Atmospheric Chemistry and Physics最新文献

{"title":"The water-insoluble organic carbon in PM2.5 of typical Chinese urban areas: light-absorbing properties, potential sources, radiative forcing effects, and a possible light-absorbing continuum","authors":"Yangzhi Mo, Jun Li, Guangcai Zhong, Sanyuan Zhu, Shizhen Zhao, Jiao Tang, Hongxing Jiang, Zhineng Cheng, Chongguo Tian, Yingjun Chen, Gan Zhang","doi":"10.5194/acp-24-7755-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7755-2024","url":null,"abstract":"Abstract. Water-insoluble organic carbon (WIOC) constitutes a substantial portion of organic carbon (OC) and contributes significantly to light absorption by brown carbon (BrC), playing pivotal roles in climate forcing. China is a hotspot region with high levels of OC and BrC, but information regarding the sources and light-absorbing properties of WIOC on a national scale remains scarce. Here, we investigated the light-absorbing properties and sources of WIOC in 10 representative urban cities in China. On average, WIOC made up 33.4 ± 7.66 % and 40.5 ± 9.73 % of concentrations and light absorption at 365 nm (Abs365) of extractable OC (EX-OC), which includes relatively hydrophobic OC (WIOC and humic-like substances, HULIS-C) and hydrophilic OC (non-humic-like substances, non-HULIS-C). The mass absorption efficiency of WIOC at 365 nm (MAE365) was (1.59 ± 0.55 m2 (g C)−1) comparable to that of HULIS (1.54 ± 0.57 m2 (g C)−1) but significantly higher than non-HULIS (0.71 ± 0.28 m2 (g C)−1), indicating that hydrophobic OC possesses a stronger light-absorbing capacity than hydrophilic OC. Biomass burning (31.0 %) and coal combustion (31.1 %) were the dominant sources of WIOC, with coal combustion sources exhibiting the strongest light-absorbing capacity. Moreover, employing the simple forcing efficiency (SFE300–700 nm) method, we observed that WIOC exhibited the highest SFE300–700 nm (6.57 ± 5.37 W g−1) among the EX-OC fractions. The radiative forcing of EX-OC was predominantly contributed by hydrophobic OC (WIOC – 39.4 ± 15.5 % and HULIS – 39.5 ± 12.1 %). Considering the aromaticity, sources, and atmospheric processes of different carbonaceous components, we propose a light-absorbing carbonaceous continuum, revealing that components enriched with fossil sources tend to possess stronger light-absorbing capacity, higher aromatic levels, increased molecular weights, and greater recalcitrance in the atmosphere. Reducing fossil fuel emissions emerges as an effective means of mitigating both gaseous (CO2) and particulate light-absorbing carbonaceous warming components.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"2015 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141561306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Momentum flux characteristics of vertical propagating Gravity Waves","authors":"Prosper K. Nyassor, Cristiano M. Wrasse, Igo Paulino, Cosme A. O. B. Figueiredo, Ricardo A. Buriti, Hisao Takahashi, Delano Gobbi, Gabriel A. Giongo","doi":"10.5194/egusphere-2024-1982","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1982","url":null,"abstract":"<strong>Abstract.</strong> Simultaneous observations of airglow intensity, rotational temperature, and wind data at São João do Cariri (36.31° W; 07.40° S) by Co-located photometer, all-sky imager, and meteor radar were used to study the characteristics of vertical propagating gravity waves (GWs). Using the photometer data, the phase progression of GWs with the same propagation period in the OI 557.7nm, O₂, NaD-line, and OH (6-2) emission layers were then used to determine the upward or downward vertical propagation of the waves. The vertical phase speed and wavelength are estimated using the wave period and phase difference at different altitude. From the O₂ and OH (6-2) rotational temperatures, the total energy and the momentum flux of the downward propagating GWs were determined. For the upward propagating GW only the momentum flux and potential energy were estimated due to lack of observed wind. Further analysis of the momentum flux for each of the two events revealed that the momentum flux and potential energy of the downward propagating GWs increases with decreasing altitude. On the contrary, the GW momentum and energy of the upward propagating waves increases with increasing altitude. Thus, clearly demonstrating the transfer of momentum flux and energy from the source to the sink. This characteristic difference can be used to careful analysis the changes in GWs energy propagation due to reflection of non-primary GWs.