ACS ES&T Air最新文献

{"title":"Plume Detection and Emissions Quantification Potential Using a Dense Sensor Network","authors":"Milan Y. Patel,&nbsp;Yishu Zhu,&nbsp;Anna R. Winter,&nbsp;Naomi G. Asimow and Ronald C. Cohen*,&nbsp;","doi":"10.1021/acsestair.5c0006910.1021/acsestair.5c00069","DOIUrl":"https://doi.org/10.1021/acsestair.5c00069https://doi.org/10.1021/acsestair.5c00069","url":null,"abstract":"<p >Densely spaced sensor networks provide a unique opportunity for describing emissions from stationary and moving point sources and from intermittent events like fires or industrial flaring. As an example of what sensor networks can achieve, we describe quantification of emissions from a small urban fire in the Bay Area of California using the Berkeley Environmental Air-quality and CO₂ Network (BEACO₂N), a dense air quality and greenhouse gas monitoring network. Pollutant enhancements are measured at multiple sites, and the ensemble of observations are fit to a 2-D Gaussian model to characterize the extent of dilution prior to observation and derive emissions at the location of the fire. Distinct approaches are used for calibration of the CO₂, air quality gases, and PM_2.5 instruments. Consistency of the ratios at multiple locations downwind of the fire supports the precision of the network. We find that the fire emitted approximately 770 ± 30 kg of PM_2.5, 70,000 ± 20,000 kg of CO₂, 2500 ± 300 kg of CO, and 28 ± 9 kg of NO_<i>x</i>. The emission ratios are in the range of typical wildland fires. Using this example, we explore the minimum plume emissions that could be observed and quantified by the network.</p><p >This study demonstrates the potential of an air quality and greenhouse gas monitoring network to detect plumes and quantify emissions from point sources.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 6","pages":"1099–1106 1099–1106"},"PeriodicalIF":0.0,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsestair.5c00069","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144269849","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":"Machine-Learning-Based Estimation of Marine CHBr3 Emissions around Asia and the Implication on Bromine Radicals and Ozone Depletion","authors":"Jing Chen,&nbsp;Yuchen Liu,&nbsp;Jie Li,&nbsp;Chuang Qin,&nbsp;Xianyi Sun and Xiao Fu*,&nbsp;","doi":"10.1021/acsestair.4c0035710.1021/acsestair.4c00357","DOIUrl":"https://doi.org/10.1021/acsestair.4c00357https://doi.org/10.1021/acsestair.4c00357","url":null,"abstract":"<p >Ocean-produced, very short-lived bromine substances, such as bromoform (CHBr₃), can significantly affect the tropospheric and stratospheric bromine loading and ozone budget. However, large uncertainties exist for marine CHBr₃ emission estimations, especially around Asia. In this study, we establish a new marine emission inventory of CHBr₃, considering the physical and biogeochemical forces in the interaction of the ocean and atmosphere. The surface seawater concentrations are predicted based on expanded in situ CHBr₃ measurements and the machine-learning approach. The marine CHBr₃ emission is estimated to be 55.9 Gg Br yr^–1 around Asia, accounting for 20.4% of the global total. Our estimate is 18.7 Gg Br yr^–1 higher than the previously widely used bottom-up emission inventory, primarily due to discrepancies in the Western Pacific and the South China Sea. Higher estimated marine CHBr₃ emissions significantly affect the stratospheric bromine radicals and ozone over Asia, leading to a maximum increase of 13.6% in Br and 12.2% in BrO concentrations and thus up to a 2.5 ppbv reduction in stratospheric ozone. This study highlights the need for additional marine CHBr₃ observations in data-sparse regions to better quantify marine CHBr₃ emissions and assess their potential atmospheric impacts. This new approach also provides a valuable model framework to calculate sea–air fluxes for other compounds of interest.