Coping with the concurrent heatwaves and ozone extremes in China under a warming climate

Science Bulletin, Год журнала: 2024, Номер 69(18), С. 2938 - 2947

Опубликована: Май 25, 2024

Язык: Английский

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Evolution of Ozone Pollution in China: What Track Will It Follow?

Environmental Science & Technology, Год журнала: 2022, Номер 57(1), С. 109 - 117

Опубликована: Дек. 28, 2022

Increasing surface ozone (O3) concentrations has emerged as a key air pollution problem in many urban regions worldwide the last decade. A longstanding major issue tackling is identification of O3 formation regime and its sensitivity to precursor emissions. In this work, we propose new transformed empirical kinetic modeling approach (EKMA) diagnose using regulatory NO2 observation datasets, which are easily accessible. We demonstrate that mapping monitored data on modeled regional O3–NO2 relationship diagram can illustrate historical evolution precursors region. By applying approach, show for most China, currently associated with volatile organic compound (VOC)-limited regime, located within zone daytime-produced (DPO3) an 8h-NO2 concentration ratio below 8.3 ([DPO3]/[8h-NO2] ≤ 8.3). The production controlling effects VOCs NOx different cities China were compared according their routes. developed herein may have broad application potential evaluating efficiency controls further mitigating pollution, particular, where comprehensive photochemical studies unavailable.

Язык: Английский

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Field Quantification of Hydroxyl Radicals by Flow-Injection Chemiluminescence Analysis with a Portable Device

Environmental Science & Technology, Год журнала: 2024, Номер 58(6), С. 2808 - 2816

Опубликована: Янв. 16, 2024

Hydroxyl radical (•OH) is a powerful oxidant abundantly found in nature and plays central role numerous environmental processes. On-site detection of •OH highly desirable for real-time assessments •OH-centered processes yet restrained by lack an analysis system suitable field applications. Here, we report the development flow-injection chemiluminescence (FIA-CL) continuous •OH. The based on reaction with phthalhydrazide to generate 5-hydroxy-2,3-dihydro-1,4-phthalazinedione, which emits (CL) when oxidatively activated H2O2 Cu3+. FIA-CL was successfully validated using Fenton as standard source. Unlike traditional absorbance- or fluorescence-based methods, CL could minimize interference from medium (e.g., organic matter), therefore attaining sensitive (limits quantification = 0.035 0.12 nM, respectively). broad applications were illustrated on-site 24 h produced photochemical lake water air, where temporal variations productions (1.0–12.2 nM 1.5–37.1 × 107 cm–3 air) agreed well sunlight photon flux. Further, enabled oxidation reduced substances triggered tidal fluctuations coastal soils. superior analytical capability opens new opportunities monitoring dynamics under conditions.

Язык: Английский

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Tropical cyclone-related heatwave episodes in the Greater Bay Area, China: Synoptic patterns and urban-rural disparities

Weather and Climate Extremes, Год журнала: 2024, Номер 44, С. 100656 - 100656

Опубликована: Март 1, 2024

Tropical cyclone (TC) peripheral downdrafts and urbanization can promote extreme heatwave (HW) events in the Greater Bay Area (GBA), a highly urbanized coastal area China. However, roles of synoptic patterns HW remain unclear, particularly for joint occurrences tropical (TC-HW) extremes. Here, we identify three closely related to TC-HW events, namely: northeastern Taiwan TC pattern (P4), southeastern (P6), eastern Taiwan-Philippine Sea (P7), as these could enhance HWs through strong downdrafts, solar radiation, low humidity, thereby favoring maintenance events. Among patterns, P6 is most conducive occurrence compound GBA. Moreover, urban-rural temperature disparities under are unique than those on days without i.e., daily maximum at rural suburban stations higher that urban stations. This feature opposite heat island mainly attributed subsidence warming induced by TCs Foehn effects. These results indicate spatial distribution substantially modulated TCs, which meaningful understanding features underlying mechanism adapting their impacts.

