Physical properties of the P96 ice core from Penny Ice Cap, Baffin Island, Canada, and derived climatic records
Bibliographic record
Abstract
Ice cores from nonpolar environments are being developed as valuable paleoclimatic resources. However, the recognition of a climatic signal and the development of timescales in those ice cores are both difficult due to heavy summer melting. A 177.91‐m‐long ice core (P96) was drilled in such a high‐melt area from Penny Ice Cap, Baffin Island, Canada, in 1996. The core covers the Holocene period and has pre‐Holocene ice near the bed. The purpose of this work is to investigate the physical properties of the ice and to show how these properties can be interpreted in terms of climatic signals. Visual‐stratigraphic observations and measurements of crystal size and c axis orientation were performed using conventional techniques. Melt features provided a clear picture of Holocene summer climatic changes: a warmer period prior to 2 ka, the Little Ice Age, and the modern warming trend. The crystalline structure displayed normal grain growth down to 50 m and recrystallization below this. In the 0–50 m depth interval, periodical variations in crystal size were observed and are attributed to the difference of time for which the ice was soaked in meltwater every season. These variations made it possible to develop an annual record. The c axis fabric evolution displayed a change in the ice flow pattern from divergent, above 140 m depth, to shear‐dominated flow below that. The initial fabric of superimposed ice shows a preferred c axis distribution normal to the surface. The fabric is shown to be important for reconstructing mass balance chronologies from ice cores drilled in areas of superimposed ice formation. These physical properties provide information on climatic change.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".