Influence of entrainment on the mean and seasonal variability in the Denmark Strait Overflow Water (DSOW) properties in the West Irminger Sea
Bibliographic record
Abstract
Formed by deep convection in the Nordic Seas, cold, oxygen-rich Denmark Strait Overflow Water (DSOW) is the densest water mass in the lower limb of the Atlantic Meridional Overturning Circulation (AMOC). As DSOW spreads southward from the Denmark Strait into the Irminger Sea, the overflow water entrains ambient water masses. This entrainment is critical for the transfer of climate signals and biogeochemical tracers from the surface to the deep ocean. Although the impact of entrainment on DSOW properties in the immediate vicinity of the Denmark Strait (< 100 km downstream of the sill) has been studied extensively, the entrainment dynamics contributing to DSOW transformation further downstream in the Irminger Sea and its influence on variability in DSOW properties remain unclear. Here, we use observations from BGC-Argo floats and moorings along with an idealized numerical model of entrainment mixing to investigate the dynamics contributing to the observed DSOW transformation in the western Irminger Sea. We find that DSOW experiences continual warming and deoxygenation as it spreads along the Deep Western Boundary Current in the Irminger Sea. Furthermore, novel dissolved oxygen measurements from moored instruments offshore of Cape Farewell, Greenland reveal seasonality in the oxygen content of DSOW for the first time. Numerical model simulations of supercritical entrainment dynamics predict DSOW properties offshore Cape Farewell that are cooler and more oxygenated than in the observations. This disagreement suggests that sub-critical entrainment influences DSOW transformation in the western Irminger Sea, which we test by accounting for this process in the model. Model sensitivity experiments further suggest that the observed seasonal variation in the oxygen content of DSOW likely originates from the source overflow water upstream of the Denmark Strait. Overall, this work is the first to explore the entrainment dynamics of DSOW in the western Irminger Sea and its influence on the oxygen content of the overflow water, with implications for the response of the AMOC structure and dissolved gas uptake to changes in the climate system.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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".