Numerical models of zonal flow dynamos: an application to the ice giants
Bibliographic record
Abstract
The weakly dipolar and strongly tilted magnetic fields of Uranus and Neptune are apparently generated by a dynamo process distinct from that which produces axial dipoles. We study a suite of numerical dynamos driven by convection in a rapidly rotating spherical shell and focus on cases with relatively high magnetic diffusivity. Models are presented with magnetic Prandtl number Pm = 0.1–5.0 and Rayleigh numbers between 10 and 80 times the critical Rayleigh number for convection. In the cases with high magnetic diffusivity, the fluid flow has a dominant effect over the magnetic fields, which are characteristically quadrupolar and octupolar and strongly variable in time. The dipolar component is typically weak, and strongly tilted from the axis of rotation. Most of the cases we present result in low Alfvén and Elsasser numbers, in agreement with previous studies of nondipolar dynamos. Our results suggest that the peculiar magnetic fields of Uranus and Neptune result from dynamo action driven by convectively generated, strong zonal flow in the electrolytic fluid envelope.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".