Fast Physics and Slow Physics in the Nonlinear Dansgaard–Oeschger Relaxation Oscillation
Bibliographic record
Abstract
Abstract The Dansgaard–Oeschger (D-O) relaxation oscillation that governed glacial climate variability during marine isotope stage 3 has been accurately simulated using a high-resolution coupled climate model. Here the authors present additional detailed analyses of both the slow physics transition between warm and cold states and the fast physics transition between cold and warm states of the D-O cycle. First, the authors demonstrate that the mechanisms active during the slow transition from interstadial to stadial conditions involves the continuous flux of thick and old sea ice from the Arctic basin into the North Atlantic subpolar gyre region along the East Greenland Current. During this slow physical process, the freshwater input from sea ice melting as it moves over the surface of the warm ocean restratifies the high-latitude North Atlantic and leads to a significant reduction in the rate of North Atlantic Deep Water formation. A detailed freshwater budget and hydrography analysis is also presented to demonstrate that the D-O cycle is a low-latitude–high-latitude salt oscillator as the authors have previously argued. Second, the authors provide a more detailed analysis than previously of the fast-time-scale processes that govern the extremely rapid transition from cold stadial conditions back to the warm interstadial state. These are associated with the onset of a sub-sea ice thermohaline convective instability, which opens a massive polynya to the north of the southern boundary of the extensive North Atlantic sea ice lid that is characteristic of stadial conditions. This instability is enabled by the continuous increase of salinity above the sub-sea ice pycnocline, which eliminates the vertical salinity gradient that prevents convective destabilization of the water column under full stadial conditions. This reduction in the vertical salinity gradient beneath the sea ice lid results from the continuing northward salt transport by the North Atlantic gyre circulation once the expansion of the stadial sea ice lid has ceased. The onset of instability occurs in the Irminger basin to the south of Denmark Strait, and the authors discuss the reason for this localization of instability onset.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".