Stratospheric impact on tropospheric ozone variability and trends: 1990–2009
Bibliographic record
Abstract
Abstract. We evaluate the influence of stratospheric ozone on the interannual variability and trends in tropospheric ozone from 30–90° N between 1990 and 2009 using ozone measurements and a global chemical transport model (the Community Atmospheric Model with chemistry) with input meteorology from the National Center for Environmental Prediction. The model simulation uses constant interannual emissions. Both the model and measurements indicate that on large spatial scales stratospheric interannual ozone variability drives significant tropospheric variability and contributes to long-term tropospheric ozone trends. To diagnose the measured variability we utilized measurements from ozonesondes and the Measurements of OZone and water vapour by in-service Airbus airCraft programme (MOZAIC) north of 30° N. We identify a regionally robust 150 hPa ozone signal from measurements over Canadian, Northern European and Central European regions and at 500 hPa over Canadian, Northern European and Eastern US regions. Averaged over these regions, the 150 hPa interannual ozone variability explains 69 % of the interannual variability at 500 hPa. The simulated stratospheric signal explains 81 % of the simulated variability over these same regions. Simulated and measured ozone are significantly correlated over these regions and the simulation suggests that the ozone record over these regions is representative of the overall hemispheric 500 hPa ozone record from 30–90° N. The measured 500 hPa trends averaged over these three regions between 1990 and 2000 and 1990 and 2009 are 0.73 (±0.51) ppbv yr−1 and 0.27 (±0.19) ppbv yr−1, respectively. The simulated trends in 1990–2000 and 1990–2009 are 0.29±0.10 ppbv yr−1 and 0.13±0.05 ppbv yr−1, respectively; however, these trends are substantially larger when the model is sampled for missing data exactly as the measurements are. Simulated stratospheric ozone accounts for 79 % of the simulated 500 hPa trend between 1990 and 2000 and 100 % of the simulated trend between 1990 and 2009. Due to the importance of local meteorology and emissions at the surface it is difficult to isolate the stratospheric component of measured surface ozone variability. Overall when averaged between 30–90° N simulated surface interannual ozone trends are 0.18 ppbv yr−1 and 0.07 ppbv yr−1 between 1990 and 1999, and between 1990 and 2009, respectively. We have identified a number of surface sites where the measured interannual ozone variability is correlated with the 150 hPa ozone signal. Most notably these sites include the high mountain sites over Europe and Macehead, Ireland. Over Macehead the measured 150 hPa ozone signal explains 40 % of the interannual variability of the unfiltered measured ozone record. The simulated and measured ozone are highly correlated over Macehead. The Macehead measured and simulated unfiltered ozone trends between 1990 and 2000 are 0.28 (±0.33) and 0.17 (±0.13) ppbv yr−1 respectively; between 1990 and 2009 the measured and simulated trends are 0.18 (±0.11) and 0.08 (±0.06) ppbv yr−1, respectively. Increases in the simulated stratospheric ozone component accounts for 53 % and 75 % of the overall modeled trend for the two periods at Macehead.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| 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 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".