Lagrangian studies of oxygen variability in the North Atlantic Ocean
Bibliographic record
Abstract
During 1997-2000, our research group participated in a major field study to determine the absolute circulation of the Subpolar North Atlantic. We successfully tracked 50 isopycnal RAFOS floats which measured pressure, temperature, and dissolved oxygen. The floats were ballasted for the 27.5 σ &thetas; density surface, which is found in the lower subtropical thermocline waters of the North Atlantic. A comparison of our field results to historical hydrography for the region shows that the oxygen sensors provided an accuracy of about 5% over periods exceeding one year. One of our goals was to understand the conspicuous difference between the hydrographically measured temperature and oxygen fields in the Subpolar North Atlantic. To accomplish this goal, we have developed a horizontal, constant-density, advection-diffusion model that is based upon (1) RAFOS float observations of the absolute circulation and (2) climatological fields of temperature, salinity, and oxygen. A key feature of the model is the time-dependent ventilation in the Irminger Basin and Labrador Sea. We represent ventilation by imposing water-transformation rates typical for the region. The model adequately predicts the observed temperature, salinity, and oxygen fields when ventilated waters become saltier at a rate of 0.2 psu/yr, warmed by a corresponding amount to preserve constant density, and instantly saturated in oxygen. Another goal was to use RAFOS floats to study in situ biological processes simultaneous with the physical context in which they occur. To accomplish this goal, we have developed a vertical, one-dimensional model that is based upon (1) RAFOS float observations of the near-surface waters of the northern North Atlantic and (2) satellite-derived observations of meteorological and biological fluxes of heat, salt, momentum, and oxygen. We find that the model accurately reproduces the physical context: the model predicts the float observations of temperature to within 1°C for an entire year. The model also reproduces the observed oxygen variability: (1) a ∼3% oxygen supersaturation in the wintertime mixed layer, driven by an air-sea gas flux, and (2) a drop from 105% saturation to 92% saturation over a four month period as the float subducted below the mixed layer, driven by net community respiration at depth.
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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 | 0.000 | 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".