Evolution of the inorganic chlorine above Jungfraujoch and the Montreal Protocol
Bibliographic record
Abstract
The main objective of this work was to determine the inorganic chlorine budget (Cly) at northern midlatitudes, to establish its variability and to study its temporal evolution over the last fifteen years. To achieve this, we have analyzed the observational database made of IR solar spectra recorded mainly with high resolution Fourier transform spectrometers installed at the International Scientific Station of the Jungfraujoch, located in the Swiss Alps, at 3580m altitude. The analysis of ATMOS (Atmospheric Trace Molecule Spectroscopy) data allowed us to first establish that HCl and ClONO2 account for more than 93% of the total inorganic chlorine, and that the summation of their vertical column abundances is an excellent surrogate of the Cly evolution at midlatitudes. Thus, we have derived HCl and ClONO2 total column abundance time series above the Jungfraujoch to analyze their temporal evolutions. Their combination has allowed us to show that the Cly increase between 1986 and 1995 (+50%) resulted primarily from the photodissociation of long-lived chlorinated source gas, in particular the manmade chlorofluorocarbons (CFC), progressively transported to the stratosphere after their release at the Earth surface during the seventies and the eighties. The organic chlorine (CCly) decrease in the troposphere resulting from regulations adopted by the Montreal Protocol, its Amendments and Adjustments, led to a progressive stabilization of Cly in the stratosphere. However, statistical analysis and interannual variability characterizing our time series, which extend to the end of 2000, prevent any final determination of the occurrence of the Cly maximum observed here at the end of October 1996, and of its subsequent decrease. We also show that chlorine partitioning among the chlorinated reservoirs has been durably influenced by heterogeneous processes which took place on stratospheric aerosols significantly enhanced following strong volcanic eruption of Mt Pinatubo (Philippines) in June 1991. The above-mentioned topics, complementary findings resulting from the study of the evolution of inorganic fluorine in the stratosphere, as well as comparisons other observational data bases and 2D model predictions are essentially discussed in Chapter 4. Before, Chapter 1 briefly reviews physical and chemical properties of the Earth atmosphere, and processes that control the state and erosion of stratospheric ozone. Individual contributions of chlorinated source gases to the CCly budget and their temporal evolution to the latter, inventory of Cly species, phase out schedule of chemical compounds covered by the Montreal Protocol and its Amendments and Adjustments are given in Chapter 2. Chapter 3 deals with instrumentation and data processing descriptions used to produce the geophysical data sets exploited in the main chapter of this work.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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".