Pub Date : 2024-07-08DOI: 10.5194/egusphere-2024-1937
Shiv Priyam Raghuraman, Brian Soden, Amy Clement, Gabriel Vecchi, Sofia Menemenlis, Wenchang Yang
Abstract. 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 (𝑝 = 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 (𝑝 = 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.
{"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":null,"pages":null},"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}
Pub Date : 2024-07-08DOI: 10.5194/egusphere-2024-2020
Claudia Christine Stephan, Bjorn Stevens
Abstract. 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.
{"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":null,"pages":null},"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}
Pub Date : 2024-07-05DOI: 10.5194/acp-24-7667-2024
Sandro Meier, Erik F. M. Koene, Maarten Krol, Dominik Brunner, Alexander Damm, Gerrit Kuhlmann
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.
{"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":null,"pages":null},"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}
Pub Date : 2024-07-05DOI: 10.5194/egusphere-2024-1690
Ryan Schmedding, Andreas Zuend
Abstract. 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.
{"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":null,"pages":null},"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}
Pub Date : 2024-07-05DOI: 10.5194/egusphere-2024-2009
Albert Ansmann, Cristofer Jimenez, Daniel A. Knopf, Johanna Roschke, Johannes Bühl, Kevin Ohneiser, Ronny Engelmann
Abstract. A simulation study on the impact of wildfire smoke (aged organic aerosol particles) on cirrus formation in the central Arctic is presented. The simulations in this part 2 of a series of two articles complement the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) field observations, presented and discussed in part 1. The measurements were performed with lidar and radar aboard the ice breaker Polarstern at latitudes > 85° N during the winter half year 2019–2020. Main goal of the MOSAiC data analysis in part 1 was to gather a consistent set of indications for an impact of the observed aged Siberian wildfire smoke on the formation of embedded ice clouds. The combination of (a) mostly low ice crystal number concentration (ICNC) of 0.1–10 L−1 in almost all of the observed cirrus cloud virga, pointing to heterogeneous ice nucleation, (b) typically high ice saturation ratios in the upper part of the analyzed cirrus systems of around 1.3–1.4, and (c) significantly enhanced levels of smoke pollution characterized by particle surface area concentrations of the order of 5–15 µm2 cm−3 corroborate our hypothesis that wildfire smoke particles served as ice nucleating particles (INPs) in Arctic cirrus with typical cloud top temperatures of −60 to −75 °C. The observed high ice saturation ratios suggest relatively inefficient ice-active aerosol particles, as expected in the case of wildfire smoke. Main goal of the simulations in part 2 is to gain a deeper insight into the potential smoke influence on cirrus formation as a function of aerosol and meteorological conditions (temperature, relative humidity) and by considering realistic gravity wave characteristics (updraft speed, wave amplitude). The modeling effort uses lidar-derived values of INP number concentration as input and ICNC values retrieved from combined lidar-radar observations for comparison with the simulation results. The model allows us to simulate adiabatic lofting of air parcels triggered by gravity waves, nucleation of ice crystals on smoke particles (deposition ice nucleation), homogeneous freezing of background aerosol particles, the growth of the nucleated ice particles by deposition of water vapor on the crystals, and sedimentation effects. Observations of meteorological state parameters (temperature, relative humidity) with four radiosondes per day and of the aerosol and cirrus properties from continuous lidar and radar profiling permitted a realistic model-based investigation of the smoke influence on Arctic cirrus evolution. The simulations confirm that the smoke INPs were able to suppress homogeneous freezing of background aerosol particles and to trigger ice nucleation at high ice saturation ratios of 1.3–1.5 over the North Pole region at cirrus top temperatures mostly < −60 °C. The simulations further reveal that shallow gravity waves with amplitudes of the order of < 100 m and the compara
