In situ and Remote Sensing Observations for Understanding Nitrous Oxide in the Troposphere and Stratosphere
Bibliographic record
Abstract
Nitrous oxide (N2O) is the third most important long-lived greenhouse gas and the most important ozone depleting substance in the present day. Earth observing systems measuring N2O concentrations need to capture small magnitude changes to advance scientific understanding. Atmospheric N2O concentrations are changing due to climate-related changes in the Brewer-Dobson circulation, which is implicated in observed changes to the atmospheric lifetime of N2O. Profile measurements of long-lived trace gases from balloons can support satellite measurements and can also directly assess stratospheric circulation changes. Ground-based column measurements can also be used to probe N2O variability.The Canadian Atmospheric Laser Absorption Spectrometer Experiment Test-bed (CALASET) project goal is to develop infrared laser spectrometers with open-path multipass cells for deployment on stratospheric balloon gondolas. These instruments' in situ measurements of trace gases, including N2O and carbon dioxide (CO2), were designed to produce vertical profiles with fine vertical resolution and high precision. Ascent and descent profiles were collected during an August 2022 balloon campaign in Timmins, ON. N2O profiles from approximately 100 to 10 mbar were measured during the ascent and descent portions of the flight with a precision of 1.1 ppb. There was a significant offset between the ascent and descent mixing ratios of about 20 ppb, possibly due to changes in the multipass cell temperature. A comparison of the profiles to measurements from the Aura Microwave Limb Sounder (MLS) and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) showed good agreement, with some significant disagreement with MLS in the lower stratosphere. The observational record from the Network for the Detection of Atmospheric Composition Change (NDACC) includes long timeseries of multiple trace gas column abundances, including N2O. Previous investigation of the Toronto site showed large enhancements in N2O column abundance. The possibility that such N2O enhancements could be related to biomass burning was investigated. The uncertainty in the NDACC N2O measurements was large compared to the enhancement magnitude estimated from literature emission factor values. In both NDACC and CALASET measurements, the uncertainty in spectroscopic constants were large contributors to the overall uncertainty.
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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) | 0.002 | 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".