impacts the AMOC, and challenges existing climate models emphasizing the necessity for improved small-scale ocean process representation.