{"title":"Impact of wildfire smoke on Arctic cirrus formation, part 2: simulation of MOSAiC 2019−2020 cases","authors":"Albert Ansmann, Cristofer Jimenez, Daniel A. Knopf, Johanna Roschke, Johannes Bühl, Kevin Ohneiser, Ronny Engelmann","doi":"10.5194/egusphere-2024-2009","DOIUrl":"https://doi.org/10.5194/egusphere-2024-2009","url":null,"abstract":"<strong>Abstract.</strong> A simulation study on the impact of wildfire smoke (aged organic aerosol particles) on cirrus formation in the central Arctic is presented. The simulations in this part 2 of a series of two articles complement the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) field observations, presented and discussed in part 1. The measurements were performed with lidar and radar aboard the ice breaker Polarstern at latitudes > 85° N during the winter half year 2019–2020. Main goal of the MOSAiC data analysis in part 1 was to gather a consistent set of indications for an impact of the observed aged Siberian wildfire smoke on the formation of embedded ice clouds. The combination of (a) mostly low ice crystal number concentration (ICNC) of 0.1–10 L<sup>−1</sup> in almost all of the observed cirrus cloud virga, pointing to heterogeneous ice nucleation, (b) typically high ice saturation ratios in the upper part of the analyzed cirrus systems of around 1.3–1.4, and (c) significantly enhanced levels of smoke pollution characterized by particle surface area concentrations of the order of 5–15 µm<sup>2 </sup>cm<sup>−3</sup> corroborate our hypothesis that wildfire smoke particles served as ice nucleating particles (INPs) in Arctic cirrus with typical cloud top temperatures of −60 to −75 °C. The observed high ice saturation ratios suggest relatively inefficient ice-active aerosol particles, as expected in the case of wildfire smoke. Main goal of the simulations in part 2 is to gain a deeper insight into the potential smoke influence on cirrus formation as a function of aerosol and meteorological conditions (temperature, relative humidity) and by considering realistic gravity wave characteristics (updraft speed, wave amplitude). The modeling effort uses lidar-derived values of INP number concentration as input and ICNC values retrieved from combined lidar-radar observations for comparison with the simulation results. The model allows us to simulate adiabatic lofting of air parcels triggered by gravity waves, nucleation of ice crystals on smoke particles (deposition ice nucleation), homogeneous freezing of background aerosol particles, the growth of the nucleated ice particles by deposition of water vapor on the crystals, and sedimentation effects. Observations of meteorological state parameters (temperature, relative humidity) with four radiosondes per day and of the aerosol and cirrus properties from continuous lidar and radar profiling permitted a realistic model-based investigation of the smoke influence on Arctic cirrus evolution. The simulations confirm that the smoke INPs were able to suppress homogeneous freezing of background aerosol particles and to trigger ice nucleation at high ice saturation ratios of 1.3–1.5 over the North Pole region at cirrus top temperatures mostly < −60 °C. The simulations further reveal that shallow gravity waves with amplitudes of the order of < 100 m and the compara","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553430","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}
Abstract. High contents of reactive nitrogen components aggravate air pollution and could also impact ecosystem structures and functioning across the terrestrial–aquatic–marine continuum. However, the long-term historical trends and future predictions of reactive nitrogen components at the global scale still remain highly uncertain. In our study, field observations, satellite products, model outputs, and many other covariates were integrated into the multi-stage machine-learning model to capture the global patterns of reactive nitrogen components during 2000–2019. In order to decrease the estimate uncertainties in the future scenarios, the constructed reactive nitrogen component dataset for the historical period was utilised as the constraint to calibrate the CMIP6 dataset in four scenarios. The results suggested that the cross-validation (CV) R2 values of four species showed satisfying performance (R2>0.55). The concentrations of estimated reactive nitrogen components in China experienced persistent increases during 2000–2013, while they suffered drastic decreases from 2013, except for NH3. This might be associated with the impact of clean-air policies. However, in Europe and the United States, these compounds have remained relatively stable since 2000. In the future scenarios, SSP3-7.0 (traditional-energy scenario) and SSP1-2.6 (carbon neutrality scenario) showed the highest and lowest reactive nitrogen component concentrations, respectively. Although the reactive nitrogen concentrations in some heavy-pollution scenarios (SSP3-7.0) also experienced decreases during 2020–2100, SSP1-2.6 and SSP2-4.5 (middle-emission scenario) still showed more rapidly decreasing trends. Our results emphasise the need for carbon neutrality pathways to reduce global atmospheric N pollution.
