Competition Between Advected and Local Variability Determines Coherent Propagation of Labrador Sea Water Along the DWBC
Bibliographic record
Abstract
Abstract The Deep Western Boundary Current (DWBC) is a major conduit for the equatorward export of dense waters formed in the subpolar North Atlantic and Nordic Seas that constitute the lower limb of the Atlantic Meridional Overturning Circulation. Here, we investigate the extent to which there is coherent propagation of property anomalies along the DWBC from the Labrador Sea exit to 26.5°N. Past studies have focused on relationships between DWBC anomalies at selected sites. Here we use a hydrographic data set (EN4) that covers the time period of 1970–2020 to examine coherence continuously along the boundary current. Our findings reveal sharp differences between the upper and deep Labrador Sea Water (uLSW, dLSW). Specifically, dLSW property anomalies are highly correlated at all points downstream to the Labrador Sea exit. Furthermore, the lags that yield maximum correlations uniformly increase with distance along the boundary. uLSW, however, shows a sharp decline in coherence along the boundary such that the anomalies downstream are poorly correlated with those at the Labrador Sea exit and the lag times are not monotonic. Most of the decline in uLSW coherence occurs from the Labrador Sea exit to Flemish Cap, where local variability at uLSW densities is large. Our study sheds light on the competition between advected property variability and local property variability that impacts the identification of anomalies downstream. The uLSW and dLSW differences expressed along the DWBC are also evident offshore, consistent with past Lagrangian studies.
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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 | 0.002 |
| 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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".