Язык: Английский

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Spatial disparities of ozone pollution in the Sichuan Basin spurred by extreme, hot weather

Atmospheric chemistry and physics, Год журнала: 2024, Номер 24(5), С. 3029 - 3042

Опубликована: Март 8, 2024

Abstract. Under the influence of climate change, increasing occurrence extreme weather events, such as heatwaves, has led to an enhanced frequency ozone (O3) pollution issues. In August 2022, Sichuan Basin (SCB), a typical large-scale geographical terrain located in southwestern China, experienced most severe heatwave last 20 years. The substantial disparities O3 levels across region. Here, by integrating observations, machine learning, and numerical simulations, we aim understand diverse formation mechanisms two megacities, Chengdu (western location) Chongqing (eastern location). Observational data showed that consecutive 17 d period exceedance, contrast Chongqing, where concentrations remained below standard. Meteorological precursor factors were assessed, highlighting high temperatures, intense solar radiation, overnight accumulative pollutants key contributors concentrations. interplay isoprene, temperature, O3, alongside observation-based box model MEGAN underscored significant role intensified biogenic volatile organic compounds (BVOCs) formation. Interestingly, exhibited nearly double BVOC emissions Chengdu, yet contributed less This discrepancy was addressed through CMAQ-DDM (Decoupled Direct Method) simulations satellite diagnosis investigating O3–NOx–VOC sensitivity. Notably, displayed VOC-driven sensitivity, while transitional regime. Moreover, regional transport also played pivotal spatial divergence pollution. Cross-regional predominantly influenced (contributing ∼ 80 %), whereas mainly affected within basin. local accumulated gave rise atmospheric oxidizing capacity, resulting photochemical contribution (49.9 ppbv h−1) Chengdu. comparison difference provides insights into complex meteorology, natural emissions, anthropogenic sources during guiding necessity targeted control measures on scales.

Язык: Английский

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The Influence of Synoptic Weather Patterns on Spatiotemporal Characteristics of Ozone Pollution Across Pearl River Delta of Southern China

Journal of Geophysical Research Atmospheres, Год журнала: 2022, Номер 127(21)

Опубликована: Окт. 29, 2022

Abstract Tropospheric ozone (O 3 ) pollution is becoming the primary obstacle to improvement of air quality in China, especially Pearl River Delta (PRD) region. Because O episodes are closely related synoptic weather patterns (SWPs), historical (from 2006 2019) were classified according SWPs using Lamb‐Jenkinson method. Monitoring network and reanalysis data, emission inventories, satellite retrievals used investigate spatiotemporal characteristics influences pollution. It was found that easterly (P_E), anticyclone (P_A), typhoon‐related (P_NE) accounted for 75% all episodes. In PRD, formation mechanism showed clear differences under different SWPs, which affected by local emissions P_A, whereas regional transmission dominated P_E P_NE. The peak concentration strongly associated with temperature, solar radiation, shifting sea‐land breeze. A delayed shift land sea breeze caused often appear late afternoon. Finally, stepwise regression explain individual meteorological parameters contributing formation. P_NE increases temperature while P_A mainly increase overnight accumulation . This study advances our knowledge provides scientific support effective control.

Язык: Английский

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Co‐Occurrence of Surface O₃, PM_2.5 Pollution, and Tropical Cyclones in China

Journal of Geophysical Research Atmospheres, Год журнала: 2022, Номер 127(14)

Опубликована: Июль 6, 2022

Abstract Extreme weather events are on the rise against backdrop of climate change. Impact tropical cyclone (TC) system, one extreme events, air pollution remain poorly understood. A total 103 recorded TCs (tropical storms and stronger) together with surface quality data collected from over 2000 observational sites in mainland China 2014–2020 were utilized to examine co‐occurrence TC continental ozone (O 3 ) fine particulate matters (PM 2.5 pollution. exhibit cleaning effects PM within its coverage (typically ∼650 km), but enhance O an extended region. The frequencies greater than 30% for any two co‐occurring ∼8% + . We observed superregional trans‐boundary transportation pollutants driven by TC, led ubiquitous spatial offsets temporal lags , which often inconsistent traditional mechanisms such as accelerated chemical reactions formation. tends occur 1∼2 days after moved west. In contrast, usually 4–12 hr following a day most regions except southeast China. Such vary paths TCs. Composite analysis shows that temperature, wind field large pressure systems key factors formation periphery. Our results have implications understanding interactions between pollution, particularly coastal areas where there recurring

