Airborne CH<sub>2</sub>O measurements over the North Atlantic during the 1997 NARE campaign: Instrument comparisons and distributions
Bibliographic record
Abstract
Airborne CH2O measurements were acquired by tunable diode laser absorption spectroscopy (TDLAS) and coil/2,4‐dinitrophenylhydrazine (CDNPH) techniques over remote regions of the North Atlantic Ocean from the surface to 8 km during the North Atlantic Regional Experiment (NARE‐97) in September of 1997. There were eight aircraft flights when both instruments were simultaneously operating, producing 665 overlapping time intervals for comparisons. A number of approaches were used in the comparisons, and indicated that on average both instruments measured identical ambient CH2O concentrations to within 0.1 ppbv, and more typically within 0.08 ppbv, over the 0 to 0.8 ppbv‐concentration range. However, significant differences, larger than the combined 2σ total uncertainty estimates, were observed in 29% of the full time‐coincident data set. The two instruments produced very similar altitude trends. Under clean background conditions in the 35° to 55°N latitude band, the median TDLAS and CDNPH CH2O concentrations were 0.399 and 0.410 ppbv for 0–2 km, 0.250 and 0.355 ppbv for 2–4 km, and 0.217 and 0.280 ppbv for 4–8 km, respectively. Elevated CH2O concentrations were observed in this study at both high altitudes (4–8 km) and in the marine boundary layer by both instruments. Thus vertical transport of CH2O and/or its precursors may provide a greater contribution to upper tropospheric HOxthan previously thought. The results of this study, which are based upon instruments employing entirely different measurement principles, calibration, and sampling approaches, not only reinforce this conclusion but also provide a high‐quality database necessary to further explore CH2O measurement‐model relationships in the clean background atmosphere.
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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) | 0.000 | 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".