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 6","pages":"1069–1078 1069–1078"},"PeriodicalIF":0.0,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144269979","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":"Influence of Vehicle Design on Near-Road Concentrations of Traffic-Related Air Pollutants","authors":"Samuel Wilson,&nbsp;Naomi J. Farren,&nbsp;Yoann Bernard,&nbsp;Marvin D. Shaw,&nbsp;Kaylin Lee,&nbsp;Mallery Crowe,&nbsp;James D. Lee and David C. Carslaw*,&nbsp;","doi":"10.1021/acsestair.5c0005910.1021/acsestair.5c00059","DOIUrl":"https://doi.org/10.1021/acsestair.5c00059https://doi.org/10.1021/acsestair.5c00059","url":null,"abstract":"<p >Exposure to traffic-related air pollution (TRAP) is an ongoing health concern worldwide, particularly close to roads where concentrations are the highest. Near-road exposure is influenced by factors such as vehicle exhaust emission rates, pollutant composition, and dispersion behavior. In this work we apply a recently developed technique called <i>plume regression</i> based on fast-response roadside measurements, to better understand the variables affecting near-road TRAP concentrations. Of specific interest is determining the extent to which vehicle design and physical characteristics affect roadside exposure to important pollutants such as nitrogen oxides (NO_<i>x</i> = NO + NO₂). We find that the position of passenger car’s exhaust (tailpipe)─whether on the left or right side─results in a 40% difference in pollutant concentration contribution at the curbside. In the UK, only 20.1% of diesel passenger cars, the most significant vehicle class contributors to NO_<i>x</i> emissions, have their exhausts positioned on the right, the position associated with the lowest concentrations. If all diesel cars in the UK were equipped with right-positioned exhausts─the side farthest from the curb, curbside concentrations from these vehicles would be reduced by one-third. We also find evidence that electric vehicles (EVs) act to dilute the exhaust plumes of proximate fossil-fueled vehicles through vehicle-induced turbulence, reducing near-road TRAP exposure, a hitherto unrealized benefit of EVs.</p><p >Fast-response measurements of traffic-related pollutants show the physical attributes of a vehicle such as exhaust position influences near-road concentrations.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 6","pages":"1089–1098 1089–1098"},"PeriodicalIF":0.0,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsestair.5c00059","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144269831","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":"Anthropogenic Oxygenated Volatile Organic Compounds Dominate Atmospheric Oxidation Capacity and Ozone Production via Secondary Formation of Formaldehyde in the Urban Atmosphere","authors":"Hongtao Qian,&nbsp;Bingye Xu,&nbsp;Zhengning Xu*,&nbsp;Qiaoli Zou,&nbsp;Qianxin Zi,&nbsp;Hanfei Zuo,&nbsp;Fei Zhang,&nbsp;Jing Wei,&nbsp;Xiangyu Pei,&nbsp;WenXin Zhou,&nbsp;Lingling Jin,&nbsp;Xudong Tian,&nbsp;Wenlong Zhao* and Zhibin Wang,&nbsp;","doi":"10.1021/acsestair.4c0031710.1021/acsestair.4c00317","DOIUrl":"https://doi.org/10.1021/acsestair.4c00317https://doi.org/10.1021/acsestair.4c00317","url":null,"abstract":"<p >Oxygenated volatile organic compounds (OVOCs) play an important role in the photochemical formation of ozone (O₃). Comprehensive measurements and chemical box model analysis conducted in Hangzhou, China reveal that the formation of O₃ is strongly attributed to the increased atmospheric oxidation capacity (AOC). The observed OVOCs contribute 46.5 ± 8.3% to the AOC, especially during the pollution periods, with formaldehyde (HCHO) and acetaldehyde (CH₃CHO) accounting for 19 ± 3.8% and 13.8 ± 4.1%, respectively. Various OVOCs (especially CH₃CHO) act as key precursors for the initial production of the crucial radicals. These include the hydroperoxy radical (HO₂), methyl peroxy radical (CH₃O₂), and acetyl peroxy radical (CH₃CO₃), accounting for 53.7 ± 5.0%, 13.9 ± 2.5%, and 10.0 ± 2.4% of the daytime O₃ production (P(O₃)), respectively. HCHO acted as the key accelerator of HO₂ radical production and subsequently speeded up O₃ production. Model simulation and observational evidence reveal that the OVOC initiated secondary channel dominates the HCHO formation. The radical propagation chain of CH₃CO₃ → CH₃O₂→ CH₃O→ HO₂ accounts for 62.4 ± 6.9% of HCHO production. CH₃CHO chemistry can account for 14.0% of the production of O₃, and degradation of secondary HCHO derived from CH₃CHO accounts for 5.2% of total HO₂ production. These findings underscore the significant effect of OVOCs, particularly CH₃CHO, on AOC and O₃ production in the urban atmosphere in eastern China. Given the decreasing trend of NO_X concentration, model simulations under different NO_X levels further imply that reducing anthropogenic emission sources of OVOCs is a crucial strategy for current O₃ control, and excessive reduction of NO_X emissions (the daytime average concentration of NO_X decreases to below ∼ 2 ppb) may affect the effectiveness of reducing VOCs and promote a radical self-reaction.