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"31 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141561310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diverse sources and aging change the mixing state and ice nucleation properties of aerosol particles over the western Pacific and Southern Ocean","authors":"Jiao Xue, Tian Zhang, Keyhong Park, Jinpei Yan, Young Jun Yoon, Jiyeon Park, Bingbing Wang","doi":"10.5194/acp-24-7731-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7731-2024","url":null,"abstract":"Abstract. Atmospheric particles can impact cloud formation and play a critical role in regulating cloud properties. However, particle characteristics at the single-particle level and their ability to act as ice-nucleating particles (INPs) over the marine atmosphere are poorly understood. In this study, we present micro-spectroscopic characterizations and ice nucleation properties of particles collected during a cruise from South Korea to Antarctica in 2019. Most of the samples were dominated by fresh sea salt, aged sea salt, and sea salt mixed with sulfate particles, with total number percentages ranging from 48 % to 99 % over the western Pacific and the Southern Ocean. The mixing-state index of the particle population ranged from 50 % to 95 % over the Northern Hemisphere and Southern Hemisphere. Multiphase processes on sea salt particles resulted in chlorine deficiency. This selective aging process made the marine particle population more externally mixed. Ice nucleation onset conditions primarily for the deposition mode were measured and the investigated particles showed diverse ice nucleation abilities. The fresh sea salt particles with organic coatings exhibited the highest ice nucleation ability at a relative humidity with respect to ice as low as 121 %. The sea salt mixed sulfate particle was enriched in INPs by a factor of 1.9. Aging processes affected both the mixing state of the particles and their ice nucleation abilities. Our analysis shows that assuming an internally mixed particle population in the marine atmosphere can lead to errors of several orders of magnitude in predicting ice nucleation rates.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"15 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141561304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Australian Bushfire Emissions Result in Enhanced Polar Stratospheric Ice Clouds","authors":"Srinivasan Prasanth, Narayana Sarma Anand, Kudilil Sunilkumar, Subin Jose, Kenath Arun, Sreedharan K. Satheesh, Krishnaswamy K. Moorthy","doi":"10.5194/egusphere-2024-1849","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1849","url":null,"abstract":"<strong>Abstract.</strong> Extreme bushfire events amplify climate change by emitting greenhouse gases and destroying carbon sinks while causing economic damage through property destruction and even fatalities. One such bushfire occurred in Australia during 2019/2020, injecting large amounts of aerosols and gases into the stratosphere and depleting the ozone layer. While previous studies focused on the drivers behind ozone depletion, the bushfire impact on the polar stratospheric clouds (PSC), a paramount factor in ozone depletion, has not been extensively investigated so far. This study focuses on the effects of bushfire aerosols on the dynamics and stratospheric chemistry related to PSC formation and its pathways. An analysis from Aura's microwave limb sounder revealed enhanced hydrolysis of dinitrogen pentoxide significantly increased nitric acid (HNO₃) in the high-latitude lower stratosphere in early 2020. Using a novel methodology which retrieves formation pathways of PSCs from spaceborne lidar observations, we found that the enhanced HNO₃ condensed on bushfire aerosols, forming 82 % of Liquid Nitric Acid Trihydrate (LNAT), which rapidly converted to 77 % of ice, resulting in an anomalous high areal coverage of ice PSCs. This highlights the primary formation pathways of ice and LNAT and possibly helps us to simulate the PSC formation and denitrification process better in climate models. As tropospheric warming is anticipated to increase the frequency of extreme wildfire events and stratospheric cooling is expected to expand the PSC areal coverage, these findings will contribute significantly to a deeper understanding of the impacts of extreme wildfire events on stratospheric chemistry and PSC dynamics.