Stability of large-scale oceanic flows and the importance of non-local effects
Bibliographic record
Abstract
My thesis covers two general circulation problems that involve the stability of largescale oceanic flows and the importance of non-local effects.The first problem examines the stability of meridional boundary currents, which are found on both sides of most ocean basins because of the presence of continents.A linear stability analysis of a meridional boundary current on the beta-plane is performed using a quasi-geostrophic model in order to determine the existence of radiating instabilities, a type of instability that propagates energy away from its origin region by exciting Rossby waves and can thus act as a source of eddy energy for the ocean interior.It is found that radiating instabilities are commonly found in both eastern and western boundary currents.However, there are some significant differences that make eastern boundary currents more interesting from a radiation point of view.They possess a larger number of radiating modes, characterized by horizontal wavenumbers which would make them appear like zonal jets as they propagate into the ocean interior.The second problem examines the circulation in a nonlinear thermally-forced twolayer quasi-geostrophic ocean.The only driving force for the circulation in the model is a cross-isopycnal flux parameterized as interface relaxation.This forcing is similar to the radiative damping used commonly in atmospheric models, except that it is applied to the ocean circulation in a closed basin and is meant to represent the large-scale thermal forcing acting on the oceans.It is found that in the strongly nonlinear regime a substantial, not directly thermally-driven barotropic circulation is generated.Its variability in the limit of weak bottom drag is dominated by highfrequency barotropic basin modes.It is demonstrated that the excitation of basin normal modes has significant consequences for the mean state of the system and its variability, conclusions that are likely to apply for any other system whose variability is dominated by basin modes, no matter the forcing.A linear stability analysis performed on a wind-and a thermally-forced double-gyre circulation reveals that under certain conditions the basin modes can arise from local instabilities of the flow.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".