Extratropical waves transport boreal wildfire emissions and drive regional air quality dynamics
Bibliographic record
Abstract
A synthesis of data and analyses identified eight separate wildfire events (five in boreal Canada and three in the western United States) that impacted the Pittsburgh Supersite, as well as Toronto, during June and July 2002. These data also revealed a larger structure in the nature of pollution episodes in Pittsburgh characterized by alternating periods of stagnation and cleansing. Stagnation resulted in significant and sustained increases in pollutant concentrations that were eventually flushed by clean air transported from Canada. Stagnation events were further characterized by decreases in wind speed, increases in ambient temperature, and enhanced atmospheric processing. Reverse trends were observed during the “clean” periods. Wildfire emissions consistently arrived immediately prior to the stagnation events and tended to be trapped and recirculated by the associated surface high pressure system, prolonging their impact. These receptor site dynamics were correlated to the structure and propagation of transient extratropical synoptic‐scale waves, which were characterized by eastward propagating transcontinental trough‐ridge‐trough configurations. Temporal patterns observed in the Pittsburgh data (a repeating sequence of long‐range transport followed by stagnation and then flushing) were in phase with alternating synoptic structures of the propagating waves. Northwesterly subsiding flow between the ridge and trough transported wildfire emissions from the injection height above the fires down into the Pittsburgh and Toronto air sheds. As the wave propagated, the surface high associated with the upper‐level ridge passed Pittsburgh, initiating a stagnation event. The cold front associated with the approaching trough flushed the stagnant air but reset the sequence of events as emissions from new wildfires were again transported behind the front. The sequence consistently repeated throughout the study period with a frequency directly correlated to the frequency of extratropical wave formation. Stagnation severity was related to the speed and maturity of the synoptic disturbances while wildfire impact severity corresponded to fire size.
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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 | 0.001 |
| Science and technology studies | 0.000 | 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".