Atmospheric Environment: X最新文献

{"title":"Spatial and seasonal variability of equivalent black carbon and its source contributions across Croatia","authors":"Darijo Brzoja,&nbsp;Valentino Petrić,&nbsp;Mario Lovrić,&nbsp;Nikolina Račić","doi":"10.1016/j.aeaoa.2026.100496","DOIUrl":"10.1016/j.aeaoa.2026.100496","url":null,"abstract":"<div><div>Black carbon (BC) is a major light-absorbing component of atmospheric particulate matter with well-documented effects on climate and human health, yet it remains poorly characterised across south-eastern Europe. This study presents the first systematic multi-station analysis of equivalent BC (eBC) source apportionment in Croatia, based on four years (2022–2025) of measurements from a national network of eight AE33 seven-wavelength aethalometers at five urban-background and three rural-background stations spanning continental, sub-Mediterranean, and Mediterranean environments. Fossil-fuel (eBC_ff) and biomass-burning (eBC_bb) fractions were resolved using the two-component aethalometer model. Annual mean eBC ranged from 0.28 μg m⁻³ at the cleanest rural station (Polača) to 1.92 μg m⁻³ at the most polluted urban station (Slavonski Brod), where winter biomass-burning fractions reached 73% and concentrations approached those of larger Balkan agglomerations such as Bucharest. A pronounced coastal–continental contrast was observed: continental urban stations (Slavonski Brod, Osijek, Zagreb) showed strong winter maxima dominated by residential combustion (winter eBC_bb of 62–73%), whereas coastal Mediterranean stations showed weak seasonality (eBC_bb below 34% year-round) and persistent traffic dominance. The eBC_ff component was stable and season-independent across all urban stations, identifying road traffic as a persistent, non-seasonal source, while diurnal profiles resolved traffic (twin rush-hour peaks) and evening residential-heating fingerprints. These findings establish an empirical baseline for BC in a data-sparse region of Europe and indicate that effective air quality management requires geographically differentiated strategies: prioritizing the residential energy transition in continental inland cities, where solid-fuel heating dominates the winter burden, while addressing traffic emissions in coastal urban centers.</div></div>","PeriodicalId":37150,"journal":{"name":"Atmospheric Environment: X","volume":"31 ","pages":"Article 100496"},"PeriodicalIF":3.4,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148737327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Validity of evaluation by solid particle number measurement at periodic technical inspection and in real-world conditions of diesel particulate filter","authors":"Hiroyuki Yamada,&nbsp;Kenta Hasegawa,&nbsp;Shinichi Mukai,&nbsp;Hisakazu Suzuki","doi":"10.1016/j.aeaoa.2026.100494","DOIUrl":"10.1016/j.aeaoa.2026.100494","url":null,"abstract":"<div><div>Regulated emissions in a type approval test (TAT) and a tailpipe solid particle number (SPN) concentration measurement, which has been introduced in the periodic technical inspection (PN-PTI) in some European countries, were measured for a diesel passenger car equipped with a diesel particulate filter (DPF). The correlations between SPN in TAT and the PN-PTI were good, and the European recommended limit for PN-PTI was almost equal to the regulatory limit of SPN in the TAT, suggesting the validity of evaluating exhaust performance by PN-PTI. In addition, in a real-world evaluation campaign conducted at several PTI stations in Japan, exhaust emissions from light-duty and heavy-duty vehicles under inspection were monitored by PN-PTI devices. A total of 582 DPF diesel vehicles were checked, and 18.2 % of them were found to have problems with their DPFs.</div></div>","PeriodicalId":37150,"journal":{"name":"Atmospheric Environment: X","volume":"31 ","pages":"Article 100494"},"PeriodicalIF":3.4,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148642225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ship emissions in the decarbonization era: high-resolution inventories, atmospheric impacts, and air pollution–climate co-mitigation pathways","authors":"Rongfu Xie,&nbsp;Qiao Xing,&nbsp;Qi Han,&nbsp;Zhaohui Yang,&nbsp;Yuzhen Fu,&nbsp;Xiaochen Wang,&nbsp;Xiaocong Cao,&nbsp;Aidan Xian,&nbsp;Ruipeng Wang,&nbsp;Zike Qiu,&nbsp;Yating Song,&nbsp;Wenjing Xie,&nbsp;Zongbo Chen,&nbsp;Kun Liu,&nbsp;Xiaochen Wu","doi":"10.1016/j.aeaoa.2026.100510","DOIUrl":"10.1016/j.aeaoa.2026.100510","url":null,"abstract":"<div><div>Maritime