Identification of trends and interannual variability of sulfate and black carbon in the Canadian High Arctic: 1981–2007
Bibliographic record
Abstract
Trends and interannual variations of the Canadian High Arctic aerosol record at Alert, Canada (82.5°N), from 1981 to 2007 are investigated and attributed to the influences of anthropogenic emissions and long‐range transports. Sulfate and black carbon (BC) atmospheric mass concentrations declined from the mid 1980s to the late 1990s but have been relatively steady since. These tendencies are closely associated with those of the anthropogenic emissions of Eurasia (Europe and the Asian part of the former Soviet Union) and North America (United States and Canada). Interannual variations correlate with two indices derived from the 700 hPa geopotential heights. Variations in the emissions and the geopotential height indices can be used to reproduce up to 75% of the variations of the observed Arctic sulfate and BC mass concentrations. Over the 27 years of observational record, the relative contribution to sulfate and BC at Alert from Eurasia has decreased from more than 90% to about 75%. During the same time, the contributions from North American emissions has increased from less than 10% to about 25%. The increasing influence from North America was due to the faster reductions of sulfur and black carbon emissions in Eurasia during the period of these observations.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.004 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".