{"title":"Global estimates of ambient reactive nitrogen components during 2000–2100 based on the multi-stage model","authors":"Rui Li, Yining Gao, Lijia Zhang, Yubing Shen, Tianzhao Xu, Wenwen Sun, Gehui Wang","doi":"10.5194/acp-24-7623-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7623-2024","url":null,"abstract":"Abstract. High contents of reactive nitrogen components aggravate air pollution and could also impact ecosystem structures and functioning across the terrestrial–aquatic–marine continuum. However, the long-term historical trends and future predictions of reactive nitrogen components at the global scale still remain highly uncertain. In our study, field observations, satellite products, model outputs, and many other covariates were integrated into the multi-stage machine-learning model to capture the global patterns of reactive nitrogen components during 2000–2019. In order to decrease the estimate uncertainties in the future scenarios, the constructed reactive nitrogen component dataset for the historical period was utilised as the constraint to calibrate the CMIP6 dataset in four scenarios. The results suggested that the cross-validation (CV) R2 values of four species showed satisfying performance (R2>0.55). The concentrations of estimated reactive nitrogen components in China experienced persistent increases during 2000–2013, while they suffered drastic decreases from 2013, except for NH3. This might be associated with the impact of clean-air policies. However, in Europe and the United States, these compounds have remained relatively stable since 2000. In the future scenarios, SSP3-7.0 (traditional-energy scenario) and SSP1-2.6 (carbon neutrality scenario) showed the highest and lowest reactive nitrogen component concentrations, respectively. Although the reactive nitrogen concentrations in some heavy-pollution scenarios (SSP3-7.0) also experienced decreases during 2020–2100, SSP1-2.6 and SSP2-4.5 (middle-emission scenario) still showed more rapidly decreasing trends. Our results emphasise the need for carbon neutrality pathways to reduce global atmospheric N pollution.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553311","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}
Pub Date : 2024-07-05DOI: 10.5194/acp-24-7637-2024
Tanguy Lunel, Maria Antonia Jimenez, Joan Cuxart, Daniel Martinez-Villagrasa, Aaron Boone, Patrick Le Moigne
Abstract. During the warm months of the year in Catalonia, the marine air overcomes the coastal mountain range and reaches the eastern Ebro sub-basin. This phenomenon is called marinada and has recently been thoroughly characterized for the first time by Jiménez et al. (2023), based on surface climatological data. However, the main physical mechanisms involved in its arrival and propagation remain to be discovered. This study aims to understand how the marinada is formed and how it interacts with the already developed atmospheric boundary layer. Surface and atmospheric observations are used in combination with the coupled surface–atmosphere model Meso-NH to reveal the mechanisms at play. It is shown that the marinada is generated by the advection of a cool marine air mass over the Catalan Pre-coastal Range by the action of the sea breeze and the upslope wind. This marine air mass then flows into the Ebro basin, creating what is known as the marinada. The characteristics and dynamics of the marinada allow it to be classified as a fall wind. It is also shown that the arrival, propagation and decay of the marinada is strongly dependent on the larger-scale weather situation: westerlies or thermal low. The current study provides a consistent framework for understanding the marinada, paving the way for better modeling and prediction of the phenomenon.
{"title":"The marinada fall wind in the eastern Ebro sub-basin: physical mechanisms and role of the sea, orography and irrigation","authors":"Tanguy Lunel, Maria Antonia Jimenez, Joan Cuxart, Daniel Martinez-Villagrasa, Aaron Boone, Patrick Le Moigne","doi":"10.5194/acp-24-7637-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7637-2024","url":null,"abstract":"Abstract. During the warm months of the year in Catalonia, the marine air overcomes the coastal mountain range and reaches the eastern Ebro sub-basin. This phenomenon is called marinada and has recently been thoroughly characterized for the first time by Jiménez et al. (2023), based on surface climatological data. However, the main physical mechanisms involved in its arrival and propagation remain to be discovered. This study aims to understand how the marinada is formed and how it interacts with the already developed atmospheric boundary layer. Surface and atmospheric observations are used in combination with the coupled surface–atmosphere model Meso-NH to reveal the mechanisms at play. It is shown that the marinada is generated by the advection of a cool marine air mass over the Catalan Pre-coastal Range by the action of the sea breeze and the upslope wind. This marine air mass then flows into the Ebro basin, creating what is known as the marinada. The characteristics and dynamics of the marinada allow it to be classified as a fall wind. It is also shown that the arrival, propagation and decay of the marinada is strongly dependent on the larger-scale weather situation: westerlies or thermal low. The current study provides a consistent framework for understanding the marinada, paving the way for better modeling and prediction of the phenomenon.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553348","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}
Pub Date : 2024-07-05DOI: 10.5194/egusphere-2024-1382
Theertha Kariyathan, Ana Bastos, Markus Reichstein, Wouter Peters, Julia Marshall
Abstract. The carbon uptake period (CUP) refers to the time of each year during which the rate of photosynthetic uptake surpasses that of respiration in the terrestrial biosphere, resulting in a net absorption of CO2 from the atmosphere to the land. Since climate drivers influence both photosynthesis and respiration, the CUP offers valuable insights into how the terrestrial biosphere responds to climate variations and affects the carbon budget. Several studies have assessed large-scale changes in CUP based on seasonal metrics from CO2 mole fraction measurements. However, an in-depth understanding of the sensitivity of the CUP as derived from the CO2 mole fraction data (CUPMR) to actual changes in the CUP of the net ecosystem exchange (CUPNEE) is missing. In this study, we specifically assess the impact of (i) atmospheric transport (ii) inter-annual variability in CUPNEE (iii) regional contribution to the signals that integrate at different background sites where CO2 dry air mole fraction measurements are made. We conducted idealized simulations where we imposed known changes (∆) to the CUPNEE in the Northern Hemisphere to test the effect of the aforementioned factors in CUPMR metrics at ten Northern Hemisphere sites. Our analysis indicates a significant damping of changes in the simulated ∆CUPMR due to the integration of signals with varying CUPNEE timing across regions. CUPMR at well-studied sites such as Mauna Loa, Barrow, and Alert showed only 50 % of the applied ∆CUPNEE under non interannually-varying atmospheric transport conditions. Further, our synthetic analyses conclude that interannual variability (IAV) in atmospheric transport accounts for a significant part of the changes in the observed signals. However, even after separating the contribution of transport IAV, the estimates of surface changes in CUP by previous studies are not likely to provide an accurate magnitude of the actual changes occurring over the surface. The observed signal experiences significant damping as the atmosphere averages out non-synchronous signals from various regions.