transport is a major component of global trade and an important source of atmospheric pollutants and greenhouse gases. In the decarbonization era, ship emission research is moving beyond conventional emission estimation toward integrated assessment frameworks that connect high-resolution inventories, atmospheric transformation, health and ecosystem impacts, climate forcing, and mitigation pathways. This review focuses primarily on characterizing and quantifying shipping-related primary emissions and emission inventories, which constitute the source term for atmospheric impact assessment. Ambient concentrations and environmental impacts are further governed by plume dispersion, transport, chemical transformation, and secondary pollutant formation. Using a PRISMA-style screening process, this review synthesizes recent advances in ship emission sources, inventory methodologies, spatiotemporal patterns, atmospheric impacts, and air pollution–climate co-mitigation strategies. The evolution of ship emission inventories is first reviewed, from fuel-based top-down approaches to activity-based bottom-up methods and AIS-driven high-resolution models, with emphasis on emission factors, load factors, operating-mode identification, auxiliary-engine and boiler emissions, uncertainty quantification, and multi-source validation. The review then summarizes the spatial and temporal characteristics of ship emissions, highlighting global shipping lanes, regional chokepoints, port-city interfaces, coastal corridors, straits, and island regions. Atmospheric processes and environmental impacts are further examined, including primary pollutants, secondary PM_2.5 formation, nonlinear O₃ chemistry, population exposure, health risks, atmospheric deposition, and climate forcing. The evidence indicates that ship-related impacts are shaped not only by emission magnitude, but also by chemical regimes, meteorology, receptor proximity, fuel quality, and policy context. Mitigation policies and energy-transition pathways are critically assessed, including international regulations, emission control areas, shore power, vessel speed reduction, alternative marine fuels, market-based measures, and Well-to-Wake life-cycle assessment. Overall, ship emission control is shifting from single-pollutant regulation toward integrated air pollution–climate co-mitigation. Future research should prioritize uncertainty-aware high-resolution inventories, observation-constrained emission verification, coupled air-quality–health–climate–economic assessment, AI-enhanced emission modeling, and region-specific strategies for coastal, port, strait, and island environments. An integrated data-to-impact-to-policy framework is essential for supporting cleaner, healthier, and lower-carbon maritime transport.</div></div>","PeriodicalId":37150,"journal":{"name":"Atmospheric Environment: X","volume":"31 ","pages":"Article 100510"},"PeriodicalIF":3.4,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148951537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Estimating spatio-temporal contrail coverage: Fusing satellite observations, meteorology, and air traffic flow","authors":"Rong Tang,&nbsp;Wenrui Ban,&nbsp;Kam K.H. Ng,&nbsp;Pak-Wai Chan,&nbsp;Donghai Wang","doi":"10.1016/j.aeaoa.2026.100504","DOIUrl":"10.1016/j.aeaoa.2026.100504","url":null,"abstract":"<div><div>Aircraft-induced condensation trails (contrails) are recognised as a crucial component of aviation’s climate impact. Detecting and tracking contrails in satellite imagery is vital for quantifying their coverage and radiative forcing, thereby reducing uncertainties in climate impact assessments and facilitating mitigation strategies. However, existing models are largely off-the-shelf segmentation architectures, only minimally adapted for contrail detection and lacking integration of meteorological and air traffic conditions, both of which govern contrail formation and persistence. In this study, human-labelled satellite imagery is augmented with hourly meteorological parameters and air traffic flow density as supplementary features. A dual-branch architecture is proposed, comprising a primary image branch and an auxiliary Meteo-Flow branch, enabling effective interaction and fusion of heterogeneous data sources. Experiments demonstrate consistent improvements in contrail detection across baseline models on the public human-labelled contrail dataset. Applied to GOES-16 imagery over the Continental United States (CONUS) and adjacent oceans during 16 March–15 April from 2017 to 2025, the method estimates an average contrail coverage of 0.133% and captures a 50.8% reduction during the COVID-19 period in 2020. Combined analysis with meteorology and traffic identifies contrail-intense zones and corridors and reveals pronounced diurnal cycles, providing actionable insights for data-fusion-based contrail prediction and mitigation.