Intense Downwelling and Diffuse Upwelling in a Nonlinear Ekman Layer
Bibliographic record
Abstract
It has long been appreciated that Ekman transport and pumping velocities are modified through interactions with underlying geostrophic currents. Nonlinearity involving interaction of the Ekman flow with itself is, however, typically neglected. This nonlinearity occurs when the Rossby number based on the Ekman velocity and horizontal length scale approaches order one values. Such values are common, for example, in the ice-ocean stress field across sharp gradients such as leads in the sea ice cover. Recent work has shown strong asymmetry in the pumping velocities, with cyclonic forcing producing diffuse upwelling and anticyclonic forcing producing sharp downwelling fronts. To better understand this dynamics, we consider the steady response to a simple specified prescription of the stress. In the (x-z) plane perpendicular to the stress, dynamics are described by the 2-D Navier-Stokes equation, with a forcing term dependent on vertical shear of velocity in the y-hat direction, specified by a pressureless momentum equation. An expansion in an Ekman-velocity based Rossby number is used to solve the system and to better understand the asymmetry. Interactions with stratification and underlying geostrophic currents are also considered, and examples of where these effects might be important are given.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".