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"140 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141557204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ozone trends in homogenized Umkehr, Ozonesonde, and COH overpass records","authors":"Irina Petropavlovskikh, Jeannette D. Wild, Kari Abromitis, Peter Effertz, Koji Miyagawa, Lawrence E. Flynn, Eliane Maillard-Barra, Robert Damadeo, Glen McConville, Bryan Johnson, Patrick Cullis, Sophie Godin-Beekmann, Gerald Ancellet, Richard Querel, Roeland Van Malderen, Daniel Zawada","doi":"10.5194/egusphere-2024-1821","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1821","url":null,"abstract":"<strong>Abstract.</strong> This study presents an updated evaluation of stratospheric ozone profile trends at Arosa/Davos/Hohenpeißenberg, Switzerland/Germany, Observatory de Haute Provence (OHP), France, Boulder, Colorado, Mauna Loa Observatory (MLO) and Hilo, Hawaii, and Lauder, New Zealand with focus on the ozone recovery period post 2000. Trends are derived using vertical ozone profiles from NOAA’s Dobson Network via the Umkehr method (with a recent new homogenization), ozonesondes, and the NOAA COHesive SBUV/OMPS satellite-based record (COH) sampled to match geographical coordinates of the ground-based stations used in this study. Analyses of long-term changes in stratospheric ozone time series were performed using the updated version (0.8.0) of the Long-term Ozone Trends and Uncertainties in the Stratosphere (LOTUS) Independent Linear Trend (ILT) regression model. This study finds a consistency of the trends derived from the different observational records, which is a key factor to the understanding of the recovery of the ozone layer after the implementation of the Montreal Protocol and its amendments that control ozone-depleting substances production and release into the atmosphere. The Northern Hemispheric Umkehr records of Aros/Davos, OHP, and MLO all show positive trends in the mid to upper stratosphere with trends peaking at ~+2 %/decade. Although the upper stratospheric ozone trends derived from COH satellite records are more positive than those detected by the Umkehr system, the agreement is within the two sigma uncertainty. Umkehr trends in the upper stratosphere at Boulder and Lauder are positive but not statistically significant, while COH trends are larger and statistically significant (within 2 sigma). In the lower stratosphere, trends derived from Umkehr and ozonesonde records are mostly negative (except for positive ozonesonde trends at OHP), however the uncertainties are quite large. Additional dynamical proxies were investigated in the LOTUS model at five ground-based sites. The use of additional proxies did not significantly change trends, but equivalent latitude reduced the uncertainty of the Umkehr and COH trends in the upper stratosphere and at higher latitudes. In lower layers, additional predictors (tropopause pressure for all stations, two extra components of Quasi-Biennial Oscillation at MLO, Arctic Oscillation at Arosa/Davos, OHP and MLO) improve the model fit and reduce trend uncertainties as seen by Umkehr and sonde.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"365 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141557203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atmospheric oxidation of 1,3-butadiene: influence of acidity and relative humidity on SOA composition and air toxic compounds","authors":"Mohammed Jaoui, Klara Nestorowicz, Krzysztof Rudzinski, Michael Lewandowski, Tadeusz Kleindienst, Julio Torres, Ewa Bulska, Witold Danikiewicz, Rafal Szmigielski","doi":"10.5194/egusphere-2024-2032","DOIUrl":"https://doi.org/10.5194/egusphere-2024-2032","url":null,"abstract":"<strong>Abstract.</strong> This study investigated the effect of relative humidity (RH) on the chemical composition of gas and particle phases formed from the photooxidation of 1,3-butadiene (13BD) in the presence of NOx under acidic and non-acidic conditions. The experiments were conducted in a 14.5 m³ smog chamber operated in a steady-state mode. Products were identified by high performance liquid chromatography, gas chromatography mass spectrometry and ultrahigh performance liquid chromatography coupled with high resolution mass spectrometry. More than 48 oxygenated products were identified including 33 oxygenated organics, 10 organosulfates (OSs), PAN, APAN, glyoxal, formaldehyde, and acrolein. Secondary organic aerosol (SOA) mass and reaction products were found to be dependent on RH and acidity of the aerosol. SOA mass, and most SOA products (i) were higher under acidic than non-acidic conditions, and (ii) decreased with increasing RH. Glyceric acid, threitols, threonic acids, four dimers, three unknowns, and four organosulfates were among the main species measured either under acidic or non-acidic conditions across all RH levels. Total secondary organic carbon and carbon yield decreased with increasing RH under both acidic and non-acidic conditions. The photochemical reactivity of 13BD in our systems decreased with increasing RH and was faster under non-acidic than acidic conditions. To determine the contribution of 13BD products to ambient aerosol, we analyzed PM_2.5 samples collected at three European monitoring stations located in Poland. The occurrence of several 13BD SOA products (e.g., glyceric acid, tartronic acid, threonic acid, tartaric acid, and OSs) in the field samples suggests that 13BD could contribute to ambient aerosol formation.