</div></div>","PeriodicalId":37150,"journal":{"name":"Atmospheric Environment: X","volume":"31 ","pages":"Article 100504"},"PeriodicalIF":3.4,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148951539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Natural gas dominates CH4 emissions in a Tokyo residential area based on eddy covariance measurements of CH4 and C2H6","authors":"C. Oki,&nbsp;M. Ueyama,&nbsp;Y. Terao,&nbsp;H. Sugawara,&nbsp;T. Umezawa","doi":"10.1016/j.aeaoa.2026.100506","DOIUrl":"10.1016/j.aeaoa.2026.100506","url":null,"abstract":"<div><div>Urban methane (CH₄) emissions are an important but poorly constrained component of the urban greenhouse gas budget, particularly in terms of source attribution. We conducted quasi-continuous eddy covariance measurements of CH₄ and ethane (C₂H₆) fluxes in a densely populated residential area of metropolitan Tokyo from May 2024 to December 2025 to characterize temporal variability, spatial heterogeneity, and source contributions. The strong correlation between CH₄ and C₂H₆ fluxes enabled tracer-based attribution of total CH₄ emissions to natural gas-related and biogenic sources. CH₄ emissions exhibited distinct diurnal, weekly, and seasonal patterns. Natural gas-related emissions accounted for more than 80% of the annual total, whereas biogenic emissions were minor. Wind-direction analyses revealed spatial heterogeneity associated with land use within the flux footprint. Annual CH₄ emissions were estimated at 35.2–35.7 g CH₄ m⁻² yr⁻¹. Mobile measurements corroborated the prevalence of natural gas-related sources in residential and commercial areas. These natural gas-related emissions are not explicitly represented in the local government emission inventory. These findings show that natural gas use is a dominant and spatially variable component of CH₄ emissions in urban residential environments in Japan, underscoring the need for improved observational constraints on urban greenhouse gas inventories and mitigation strategies.</div></div>","PeriodicalId":37150,"journal":{"name":"Atmospheric Environment: X","volume":"31 ","pages":"Article 100506"},"PeriodicalIF":3.4,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148951542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance and application of air quality models in Indonesia: A systematic review of progress, challenges, and future directions","authors":"Vera Surtia Bachtiar ,&nbsp;Purnawan Purnawan ,&nbsp;Assyifa Raudina ,&nbsp;Haura Rafifah Ilvi Habibah","doi":"10.1016/j.aeaoa.2026.100457","DOIUrl":"10.1016/j.aeaoa.2026.100457","url":null,"abstract":"<div><div>Air pollution remains a major environmental and health challenge in Indonesia, driven by rapid urbanization, industrial expansion, and transport emissions. This study provides a systematic review of the progress, challenges, and future directions in the performance and application of air-quality models across Indonesia from 2010 to 2024. A total of 122 peer-reviewed studies were analyzed using PRISMA 2020 guidelines, covering deterministic models such as AERMOD, CALINE4, WRF-Chem, CALPUFF, and HYSPLIT, as well as emerging machine-learning approaches. Results show that deterministic models remain dominant for urban and industrial assessments, yet their performance is limited by incomplete emission inventories, sparse monitoring networks, and complex tropical meteorology. Recent advances using machine learning, low-cost sensors, and satellite data have improved forecasting, though integration with policy and regulatory frameworks remains limited. Overall, Indonesia's modeling landscape is progressing but fragmented. Strengthening emission databases, enhancing model validation, and improving collaboration between research institutions and policymakers are essential, providing key scientific evidence to support the development of data-driven and policy-integrated air quality management frameworks in tropical archipelagic environments.</div></div>","PeriodicalId":37150,"journal":{"name":"Atmospheric Environment: X","volume":"30 ","pages":"Article 100457"},"PeriodicalIF":3.