Synoptic tracer gradients in the upper troposphere over central Canada during the Stratosphere‐Troposphere Experiments by Aircraft Measurements 1998 summer campaign
Bibliographic record
Abstract
During the July 1998 Stratosphere‐Troposphere Experiments by Aircraft Measurements (STREAM) intensive campaign, eight measurement flights were conducted from Timmins airport (Ontario, Canada, 48.2°N, 79.3°W). In situ measurements of ozone, carbon monoxide, carbon dioxide, and nonmethane hydrocarbons, as well as three‐dimensional back trajectories based on European Centre for Medium‐Range Weather Forecasts wind field analyses, are used to characterize upper tropospheric air masses with respect to their origin. In the upper troposphere between 8 km and the local tropospause, about 40% of the air masses originated from the subtropics/tropics south of 30°N, about 50% originated from midlatitudes (between 30° and 50°N), and 12% originated from the polar region north of 50°N. In general, highest trace gas levels were observed in air masses originating from midlatitudes (e.g., CO, 107 ± 25 ppbv; ethane, 983 ± 385 pptv; acetylene, 119 ± 43 pptv), with the exception of CO, which had highest mixing ratios (121 ± 11 ppbv) in air masses of polar origin. The lowest concentrations were generally observed in air masses of (sub)tropical origin (e.g., CO, 64 ± 2 ppbv; ethane, 424 ± 86 pptv; acetylene, 39 ± 14 pptv). For CO and most of the alkanes a significant positive latitudinal gradient was observed, while CO 2 and CH 3 Cl exhibited an inverse gradient with lowest mixing ratios at high northern latitudes. This reflects the different source and sink distributions of the investigated species. Ozone mixing ratios significantly increased in the upper troposphere above 8 km altitude, at least partially because of stratosphere‐troposphere exchange. Approximately 10% of the upper tropospheric air was directly influenced by recent cross‐tropopause exchange. A case study indicates that the convergence of air masses of different origin along a cold front creates sharp gradients not only in temperature and humidity but also in trace gas concentrations. It is shown that these mesoscale gradients result from the organized flows of tropical, arctic, and stratospheric air masses.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.002 |
| Insufficient payload (model declined to judge) | 0.009 | 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 teacher head, 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".