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"49 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141557207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The 2023 global warming spike was driven by El Niño/Southern Oscillation","authors":"Shiv Priyam Raghuraman, Brian Soden, Amy Clement, Gabriel Vecchi, Sofia Menemenlis, Wenchang Yang","doi":"10.5194/egusphere-2024-1937","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1937","url":null,"abstract":"<strong>Abstract.</strong> Global-mean surface temperature rapidly increased 0.27 ± 0.05 K from 2022 to 2023. Such an interannual global warming spike is not unprecedented in the observational record with previous instances occurring in 1956–57 and 1976–77. However, why global warming spikes occur is unknown and the rapid global warming of 2023 has led to concerns that it could have been externally driven. Here we show that climate models that are subject only to internal variability can generate such spikes, but they are an uncommon occurrence (<span>𝑝</span> = 2.6 ± 0.1 %). However, when a prolonged La Niña immediately precedes an El Niño in the simulations, as occurred in nature in 1956–57, 1976–77, 2022–23, such spikes become much more common (<span>𝑝</span> = 16.5 ± 0.6 %). Furthermore, we find that nearly all simulated spikes (94 %) are associated with El Niño occurring that year. Thus, our results underscore the importance of El Niño/Southern Oscillation in driving the occurrence of global warming spikes such as the one in 2023, without needing to invoke anthropogenic forcing, such as changes in atmospheric concentrations of greenhouse gases or aerosols, as an explanation.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"25 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141557205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamical imprints on precipitation cluster statistics across a hierarchy of high-resolution simulations","authors":"Claudia Christine Stephan, Bjorn Stevens","doi":"10.5194/egusphere-2024-2020","DOIUrl":"https://doi.org/10.5194/egusphere-2024-2020","url":null,"abstract":"<strong>Abstract.</strong> Tropical precipitation cluster area and intensity distributions follow power laws, but the physical processes responsible for this macroscopic behavior remain unknown.We analyze global simulations at ten-kilometer horizontal resolution that are configured to have drastically varying degrees of realism, ranging from global radiative-convective equilibrium to fully realistic atmospheric simulations, to investigate how dynamics influence precipitation statistics. We find the presence of stirring and large-scale vertical overturning, as associated with substantial planetary and synoptic-scale variability, to be key for having cluster statistics approach power laws. The presence of such large-scale dynamics is reflected in steep vertical velocity spectra. Large-scale rising and sinking modulate the column water vapor and temperature field, leading to a heterogeneous distribution of moist and dry patches and regions of strong mass flux, in which large precipitation clusters form. Our findings suggest that power laws in Earth’s precipitation cluster statistics stem from the robust power laws of atmospheric motions.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"55 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141557206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A lightweight NO2-to-NOx conversion model for quantifying NOx emissions of point sources from NO2 satellite observations","authors":"Sandro Meier, Erik F. M. Koene, Maarten Krol, Dominik Brunner, Alexander Damm, Gerrit Kuhlmann","doi":"10.5194/acp-24-7667-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7667-2024","url":null,"abstract":"Abstract. Nitrogen oxides (NOx = NO + NO2) are air pollutants which are co-emitted with CO2 during high-temperature combustion processes. Monitoring NOx emissions is crucial for