Trend analysis of stratospheric BrO using ground-based UV-visible and SCIAMACHY limb observations at 60°N, 44°N, 28°N, and 45°S
Bibliographic record
Abstract
Recently, we have published a trend analysis of stratospheric bromine monoxide (BrO) columns derived from ground-based zenith-sky UV-visible observations made from 1995 to 2005 at the NDACC (Network for the Detection of Atmospheric Composition Change) stations of Harestua (60◦N, 11◦E) and Lauder (45◦S, 170◦E). The time series of stratospheric BrO vertical column densities have been fitted using a statistical model including a linear trend and seasonal components represented by polyharmonic functions. The inclusion of such functions in the model enables to fit the strong seasonality of BrO in the stratosphere. At both stations, the polyharmonic fit gives a positive trend of +2.5%/year for the 1995-2001 period, while a negative trend of -1%/year is found after 2001. Given the mean age of air over Harestua and Lauder, the decline of BrO in the stratosphere after 2001 is consistent with the reported decline of long-lived bromine source gases observed since the second half of 1998. This study provided therefore the first clear evidence for a decline of the stratospheric bromine loading in response to the Montreal Protocol limiting the production of brominated and chlorinated source gases.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| 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) | 0.001 | 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 teacher head, 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".