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147797495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wind-driven ash mobilization in post-wildfire Mediterranean forests: Wind tunnel insights","authors":"S. Rafael ,&nbsp;L.P. Correia ,&nbsp;M. Rebelo ,&nbsp;S. Sorte ,&nbsp;R. Martins ,&nbsp;V. Rodrigues ,&nbsp;O. González-Pelayo ,&nbsp;C. Borrego ,&nbsp;A.I. Miranda ,&nbsp;J.J. Keizer","doi":"10.1016/j.aeaoa.2026.100448","DOIUrl":"10.1016/j.aeaoa.2026.100448","url":null,"abstract":"<div><div>Wildfires alter multiple components of forest ecosystems, with post-fire ash forming surface layers that can be mobilised by wind. Although wind erosion is recognised as a relevant post-fire process, the mechanisms controlling ash detachment remain poorly understood. This study examines wind-driven ash detachment using a boundary layer wind tunnel and plate mass loss curves as a direct detachment indicator of ash layers from different forest types. Ash was collected from two sites in mainland Portugal dominated by young maritime pine (YP), mature maritime pine (MP), and eucalyptus (E3), and subjected to two levels of crown consumption (low, LCC; high, HCC). Five ash layer depths (1, 2, 5, 10, 20 mm) were tested for each sample. Results show that thicker layers (5-20 mm) were more easily mobilised at moderate wind speeds (4-6 m s⁻¹). Eucalyptus ash exhibited the highest resistance to detachment (5.4-7.2 m s⁻¹), compared to YP (4.4-5.5 m s⁻¹) and MP (4.0-5.6 m s⁻¹). These findings demonstrate clear interactions between ash properties, layer depth, and wind erosion peak-loss velocities, offering new insights into post-wildfire ash detachment and its potential for wind-driven redistribution.</div></div>","PeriodicalId":37150,"journal":{"name":"Atmospheric Environment: X","volume":"30 ","pages":"Article 100448"},"PeriodicalIF":3.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147797496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Daily outdoor PM2.5 exposure characterization and road edge effect during a 2022 - 2023 monitoring campaign in Gambia, Kenya and Mozambique","authors":"Terence Darlington Mushore ,&nbsp;Handsome Bongani Nyoni ,&nbsp;Laura Munthali ,&nbsp;Sibusisiwe Audrey Makhanya ,&nbsp;Laurine Chikoko ,&nbsp;Anotida Marrian Chapunza ,&nbsp;Stanley Luchters ,&nbsp;Matthew Chersich ,&nbsp;Fortunate Machingura ,&nbsp;Liberty Makacha ,&nbsp;Benjamin Barratt ,&nbsp;Hiten D. Mistry ,&nbsp;Marie Laure Volvert ,&nbsp;Cherlynn Dumbura ,&nbsp;Umberto D'Alessandro ,&nbsp;Anna Roca ,&nbsp;Esperana Sevene ,&nbsp;Herminio Cossa ,&nbsp;Marleen Temmerman ,&nbsp;Angela Koech ,&nbsp;Prestige Tatenda Makanga","doi":"10.1016/j.aeaoa.2026.100463","DOIUrl":"10.1016/j.aeaoa.2026.100463","url":null,"abstract":"<div><div>Air pollution is a major contributor to mortality and adverse health outcomes, particularly in pregnant women and children, with vehicular emissions as a key source. This study aimed to characterize long-term exposure to fine particulate matter (PM₂.₅), evaluate potential health risks, and quantify the contribution of road transport and proximity to roads in The Gambia, Kenya, and Mozambique. Multi-temporal personal exposure data were interpolated into continuous spatial surfaces and aggregated into daily averages, which were then compared with World Health Organization (WHO) guidelines to assess potential health impacts. Multi-distance buffers at 10 m intervals up to 1000m from major roads were created to examine pollutant variation with road proximity. Overlay analyses and linear regression models were applied to quantify the road-edge effect on pollution exposure. The Inverse Distance Weighting interpolation technique produced accurate PM₂.₅ field in all sites (R2&gt;0.55, MAE&lt;4 μg/m3 and RMSE&lt;10 μg/m3) based on leave-one-out cross-validation. PM₂.₅ concentrations were highest in The Gambia across all land use and land cover (LULC) types, reflecting localized industrial and vehicular emissions. Elevated pollutant levels were observed in herbaceous wetlands, bare land, and built-up areas. Most sites across all three countries exceeded WHO recommended thresholds, indicating significant health risks. PM₂.₅ decreased with distance from roads in Rabai (Kenya) and Mozambique, while in other sites it increased away from roads. These findings highlight the combined influence of multiple local sources, including traffic, fire smoke, wetlands, and industry, on pollutant exposure. The study demonstrates the utility of WHO thresholds for health risk assessment and shows how road proximity affects pollutant dispersal. The results provide critical insights for modeling air pollution exposure and informing mitigation strategies in sub-Saharan Africa.