Foreign influences on tropospheric ozone over East Asia through global atmospheric transport
Bibliographic record
Abstract
Tropospheric ozone in East Asia is influenced by the transport of ozone from foreign regions around the world. However, the magnitudes and variations in such influences remain unclear. This study was performed to investigate the influences using a global chemical transport model, GEOS-Chem, through the tagged ozone and emission perturbation simulations. The results show that foreign ozone is transported to East Asia (20–60 ∘ N, 95–150 ∘ E) mainly through the middle and upper troposphere. In East Asia, the influence of foreign ozone increases rapidly with altitude. In the middle and upper troposphere, the regional mean concentrations of foreign ozone range from 32 to 65 ppbv, being 0.8–4.8 times higher than its native counterpart (11–18 ppbv). Annually, ∼60 % of foreign ozone in the East Asian middle and upper troposphere comes from North America (5–13 ppbv) and Europe (5–7 ppbv), as well as from foreign oceanic regions (9–21 ppbv). Over the East Asian tropospheric columns, foreign ozone appears most in spring when ozone concentrations in the foreign regions are high and the westerlies are strong and least in summer when the South Asian High blocks eastward foreign ozone from reaching East Asia south of 35 ∘ N. At the East Asian surface, the annual mean of foreign ozone concentrations is ∼22.2 ppbv, which is comparable to its native counterpart of ∼20.4 ppbv. In the meantime, the annual mean of anthropogenic ozone concentrations from foreign regions is ∼4.7 ppbv, half of which comes from North America (1.3 ppbv) and Europe (1.0 ppbv). Seasonally, foreign ozone concentrations at the East Asian surface are highest in winter (27.1 ppbv) and lowest in summer (16.5 ppbv). This strong seasonality is largely modulated by the East Asian monsoon (EAM) via its influence on vertical motion. The large-scale subsidence prevailing during the East Asian winter monsoon (EAWM) favours the downdraft of foreign ozone to the surface, while widespread convection in the East Asian summer monsoon (EASM) blocks such transport. Interannually, the variation in foreign ozone at the East Asian surface is found to be closely related to the intensity of the EAM. Specifically, the stronger the EAWM is in a winter, the more ozone from North America and Europe reaches the East Asian surface because of the stronger subsidence behind the East Asian trough. In summer, ozone from South and South-east Asia is reduced in strong EASM years due to weakened south-westerly monsoon winds. This study suggests substantial foreign influences on ozone at the East Asian surface and in its tropospheric columns. It also underscores the importance of the EAM in the seasonal and interannual variations in foreign influences on surface ozone in East Asia.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| 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".