Transport of large stratospheric ozone to the surface by a dying typhoon and shallow convection
Bibliographic record
Abstract
Abstract. Stratospheric ozone transported to the troposphere is estimated to account for 5–10 % of the tropospheric ozone sources. However, chances for intruded stratospheric ozone to reach the surface are low. Here, we report an event of strong surface ozone surge with stratospheric origins in the North China Plain (NCP, 34° N–40° N, 114° E–121° E) at night of 31 July 2021. The hourly measurements revealed that surface ozone concentrations were up to 80–90 ppbv at several cities over the NCP from 23:00 on 31 July 1 to 6:00 on 01 August, 2021, which was 40–50 ppbv higher than the corresponding monthly mean. A high-frequency surface measurement indicates that this ozone surge occurred abruptly and reached 40–50 ppbv within ~10 minutes. A concurrent decline in surface carbon monoxide (CO) concentrations suggests that this surface ozone surge resulted from downward transport of stratospheric ozone-rich and CO-poor airmass. This is further confirmed by the vertical evolutions of humidity and ozone profiles at night, based on radiosonde and satellite data, respectively. Such an event of stratospheric impact on surface ozone is rarely documented in terms of its magnitude, covering areas, abruptness, and duration. We find that this surface ozone surge was induced by a combined effect of a dying typhoon In-fa and shallow local mesoscale convective systems (MCS) that facilitated the transport of stratospheric ozone to the surface. This finding is based on analysis of meteorological reanalysis and radiosonde data, combining with high-resolution FLEXPART-WRF modeling. (WRF: Weather Research and Forecasting, FLEXPART: Flexible Lagrangian particle dispersion model). Although the synoptic-scale typhoon In-fa was in dissipation stage when it passed through the NCP, it could still bring down stratospheric dry and ozone-rich airmass. As a result, the stratospheric airmass descended to the middle-to-low troposphere over the NCP before the MCS formed. With the pre-existed stratospheric airmass, the convective downdrafts of the MCS facilitated the final descending of stratospheric airmass to the surface. Significant surface ozone enhancement occurred in the convective downdraft regions during the development and propagation of the MCS. This study underscores the non-negligible roles of dying typhoons and shallow convection in the transport of stratospheric ozone to the troposphere and even the surface, which have important implications for air quality, tropospheric ozone budget, and climate change.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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".