Transport of substantial 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 %–15 % of the tropospheric ozone sources. However, the chances of intruded stratospheric ozone reaching the surface are low. Here, we report an event of a strong surface ozone surge of stratospheric origin in the North China Plain (NCP, 34–40∘ N, 114–121∘ E) during the night of 31 July 2021. The hourly measurements reveal surface ozone concentrations of up to 80–90 ppbv at several cities over the NCP from 23:00 LST (Local Standard time, = UTC +8 h) on 31 July to 06:00 LST on 1 August 2021. The ozone enhancement was 40–50 ppbv higher than the corresponding monthly mean. A high-frequency surface measurement indicates that this ozone surge occurred abruptly, with an increase reaching 40–50 ppbv within 10 min. A concurrent decline in surface carbon monoxide (CO) concentrations suggests that this surface ozone surge might have resulted from the downward transport of a stratospheric ozone-rich and CO-poor air mass. This is further confirmed by the vertical evolutions of humidity and ozone profiles based on radiosonde and satellite data respectively. Such an event of stratospheric impact on surface ozone is rarely documented in view of its magnitude, coverage, and duration. We find that this surface ozone surge was induced by a combined effect of dying Typhoon In-fa and shallow local mesoscale convective systems (MCSs) that facilitated transport of stratospheric ozone to the surface. This finding is based on analysis of meteorological reanalysis and radiosonde data, combined with high-resolution Weather Research and Forecasting (WRF) simulation and backward trajectory analysis using the FLEXible PARTicle (FLEXPART) particle dispersion model. Although Typhoon In-fa on the synoptic scale was at its dissipation stage when it passed through the NCP, it could still bring down a stratospheric dry and ozone-rich air mass. As a result, the stratospheric air mass descended to the middle-to-low troposphere over the NCP before the MCSs formed. With the pre-existing stratospheric air mass, the convective downdrafts of the MCSs facilitated the final descent of stratospheric air mass to the surface. Significant surface ozone enhancement occurred in the convective downdraft regions during the development and propagation of the MCSs. This study underscores the substantial roles of weak convection in transporting stratospheric ozone to the lower troposphere and even to the surface, which has important implications for air quality and climate change.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.003 | 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 teacher head, 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".