</div></div>","PeriodicalId":37150,"journal":{"name":"Atmospheric Environment: X","volume":"30 ","pages":"Article 100463"},"PeriodicalIF":3.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147991408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation of wake vortex transport of ultrafine particle emissions from the glide path to the ground","authors":"Frank Holzäpfel","doi":"10.1016/j.aeaoa.2026.100446","DOIUrl":"10.1016/j.aeaoa.2026.100446","url":null,"abstract":"<div><div>Ultrafine particle (UFP) emissions of aircraft may cause serious adverse health effects. The current study considers the transport of UFP emissions via the wake vortices generated by aircraft approaching Frankfurt Airport down to the ground. For this purpose, the fast-time Probabilistic Two-Phase wake vortex prediction model P2P has been enhanced for the prediction of the transport of a passive tracer with the descending wake vortex oval. The parameterisation of tracer transport considers the associated turbulent mixing processes of the vortex oval with its environment and the detrainment into a secondary wake, both causing the dilution of the tracer. The study considers the wind conditions prevailing in the year 2019 and the respective traffic mix of Frankfurt Airport. The presented results comprise the dwell times of the wake vortices reaching the ground, the corresponding passive tracer concentrations and the UFP numbers. The computed UFP numbers are set into perspective to UFP number concentrations measured at a distance of about 4 km to the airport using a mobile ground measuring station. It is found that the UFP emissions of approaching aircraft are small compared to other sources at the airport. Even UFP counts of direct wake vortex hits on the ground are on the order of the background concentrations. At a distance of 9 km from the runway ends the UFP numbers drop to less than 1% of the maximum ground immissions occurring near the runway thresholds.</div></div>","PeriodicalId":37150,"journal":{"name":"Atmospheric Environment: X","volume":"30 ","pages":"Article 100446"},"PeriodicalIF":3.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147650575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of urban carbon flux patterns: A case study of Hefei station","authors":"Zhongwei Lu ,&nbsp;Renmin Yuan ,&nbsp;Jiajia Hua ,&nbsp;Jiaoxu Mei ,&nbsp;Xiaoming Gao ,&nbsp;Xueyong Shen","doi":"10.1016/j.aeaoa.2026.100451","DOIUrl":"10.1016/j.aeaoa.2026.100451","url":null,"abstract":"<div><div>Cities are now central to global efforts to reduce CO₂ emissions, as they represent the major anthropogenic sources of carbon. Consequently, compiling urban carbon inventories, refining monitoring techniques, and investigating the distribution of sources and sinks in complex urban environments have become increasingly urgent. This study is based on data from an Eddy Covariance (EC) tower operated by the University of Science and Technology of China in downtown Hefei. The site represents a campus-influenced urban environment, with campus lawns and low-rise buildings in the near field and major roads in the broader footprint. By integrating high-resolution spatial data with flux-footprint modeling, we analyze the spatiotemporal patterns of urban CO₂ fluxes and their key drivers. Results show that CO₂ fluxes on weekdays exhibit a distinct bimodal diurnal cycle, while weekend emissions are 31.93% lower. Seasonal variability is governed by human activity and vegetation photosynthesis; winter emissions are 4.8-fold higher than those in summer. Spatial analysis attributes 4.36 kg CO₂·m⁻²·yr⁻¹ to urban traffic, the dominant source in the study area. After gap-filling missing observations with an artificial neural network (ANN) and an improved marginal-distribution-sampling (iMDS) method, the annual regional emission is estimated at 4.81 kg CO₂·m⁻²·yr⁻¹. The fact that urban traffic emissions account for roughly 91% of the total indicates that non-traffic sources largely offset one another, such that, once traffic is excluded, the study area is close to a carbon-neutral state.</div></div>","PeriodicalId":37150,"journal":{"name":"Atmospheric Environment: X","volume":"30 ","pages":"Article 100451"},"PeriodicalIF":3.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147740440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}