Slope Water Intrusions Onto Canadian Atlantic Continental Shelf During the Past 1800 Years
Bibliographic record
Abstract
Abstract Warm Slope Water (WSW), with a large Gulf Stream component, and cold Labrador Slope Water (LSW), with a strong Arctic contribution, fill deep shelf basins off southeastern Canada such as Emerald, on the Scotian Shelf, and Jordan in the Gulf of Maine. These slope waters leave their imprint in the stable isotope ratio of benthic foraminifera. We present a simple method for estimating the WSW/LSW blend using hydrographic data, the predicted equilibrium δ 18 O in benthic foraminiferal calcite, and the assumption that the dominant control on δ 18 O is temperature. Our results show that for most of the past 1800 years in deep Jordan Basin (deposition rate ∼235 cm kyr −1 ; temporal resolution ∼25 years), the slope waters were variable but generally consisted of a 60/40 mixture of LSW and WSW. About 800 years ago, LSW dominated (74% average contribution, 100% maximum contribution) Jordan and Emerald Basins for many decades, about the time that the climate was cooled by volcanic eruptions. During the Little Ice Age from ∼500 to 300 and ∼200 to ∼150 years ago, the LSW contribution was about 84% and 78%, respectively. The most extreme event, a strong trend in δ 18 O of −0.006‰ yr −1 (corresponding to ∼3.2°C increase in temperature), occurred during the Industrial Era warming beginning about 140 years ago. While hydrographic data indicate that the North Atlantic Oscillation can force short term slope water dynamics, it does not seem to be a primary driver of long‐term variability seen in the core data.
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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 | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".