assessing air quality and for providing proxy estimates of CO2 emissions. Satellite observations, such as those from the TROPOspheric Monitoring Instrument (TROPOMI) on board the Sentinel-5P satellite, provide global coverage at high temporal resolution. However, satellites measure only NO2, necessitating a conversion to NOx. Previous studies have applied a constant NO2-to-NOx conversion factor. In this paper, we develop a more realistic model for NO2-to-NOx conversion and apply it to TROPOMI data of 2020 and 2021. To achieve this, we analysed plume-resolving simulations from the MicroHH large-eddy simulation model with chemistry for the Bełchatów (PL), Jänschwalde (DE), Matimba (ZA) and Medupi (ZA) power plants, as well as a metallurgical plant in Lipetsk (RU). We used the cross-sectional flux method to calculate NO, NO2 and NOx line densities from simulated NO and NO2 columns and derived NO2-to-NOx conversion factors as a function of the time since emission. Since the method of converting NO2 to NOx presented in this paper assumes steady-state conditions and that the conversion factors can be modelled by a negative exponential function, we validated the conversion factors using the same MicroHH data. Finally, we applied the derived conversion factors to TROPOMI NO2 observations of the same sources. The validation of the NO2-to-NOx conversion factors shows that they can account for the NOx chemistry in plumes, in particular for the conversion between NO and NO2 near the source and for the chemical loss of NOx further downstream. When applying these time-since-emission-dependent conversion factors, biases in NOx emissions estimated from TROPOMI NO2 images are greatly reduced from between −50 % and −42 % to between only −9.5 % and −0.5 % in comparison with reported emissions. Single-overpass estimates can be quantified with an uncertainty of 20 %–27 %, while annual NOx emission estimates have uncertainties in the range of 4 %–21 % but are highly dependent on the number of successful retrievals. Although more simulations covering a wider range of meteorological and trace gas background conditions will be needed to generalise the approach, this study marks an important step towards a consistent, uniform, high-resolution and near-real-time estimation of NOx emissions – especially with regard to upcoming NO2-monitoring satellites such as Sentinel-4, Sentinel-5 and CO2M.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"49 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The role of interfacial tension in the size-dependent phase separation of atmospheric aerosol particles","authors":"Ryan Schmedding, Andreas Zuend","doi":"10.5194/egusphere-2024-1690","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1690","url":null,"abstract":"<strong>Abstract.</strong> Atmospheric aerosol particles span orders of magnitude in size. In ultrafine particles, the energetic contributions of surfaces and interfaces to the Gibbs energy become significant and increase in importance as particle diameter decreases. For these particles, the thermodynamic equilibrium state depends on size, composition, and temperature. Various aerosol systems have been observed to undergo liquid–liquid phase separation (LLPS), impacting equilibrium gas–particle partitioning, modifying physicochemical properties of the particle phases, and influencing cloud droplet activation. Numerous laboratory experiments have characterized the onset relative humidity of LLPS in larger aerosol particles and macroscopic bulk systems. However, in sufficiently small particles, the interfacial tension between two liquid phases constitutes an energetic barrier that may prevent the formation of an additional liquid phase. Determining said small-size limit is a key question. We introduce a predictive droplet model based on the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients model. This model enables size-dependent computations of surface and interfacial tension effects on bulk–surface partitioning within phase-separated and single-phase particles. We evaluate four approaches for computing interfacial tension in multicomponent droplets, including a new method introduced in this work. Of the approaches tested, Antonov's rule best matches observed liquid–liquid interfacial tensions in highly immiscible mixtures, while a modified Butler equation fits well in more miscible systems. We find that two approaches substantially lower the onset relative humidity of LLPS for the studied systems.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"9 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}