Atmospheric circulation controls on precipitation isotope–climate relations in western Canada
Bibliographic record
Abstract
δ18O and δ2H time-series of monthly composite precipitation (July 1975–June 1982) for three stations located in western Canada were examined to characterize the influence of atmospheric circulation on modern isotope–climate relations in the region. Spatially coherent trends in long-term isotope and temperature anomalies were evident among the three stations, with isotope and temperature anomalies showing the strongest correlations when weighted to reflect precipitation amount. Strong correlations were also found between unweighted isotope anomalies and the Pacific–North American (PNA) index, which is a key descriptor of air-mass circulation patterns across North America. Positive δ anomalies and variable temporal δ–temperature relations having relatively shallow slopes occur during periods of intensified meridional circulation (PNA+), especially during winter. Periods of stronger zonal circulation (PNA−), in contrast, are marked by negative δ anomalies and steeper δ–temperature relations, consistent with increased distillation and deepening of the isotope shadowin the lee of the Canadian Cordillera. Significant positive correlations with pressureheight and precipitable-water anomalies located over western Canada provide additional confirmation that seasonal and interannual variability in the strength of the PNA ridge-and-trough pattern profoundly influences the isotopic evolution of moisture reaching the interior. Analogous circulation-dependent shifts in the precipitation isotope–temperature relation in western Canada also occur over much longer timescales, as inferred from isotope palaeorecords in various natural archives.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 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".