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 6","pages":"1033–1041 1033–1041"},"PeriodicalIF":0.0,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144269603","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":"Improving Temporal and Spatial Coverage of UK Black Carbon Measurements by Applying a Machine Learning Approach","authors":"I. S. Wong*,&nbsp;James D. Allan*,&nbsp;Gary W. Fuller and Anna Font,&nbsp;","doi":"10.1021/acsestair.4c0030610.1021/acsestair.4c00306","DOIUrl":"https://doi.org/10.1021/acsestair.4c00306https://doi.org/10.1021/acsestair.4c00306","url":null,"abstract":"<p >The WHO Global Air Quality Guidelines suggest that continuous and systematic monitoring of black carbon (BC) should be implemented due to BC from both transport and residential wood burning posing adverse health effects. Beyond PM₁₀ and PM_2.5, BC serves as a strong indicator for the study of health risks related to primary combustion sources. In the UK, only 14 monitoring stations report BC concentrations, contrasting with the extensive network measuring NO_<i>x</i>, SO₂, O₃, CO, PM₁₀ and PM_2.5 and meteorological parameters (more than 170 stations across the country). The sparse spatial and temporal coverage of BC data caused by this limitation constrains scientists’ research and policy makers’ decisions. This study applies machine learning algorithms to address this challenge: first, filling gaps in missing BC data at 9 urban and 4 rural background sites in the UK between 2009 and 2020, and then further estimating hourly concentrations of BC at 7 sites without observations (1 urban and 6 rural background sites). The result is a new data set with greater temporal and spatial coverage of BC data, providing a resource for further research on BC impacts such as epidemiological studies on health outcomes. Although the data are specific to the UK, the proposed methodology can potentially be applied to other countries.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 6","pages":"1020–1032 1020–1032"},"PeriodicalIF":0.0,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144269599","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":"Comprehensive Fuel and Emissions Measurements Highlight Uncertainties in Smoke Production Using Predictive Modeling Tools","authors":"Afsara Tasnia,&nbsp;Guadalupe Lara,&nbsp;Daniel Foster,&nbsp;Deep Sengupta,&nbsp;James D. A. Butler,&nbsp;Thomas W. Kirchstetter,&nbsp;Robert York,&nbsp;Nathan M. Kreisberg,&nbsp;Allen H. Goldstein,&nbsp;John J. Battles and Kelley C. Barsanti*,&nbsp;","doi":"10.1021/acsestair.4c0014210.1021/acsestair.4c00142","DOIUrl":"https://doi.org/10.1021/acsestair.4c00142https://doi.org/10.1021/acsestair.4c00142","url":null,"abstract":"<p >Predictive modeling tools, such as the First Order Fire Effects Model (FOFEM), are used to generate estimates of the effects from wildland fires, including fuel consumption and smoke emissions. Given the use of such models in planning and forecasting for wildland fires, coupled with the adverse health and climate impacts of smoke, there is a need to understand the sensitivity to model inputs and processes, evaluate smoke production, and identify critical uncertainties. In this work, FOFEM was applied to a series of prescribed burns at the Blodgett Forest Research Station (BFRS), a western mixed coniferous forest in northern California, adapted to a frequent low-severity fire regime. We evaluated the sensitivity of predicted smoke emissions to parametric uncertainty in model inputs, including fuel characteristics (composition, loading, and moisture) and emission factors (EFs), and structural uncertainty in the consumption model. The results of the modeling simulations and comparison with a unique and comprehensive suite of fuel and emissions measurements suggest that in this application of FOFEM, fuel loadings based on land cover maps had the highest uncertainty and resulted in the largest sensitivity in predicted smoke emissions. The use of land-cover-based fuel loading values significantly underpredicted gas and particle emissions from the prescribed burns by up to ∼80% for carbon monoxide (CO) and carbon dioxide (CO₂) and by up to ∼85% for fine particulate matter (PM_2.5). Improvement in the predicted smoke emissions could specifically be achieved by more accurate fuel loading data, particularly for duff and coarse wood, the consumption of which generated the majority of gas (∼50–70%) and particle (∼65%) emissions. For individual gaseous nonmethane organic compounds (NMOCs), predicted emissions were additionally sensitive to uncertainty in EFs, demonstrating that the accurate prediction of these NMOCs requires accurate representation of fuel consumption as well as representative EFs.