Total stratospheric bromine inferred from balloon-borne solar occultation bromine oxide (BrO) measurements using the new TotalBrO instrument
Bibliographic record
Abstract
Halogenated organic and inorganic compounds, in particular those containing chlorine, bromine and iodine are known to contribute to the global ozone depletion as well as directly and indirectly to climate forcing. As a result of the Montreal Protocol (1987), the chlorine and bromine loadings of the stratosphere are closely monitored, while the role of iodinated compounds to the stratospheric ozone photochemistry is still uncertain.To address the questions concerning bromine and iodine compounds, a compact solar occultation instrument (TotalBrO) has been specifically designed to measure BrO, IO (iodine oxide) and other UV/Vis absorbing gases by means of Differential Optical Absorption Spectroscopy (DOAS) from aboard a stratospheric balloon. The instrument (power consumption < 100 W) comprises of an active camera-based solar tracker (LxWxH ~ 0.40 m x 0.40 m x 0.50 m, weight ~ 12 kg) and a spectrometer unit (LxWxH ~ 0.45 m x 0.40 m x 0.40 m, weight ~ 25 kg). The spectrometer unit houses two grating spectrometers which operate in vacuum and under temperature stabilization by an ice-water bath.We discuss the performance of the TotalBrO instrument during the first two deployments on stratospheric balloons launched from Kiruna in August, 2021 and from Timmins in August, 2022 within the HEMERA program. Once the balloon gondola was azimuthally stabilized the solar tracker was able to follow the sun with a 1σ precision lower than 0.02° up to solar zenith angles (SZAs) of 95°. The spectral retrieval (of 46 spectra acquired at SZA between 84° and 90°) allowed us to infer the BrO mixing ratio above 32 km altitude. The total bromine in the middle stratosphere is inferred by accounting for the BrO/Bry partitioning derived from a photochemical model.
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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 | 0.001 | 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".