Anthropogenic Carbon Dynamics: Concentrations, Transports, and Trends in the Western North Atlantic Subtropical Gyre
Bibliographic record
Abstract
Abstract The ocean acts as a major carbon sink, absorbing anthropogenic CO 2 and mitigating climate change. The North Atlantic Ocean, particularly the western North Atlantic Subtropical Gyre (NASG), plays a crucial role in this process, yet the mechanisms governing the transport of anthropogenic carbon (C anth ) remain incompletely understood. In this study, we quantify C anth transport across the western NASG using hydrographic observations from repeat meridional sections (A20 and A22) and an inverse box model approach. We show that C anth transport has increased over the past four decades, primarily in surface and intermediate layers, driven by rising atmospheric CO 2 concentrations rather than significant changes in mass transport. The strongest C anth transport occurs in the Subtropical Underwater (STUW) and Subtropical Mode Water (STMW) layers, following the circulation patterns of the Gulf Stream (GS) and its recirculation. While deep and bottom layers, such as Labrador Sea Water, Iceland‐Scotland Overflow Water, and Denmark Strait Overflow Water, exhibit weaker and more variable transport, the overall trend reflects increasing C anth sequestration across the region. Long‐term atmospheric CO 2 trends from four global monitoring stations are compared with C anth levels in the western NASG, showing that both have steadily increased since 1970. Slight variations in these trends imply that factors such as ocean circulation, temperature fluctuations, and water mass dynamics could affect the region's efficiency in CO 2 uptake.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".