North Atlantic surface circulation during the 1990's observed with satellite‐tracked drifters
Bibliographic record
Abstract
A new compilation of Lagrangian velocity observations describes the state of the North Atlantic surface circulation during the 1990s. Gridded fields of velocity and eddy kinetic energy (EKE) are constructed from trajectories of more than 1500 15‐m drogued satellite‐tracked surface drifters in service between January 1990 and December 1999. This time period overlaps a coordinated field study of circulation and variability in the North Atlantic completed between 1996–2000 as part of the World Ocean Circulation Experiment. We describe the construction of a self‐consistent drifter climatology, present decadal‐mean quasi‐Eulerian velocity and EKE fields computed on a 1° grid, and compare these results with contemporary satellite measurements. Detailed discussion of the inferred surface circulation is focused on three regions: (1) The Gulf Stream and North Atlantic Current, (2) the Labrador Sea and subpolar gyre, and (3) the Caribbean Sea. The swiftest drifter motions were found in the equatorial region and along the tropical, subtropical, and subpolar western boundaries. The maximum instantaneous speed determined from a single (quality‐controlled and filtered) drifter observation was 273 cm s−1 in the Gulf Stream southeast of Cape Cod. The highest EKE value in the North Atlantic (2790 cm2 s−2) was found in the Gulf Stream just downstream of the New England Seamounts. Over most of the Atlantic basin, drifter‐derived EKE values were found to be O(100 cm2 s−2) higher than corresponding values derived from satellite altimetry. In the Labrador Sea a region of sharply elevated EKE appears to be geographically related to the localized ejection of drifters (and by extension, mass and kinetic energy) from the energetic West Greenland Current between 60° and 62°N. When compared to drifter measurements made in the late 1970s our results suggest (but do not statistically confirm) an enhancement and slight northward shift of the zonal Gulf Stream extension. Such a shift is consistent in sign with expectations based on observed interdecadal variations in wind stress and subtropical gyre potential energy associated with the North Atlantic Oscillation.
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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 | 0.001 |
| 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".