Intensification of Oceanic Inverse Energy Cascade Under Global Warming

TL;DR

This study reveals a significant intensification of the oceanic inverse energy cascade over 24 years, driven by climate-related changes, which impacts ocean circulation and climate variability.

Contribution

It provides the first comprehensive analysis of how the oceanic inverse energy cascade has intensified globally under climate warming conditions.

Findings

Inverse KE cascade increased by 1-2% per decade.

Intensification occurs in both energetic and quiescent regions.

Multiple factors, including stratification and shear, contribute to this change.

Abstract

Kinetic energy (KE) cascade in the turbulent ocean is pivotal in connecting diverse scales of oceanic motions, redistributing energy, and influencing ocean circulation and climate variability. However, its response to global warming remains poorly understood. Using a 24-year satellite altimetry dataset, we identify a pronounced intensification of inverse geostrophic kinetic energy cascade at the sea surface across most ocean regions during 1994-2017, with cascade amplitude increasing by 1% to 2% per decade. This intensification occurs not only in energetic regions but also in expansive quiescent areas. Contributing factors to this intensification of geostrophic KE cascade include enhanced vertical shear of horizontal velocity, deepened mixed layer, strengthened stratification, weakened eddy killing as well as changes in the KE budget. The dominant factors vary across regions. Our findings offer new insights into the ocean's response to global warming and improve understanding of feedback mechanisms for ocean circulation changes.