Drag-Controlled Regime Transitions in the Eddy Saturation Mechanism of the Antarctic Circumpolar Current

Fuente: arXiv
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Autori principali: Matsuta, Takuro, Tanaka, Yuki, Kubokawa, Atsushi
Natura: Preprint
Pubblicazione: 2026
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author Matsuta, Takuro
Tanaka, Yuki
Kubokawa, Atsushi
author_facet Matsuta, Takuro
Tanaka, Yuki
Kubokawa, Atsushi
contents Eddy saturation -- the weak sensitivity of Antarctic Circumpolar Current (ACC) transport to wind stress -- is a fundamental feature of Southern Ocean dynamics, yet the processes that maintain this state remain debated. Previous studies have proposed different mechanisms, including adjustments of eddy diffusivity and standing meanders, but the conditions under which each mechanism dominates are unclear. Here we use an idealized reentrant channel model to examine how drag strength controls the eddy saturation. When the wind strength relative to friction is below a certain threshold, eddy saturation is governed by a combination of standing meander and eddy diffusivity adjustments; once the threshold is exceeded, it is governed solely by standing meander adjustment. These results suggest that changes in drag strength may account for the divergent eddy saturation mechanisms reported across studies.
format Preprint
id arxiv_https___arxiv_org_abs_2605_13895
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Drag-Controlled Regime Transitions in the Eddy Saturation Mechanism of the Antarctic Circumpolar Current
Matsuta, Takuro
Tanaka, Yuki
Kubokawa, Atsushi
Atmospheric and Oceanic Physics
Fluid Dynamics
Eddy saturation -- the weak sensitivity of Antarctic Circumpolar Current (ACC) transport to wind stress -- is a fundamental feature of Southern Ocean dynamics, yet the processes that maintain this state remain debated. Previous studies have proposed different mechanisms, including adjustments of eddy diffusivity and standing meanders, but the conditions under which each mechanism dominates are unclear. Here we use an idealized reentrant channel model to examine how drag strength controls the eddy saturation. When the wind strength relative to friction is below a certain threshold, eddy saturation is governed by a combination of standing meander and eddy diffusivity adjustments; once the threshold is exceeded, it is governed solely by standing meander adjustment. These results suggest that changes in drag strength may account for the divergent eddy saturation mechanisms reported across studies.
title Drag-Controlled Regime Transitions in the Eddy Saturation Mechanism of the Antarctic Circumpolar Current
topic Atmospheric and Oceanic Physics
Fluid Dynamics
url https://arxiv.org/abs/2605.13895