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 6","pages":"982–997 982–997"},"PeriodicalIF":0.0,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144269959","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":"Investigating Aerial Data Preanalysis Schemes and Site-Level Methane Emission Aggregation Methods at Liquefied Natural Gas Facilities","authors":"Olga Khaliukova*,&nbsp;Yuanrui Zhu,&nbsp;William S. Daniels,&nbsp;Arvind P. Ravikumar,&nbsp;Gregory B. Ross,&nbsp;Selina A. Roman-White,&nbsp;Fiji C. George and Dorit M. Hammerling,&nbsp;","doi":"10.1021/acsestair.4c0030110.1021/acsestair.4c00301","DOIUrl":"https://doi.org/10.1021/acsestair.4c00301https://doi.org/10.1021/acsestair.4c00301","url":null,"abstract":"<p >Methane observations at liquefied natural gas (LNG) facilities play an important role in characterizing methane emissions from the natural gas supply chain. The large size and complexity of LNG facilities make quantifying emissions with ground-based monitoring systems challenging, making aerial platforms one of the preferred methods for detecting and estimating methane emissions at these sites. However, aerial measurements typically provide a snapshot of emissions at a given instance, necessitating further analytical steps to infer both annualized emissions and the range of possible emissions at different instances in time. This study uses aerial measurements at two U.S. LNG facilities from a Quantification, Monitoring, Reporting, and Verification project to characterize the distribution of temporally averaged emissions (i.e., annualized inventories) and possible site-level emissions at any given point in time (“instantaneous emissions”). The former provides uncertainty on the aerial measurement component of measurement-informed annual inventories, while the latter helps contextualize future snapshot measurements, such as those from aerial surveys or high-resolution satellite platforms, at LNG facilities. We find that instantaneous emissions may fall well outside of the distribution describing uncertainty in the annual inventory. We also compare different preanalysis schemes for aerial data, as existing literature does not provide a clear consensus on methods for doing so, especially at LNG facilities. We find the persistence assumption to be the most critical preanalysis factor.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 6","pages":"1009–1019 1009–1019"},"PeriodicalIF":0.0,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144269937","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":"Surface Uptake of Exogenous Volatile Organic Compounds Enhances the NO2-to-HONO Conversion on Soot","authors":"Xinyuan Zhao,&nbsp;Qiang Wang*,&nbsp;Peng Zhang*,&nbsp;Yonghong Wang*,&nbsp;Shuying Li,&nbsp;Zhanyu Su,&nbsp;Jun Liu,&nbsp;Biwu Chu,&nbsp;Qingxin Ma,&nbsp;Yujing Mu and Hong He,&nbsp;","doi":"10.1021/acsestair.5c0007210.1021/acsestair.5c00072","DOIUrl":"https://doi.org/10.1021/acsestair.5c00072https://doi.org/10.1021/acsestair.5c00072","url":null,"abstract":"<p >Heterogeneous reduction of nitrogen dioxides (NO₂) on soot has been suggested to be a source of nitrous oxide (HONO) in the atmosphere. However, conventional wisdom says that the contribution of NO₂ reduction on soot to HONO formation is limited due to the rapid deactivation of surface reductive sites in the atmosphere. On the contrary, we show that adsorbed anthropogenic and biogenic volatile organic compounds (VOCs), collectively called exogenous VOCs (EVOCs), can persistently promote the heterogeneous conversion of NO₂ to HONO on soot. The surface uptake of NO₂ driven by H₂O, coupled with the hydrogen reduction of NO₂ supported by EVOCs on elemental carbon (EC), is proposed to be the key pathway causing the persistent production of HONO. Furthermore, field observation conducted during biomass burning seasons in the North China Plain also showed that the presence of EVOCs promotes HONO production significantly. Our results imply that the continuous adsorption and conversion of EVOCs on soot surfaces may have a remarkable enhancing impact on the persistent conversion of NO₂ to HONO in the atmosphere.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 6","pages":"1107–1114 1107–1114"},"PeriodicalIF":0.