Foreign influences on tropospheric ozone over East Asia through global atmospheric transport
Bibliographic record
Abstract
Abstract. Tropospheric ozone in East Asia is influenced by the transport of ozone from foreign regions around the world. However, the magnitudes and variations of such influences remain unclear. This study was performed to investigate this influence and its variations with space and time using a global chemical transport model, GEOS-Chem, for emission zero-out and tagged ozone simulations. The results show that foreign ozone varies significantly with latitude, altitude, and season in the East Asian troposphere. The transport of foreign ozone to East Asia occurs primarily through the middle and upper troposphere, where the concentration of foreign ozone (32–65 ppbv) in East Asia is 0.5–6 times higher than that of native ozone (11–18 ppbv) and has strong seasonality, being largest in spring and lowest in winter. Foreign ozone in East Asia increases rapidly with altitude. At the surface, the annual average foreign ozone concentration is ~ 22.2 ppbv, which is comparable to its native counterpart of ~ 20.4 ppbv. The annual mean concentration of anthropogenic ozone from foreign regions is ~ 4.7 ppbv at the East Asian surface, and half of it comes from North America (1.3 ppbv) and Europe (1.0 ppbv). The presence of foreign ozone at the East Asian surface is 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. In summer, the South Asian High facilitates the build-up of South Asian ozone in the East Asian upper troposphere and constrains North American, European, and African ozone to the regions north of 35° N. The interannual variations of foreign ozone at the East Asian surface have been found to be closely related to the EAM. When the EAWM is strong, North American and European ozone are enhanced at the East Asian surface, as the subsidence behind the East Asian trough becomes stronger. In strong EASM years, South and Southeast Asian ozone is reduced at the East Asian surface due to weakened south-westerly monsoon wind. This study suggests substantial foreign influences on tropospheric ozone in East Asia and underscores the importance of the EAM in the seasonal and interannual variations of 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 | 0.001 |
| 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".