Synoptic tracer gradients in the upper troposphere over central Canada during the Stratosphere-Troposphere Experiments by Aircraft Measurements 1998 summer campaign
Bibliographic record
Abstract
[1] During the July 1998 Stratosphere-Troposphere Experiments by Aircraft Measurements (STREAM) intensive campaign, eight measurement flights were conducted from Timmins airport (Ontario, Canada, 48.2degreesN, 79.3degreesW). 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 ksouth of 30degreesN, about 50% originated from midlatitudes (between 30degrees and 50degreesN), and 12% originated from the polar region north of 50degreesN. 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 CO2 and CH3Cl 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.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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".