Spurious Transitions in Convective Regime Due to Viscosity Clipping: Ramifications for Modeling Planetary Secular Cooling
Bibliographic record
Abstract
Abstract The thermal evolution of a solid planet is governed by mantle convection and therefore the dependence of viscosity on temperature. In this study, over a span of five billion years, we investigate the effect of viscosity clipping (i.e., limiting the maximum value of the viscosity) on the thermal evolution of lunar‐sized initially hot bodies featuring decaying internal heat sources. Models with a decreasing viscosity contrast resulting from limiting the maximum viscosity to 105.5 times the initial viscosity at the core‐mantle boundary were first examined. At times determined by the initial internal heating rate, rapid cooling sets in as a result of a convective regime change from stagnant‐lid to mobile‐lid convection, followed by gradual cooling to a weakly convecting and eventually nearly conductive state. Subsequently, we employ a dynamic clipping viscosity of 105.5 times the viscosity at the core‐mantle boundary, throughout the planet's evolution. In this case, stagnant‐lid convection is the only convective regime observed. Finally, convection with an initially large viscosity contrast (1010) is modeled in both 2‐D and 3‐D spherical geometry, and we find strong agreement in the thermal evolution when compared with the dynamic clipping model. Our findings show that convective regime changes due to secular cooling can occur due to implementing a fixed viscosity contrast that becomes subcritical with respect to obtaining a stagnant lid. To avoid spurious convective regime changes, the specification of a dynamic clipping viscosity can be used to emulate much higher viscosity contrasts.
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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) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".