Effects of Long-Term History on Borehole Paleoclimatology
Bibliographic record
Abstract
Temperature changes at the surface of the earth propagate downward into the earth and are stored as perturbations to the subsurface equilibrium thermal regime associated with heat flow from the interior of the earth. Within the context of Borehole climatology, a methodology that has been widely used to reconstruct past ground surface temperature histories (GSTH), we examine the effect on the reconstructed GSTH arising from the changes that took place up to 120 kyrs before the present. The changes include the presence of an extended ice sheet, the duration of this cover, and the basal conditions of the ice sheet to account for the climatological interpretation of borehole temperature profiles. We choose three different sites from Canada. For each site, we have extracted 120 kyrs to present ground surface temperature time-series for a range of ice-cover histories from a data-calibrated glacial systems model for the last North American ice complex. These time-series provide a transient upper boundary condition for a 1-D subsurface heat transport model. This forcing introduces a thermal anomaly on a synthetic steady-state geothermal regime with equilibrium surface temperature of 8.0 C and geothermal gradient of 20 K km 1 under the assumption of an homogeneous subsurface. The corresponding results are sampled for depths of 600 m and 1000 m and are used to reconstruct the climateinduced subsurface anomalies. These anomaly profiles indicate that the long-term history has an effect that is visible at both depths but the effect is prominent at larger depths. For each site, we also use a series of 1000 MonteCarlo experiments where Gaussian noise with zero mean and standard deviation of 0.5 K is added to the forcing time series in order to give an estimate of the range of variability of the subsurface anomalies.
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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 | 0.003 | 0.008 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| 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".