Development, Validation, and Application of Methods for High Time-Response Measurement of Gaseous Atmospheric Chlorinated Species
Bibliographic record
Abstract
Halogenated compounds that participate in catalytic cycles in the atmosphere can influence the fate of chemicals, including ozone, methane, and volatile organic compounds (VOCs). These halogen radicals, in particular atomic chlorine (Cl), can deplete ozone and will react rapidly with VOCs. Reliable, sensitive, and widely available hydrogen chloride (HCl) measurements are important for understanding Cl initiated oxidation in many regions of the troposphere. We configured a commercial HCl cavity ring-down spectrometer (CRDS) for sampling HCl in the ambient atmosphere and developed validation techniques to characterize the measurement uncertainties. The HCl analyzer was used to make continuous HCl measurements in the polluted marine boundary layer during the Halifax Fog and Air Quality Study (HaliFAQS). Bimodal HCl features in the high irradiance days indicated two photochemical processes; (1) morning time photolysis of Cl precursors, and (2) midday formation of nitric acid followed by acid displacement onto chloride (Cl) containing aerosols. A box model used measured HCl to estimate nitryl chloride mixing ratios at sunrise and assessed the contribution of photolabile Cl precursors to radical formation. Total gaseous chlorine (TClg) measurements can illuminate unknown sources of Cl to the atmosphere. Techniques for measuring TClg have been limited to offline analysis of extracted filters and do not provide suitable temporal information on fast atmospheric process. The utility of this novel TClg measurement technique will be crucial to future estimates and assessments of chlorinated compounds and their impact on air quality, climate, and health.
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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 | 0.009 | 0.007 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".