Present‐day variability of background ozone in the lower troposphere
Bibliographic record
Abstract
There is a substantial background of ozone (O3) present in the lower troposphere in the Northern Hemisphere that has both a stratospheric and photochemical tropospheric origin. Levels of hourly averaged O3 concentrations in the range 0.04–0.08 ppm are often measured as part of the “background O3” burden. Stratospheric processes play a significant role in defining these background O3 concentrations. In order to better understand the frequency, spatial, and temporal characteristics of this background O3 burden, we have analyzed hourly average O3 concentrations ≥0.05 and ≥0.06 ppm that were experienced during the photochemically quiescent months in the winter and spring at several rural sites across southern Canada, the northern United States, and northern Europe. Our results were mostly consistent and indicated that hourly average O3 concentrations ≥0.05 and ≥0.06 ppm occur frequently during the winter and spring months. Most occurrences were during April and May but sometimes as late as June. In some, but not all, of the cases that were studied, a plausible explanation for the higher O3 values was the presence of upper tropospheric and stratospheric air that was transported down to the surface. For purposes of making the analysis more straightforward, this study was limited to the more northerly latitudes. It might be expected that a significant contribution from natural sources is also important in producing O3 levels in the 0.05–0.06 ppm or higher range at more southerly locations where stratospheric intrusions also have an important impact on the tropospheric O3 distribution.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 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".