Язык: Английский

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Distinct seasonality in vertical variations of tropospheric ozone over coastal regions of southern China

The Science of The Total Environment, Год журнала: 2023, Номер 874, С. 162423 - 162423

Опубликована: Март 1, 2023

The surface ozone pollution is strongly coupled with variations above the ground. Using sufficient airborne profiles during 2012–2018, this study reveals tropospheric distributions over four cities located in coastal regions of southern China. 7-year mean consistently show a double-maxima profile, local maximum at 1 km altitude and other middle-to-upper troposphere. Seasonally, springtime larger than annual throughout troposphere, while summer high leading to largest vertical among seasons. Ozone troposphere lower autumn spring summer. winter characterized minimum low values least We untangle causes for these complicated using GEOS-Chem model. China partitioned into locally produced ozone, regionally transported native imported from outside (foreign ozone) natural stratospheric ozone. results suggest that abundance due enhanced import foreign intensified regional transport processes In summer, production strengthened upward air motions, such becomes weaker leaving winter, intensive westerly jets promote again but are sharply reduced, resulting near surface. This provides new insights significance on prevention strategy.

Язык: Английский

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Co‐Occurring Extremes of Fine Particulate Matter (PM_2.5) and Ground‐Level Ozone in the Summer of Southern China

Geophysical Research Letters, Год журнала: 2024, Номер 51(2)

Опубликована: Янв. 19, 2024

Abstract Concurrent pollution of fine particulate matter (PM 2.5 ) and ozone has been increasingly reported in China recently. Here, we further confirm widespread co‐occurring summertime PM ‐ozone extremes southern China. Annual‐average frequency co‐occurrence is above 50% from 2015 to 2022, especially Pearl River Delta region (72 ± 12%). The spatial extent (city numbers) temporal persistence (co‐occurrence days) for cities with >50% increase at a rate two cities/year 14 days/year, respectively. We identify typical synoptic conditions (e.g., typhoon periphery circulation, West Pacific subtropical high) conducive co‐occurrence. Through combining multi‐source data, Random Forest model well predicts identifies common precursors volatile organic compounds) as important variables. Finally, postulate linked secondary generation shared precursors. Our results suggest high potentials control strategies on mitigate concurrent pollution.

Язык: Английский

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Extreme weather exacerbates ozone pollution in the Pearl River Delta, China: role of natural processes

Atmospheric chemistry and physics, Год журнала: 2024, Номер 24(2), С. 1559 - 1570

Опубликована: Фев. 1, 2024

Abstract. Ozone (O3) pollution research and management in China have mainly focused on anthropogenic emissions, while the importance of natural processes is often overlooked. With increasing frequency extreme weather events, role exacerbating O3 gaining attention. In September 2022, Pearl River Delta (PRD) southern experienced an extended period (25 d) regional exceedances high temperatures (second highest over last 2 decades) due to conditions influenced by subtropical typhoon peripheries. Employing integrated approach involving field measurements, machine learning numerical model simulations, we investigated impact weather-induced considering meteorological factors, chemistry pathways atmospheric transport. The hot intensified emission biogenic volatile organic compounds (BVOCs) ∼10 %. Isoprene formaldehyde accounted for 47 % situ production, underscoring predominant BVOC emissions processes. chemical pathway isoprene contributing formation was further explored, with production more attributable degradation early generation oxidation products (contributed 64.5 %) than direct itself 35.5 %). Besides, it found that significantly promoted photochemical reactions, factors additional 10.8 ppb levels compared normal conditions. Temperature identified as dominant factor. Furthermore, nearing landfall enhanced cross-regional transport from northern through stratosphere–troposphere exchange (STE). CAM-Chem simulations revealed STE-induced PRD surface could reach a maximum ∼8 ppb, highlighting non-negligible STE. This study highlights exacerbated events provides valuable insights into control under global warming.

Язык: Английский

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