{"paper":{"title":"Drag-Controlled Regime Transitions in the Eddy Saturation Mechanism of the Antarctic Circumpolar Current","license":"http://creativecommons.org/licenses/by/4.0/","headline":"Below a wind-to-friction threshold, Antarctic Circumpolar Current eddy saturation uses both meander and diffusivity adjustments; above it, only meanders suffice.","cross_cats":["physics.flu-dyn"],"primary_cat":"physics.ao-ph","authors_text":"Atsushi Kubokawa, Takuro Matsuta, Yuki Tanaka","submitted_at":"2026-05-12T12:09:16Z","abstract_excerpt":"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 saturat"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"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.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"The idealized reentrant channel model captures the essential ACC dynamics, including the existence and sharpness of a drag-controlled threshold, without requiring additional real-world complexities such as variable stratification or unresolved topographic interactions.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Drag strength sets a threshold that switches the dominant eddy saturation mechanism in the ACC from combined standing meander plus eddy diffusivity adjustments to standing meander adjustment alone.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Below a wind-to-friction threshold, Antarctic Circumpolar Current eddy saturation uses both meander and diffusivity adjustments; above it, only meanders suffice.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"1ba205025843bd7791ddfe6ed49c9ea9ed73f7d4df46dacd50a895ff0d655ff4"},"source":{"id":"2605.13895","kind":"arxiv","version":1},"verdict":{"id":"0dd0ed15-47e1-4d84-a423-0e810a2cbc9f","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-15T05:26:28.685090Z","strongest_claim":"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.","one_line_summary":"Drag strength sets a threshold that switches the dominant eddy saturation mechanism in the ACC from combined standing meander plus eddy diffusivity adjustments to standing meander adjustment alone.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"The idealized reentrant channel model captures the essential ACC dynamics, including the existence and sharpness of a drag-controlled threshold, without requiring additional real-world complexities such as variable stratification or unresolved topographic interactions.","pith_extraction_headline":"Below a wind-to-friction threshold, Antarctic Circumpolar Current eddy saturation uses both meander and diffusivity adjustments; above it, only meanders suffice."},"references":{"count":2,"sample":[{"doi":"10.1175/jpo-d-17-0182.1","year":2019,"title":"C., & Hogg, A","work_id":"cf1ceee6-be75-48e7-9952-68f4566e41ef","ref_index":1,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1175/jpo-d-20-0142.1","year":1994,"title":"https://doi.org/10.1175/JPO-D-20-0142.1 Large, W. G., McWilliams, J. C., & Doney, S. C. (1994). Oceanic vertical mixing: A review and a model with a nonlocal boundary layer parameterization. Reviews o","work_id":"61d27f86-a3d9-413c-9908-93c6f0e13a3f","ref_index":2,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":2,"snapshot_sha256":"5e4f375e0b3abe19ca931c4c04249623ae88c50502f9fe3acff39a80071c705d","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}