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144269512","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":"Direct Observation of Liquid–Liquid Phase Separation and Core–Shell Morphology of PM2.5 Collected from Three Northeast Asian Cities and Implications for N2O5 Hydrolysis","authors":"Mijung Song*,&nbsp;Ying Li,&nbsp;Changjoon Seong,&nbsp;Hang Yang,&nbsp;Kyoung-Soon Jang,&nbsp;Zhijun Wu,&nbsp;Ji Yi Lee,&nbsp;Atsushi Matsuki and Joonyoung Ahn,&nbsp;","doi":"10.1021/acsestair.5c0004310.1021/acsestair.5c00043","DOIUrl":"https://doi.org/10.1021/acsestair.5c00043https://doi.org/10.1021/acsestair.5c00043","url":null,"abstract":"<p >The morphologies of aerosol particles significantly influence atmospheric processes, including heterogeneous chemistry. This study presents direct observations of liquid–liquid phase separation and the morphologies of PM_2.5 filter extracts collected from Seoul, Beijing, and Noto during autumn 2023. The PM_2.5 samples covered both polluted and clean environments and were predominantly organic-rich. Optical microscopy revealed that real-world samples from these cities underwent phase transitions with changing relative humidity and primarily existed in either two-liquid or three-phase states, while fully homogeneous or nonliquid states were rare. Moreover, a core–shell morphology, consisting of an organic shell and inorganic core, was frequently observed in the PM_2.5 samples. Calculations confirmed that the viscosity of the organic shell ranges from ∼10¹ Pa s in Seoul (liquid-like) to ∼10⁶ Pa s in Beijing (semisolid). As the shell becomes more viscous, the diffusivity of N₂O₅ decreases, thereby lowering the N₂O₅ uptake coefficient by 1–3 orders of magnitude and significantly restricting N₂O₅ uptake. These results highlight the crucial role of aerosol morphology in heterogeneous chemistry, as the organic-rich outer phase can significantly modify the reactive uptake coefficients and gas–particle interactions.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 6","pages":"1079–1088 1079–1088"},"PeriodicalIF":0.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144269590","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":"Potential Errors in CMAQ NO:NO2 Ratios and Upper Tropospheric NO2 Impacting the Interpretation of TROPOMI Retrievals","authors":"Abiola S. Lawal,&nbsp;T. Nash Skipper,&nbsp;Cesunica E. Ivey,&nbsp;Daniel L. Goldberg,&nbsp;Jennifer Kaiser and Armistead G. Russell*,&nbsp;","doi":"10.1021/acsestair.4c0019810.1021/acsestair.4c00198","DOIUrl":"https://doi.org/10.1021/acsestair.4c00198https://doi.org/10.1021/acsestair.4c00198","url":null,"abstract":"<p >Although Chemical Transport Models (CTMs) such as the Community Multiscale Air Quality Model (CMAQ) have been used in linking observations of trace gases to emissions and developing vertical column distributions, there remain consistent biases between CTM simulations and satellite retrievals. Simulated tropospheric NO₂ vertical column densities (VCDs) are generally higher over areas with large NO_<i>x</i> sources when compared with retrievals, while an opposite bias is found over low NO_<i>x</i> regions. Artificial (i.e., numerical) dilution in the model, where emissions are mathematically dispersed uniformly within the originating CTM grid, can impact modeled NO:NO₂ ratios, while lower CTM VCD levels often observed over rural areas can be attributed to missing emission sources of NO_<i>x</i> or flawed horizontal/vertical transport. Potential causes of both low and high biases are assessed in this study using CMAQ and Tropospheric Monitoring Instrument (TROPOMI) NO₂ retrievals. It was found that more detailed modeling of NO_<i>x</i> plumes to assess the NO:NO₂ ratio in two power plant plumes can mitigate the effect of artificial computational dilution, reducing the bias and overall differences in the observed vs modeled plumes (errors reduced by 30%). Adjustments of upper tropospheric NO₂ led to overall improvements, with a reduction in CMAQ bias (−43% to −29%) and improved spatial correlation (0.81 to 0.86). This study highlights the importance of having accurate modeled NO:NO₂ ratios when comparing models to retrievals and the impact of unintentional numerical dilution.</p><p >Underestimates of upper tropospheric NO₂ coupled with artificial mixing of NO_<i>x</i> emissions in chemical transport models can lead to low and high biases in simulated NO₂ vertical column densities when compared to satellite retrievals.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 6","pages":"998–1008 998–1008"},"PeriodicalIF":0.0,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsestair.4c00198","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144269549","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}