{"title":"How atmospheric CO2 can inform us on annual and decadal shifts in the biospheric carbon uptake period","authors":"Theertha Kariyathan, Ana Bastos, Markus Reichstein, Wouter Peters, Julia Marshall","doi":"10.5194/egusphere-2024-1382","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1382","url":null,"abstract":"<strong>Abstract.</strong> The carbon uptake period (CUP) refers to the time of each year during which the rate of photosynthetic uptake surpasses that of respiration in the terrestrial biosphere, resulting in a net absorption of CO<sub>2</sub> from the atmosphere to the land. Since climate drivers influence both photosynthesis and respiration, the CUP offers valuable insights into how the terrestrial biosphere responds to climate variations and affects the carbon budget. Several studies have assessed large-scale changes in CUP based on seasonal metrics from CO<sub>2</sub> mole fraction measurements. However, an in-depth understanding of the sensitivity of the CUP as derived from the CO<sub>2</sub> mole fraction data (CUP<sub>MR</sub>) to actual changes in the CUP of the net ecosystem exchange (CUP<sub>NEE</sub>) is missing. In this study, we specifically assess the impact of (i) atmospheric transport (ii) inter-annual variability in CUP<sub>NEE</sub> (iii) regional contribution to the signals that integrate at different background sites where CO<sub>2</sub> dry air mole fraction measurements are made. We conducted idealized simulations where we imposed known changes (∆) to the CUP<sub>NEE</sub> in the Northern Hemisphere to test the effect of the aforementioned factors in CUP<sub>MR</sub> metrics at ten Northern Hemisphere sites. Our analysis indicates a significant damping of changes in the simulated ∆CUP<sub>MR</sub> due to the integration of signals with varying CUP<sub>NEE</sub> timing across regions. CUP<sub>MR</sub> at well-studied sites such as Mauna Loa, Barrow, and Alert showed only 50 % of the applied ∆CUP<sub>NEE</sub> under non interannually-varying atmospheric transport conditions. Further, our synthetic analyses conclude that interannual variability (IAV) in atmospheric transport accounts for a significant part of the changes in the observed signals. However, even after separating the contribution of transport IAV, the estimates of surface changes in CUP by previous studies are not likely to provide an accurate magnitude of the actual changes occurring over the surface. The observed signal experiences significant damping as the atmosphere averages out non-synchronous signals from various regions.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553349","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}
Pub Date : 2024-07-05DOI: 10.5194/egusphere-2024-1381
Michel Legrand, Mstislav Vorobyev, Daria Bokuchava, Stanislav Kutuzov, Andreas Plach, Andreas Stohl, Alexandra Khairedinova, Vladimir Mikhalenko, Maria Vinogradova, Sabine Eckhardt, Susanne Preunkert
Abstract. To investigate the historical levels of atmospheric ammonia (NH3) pollution in south-eastern Europe, a 182 m long ice core was extracted from Mount Elbrus in the Caucasus, Russia. This ice core contains a record of ammonium (NH4+) levels from ~1750 CE (Common Era) to 2009 CE. The NH4+ ice core record indicates a 3.5-fold increase of annual concentrations from 34 ± 7 ng g-1 (~1750–1830) to 117 ± 23 ng g-1 over the recent decades (1980–2009). The increase remained moderate until 1950 CE (mean concentration of 49 ± 14 ng g-1 over the 1830–1950 period), and then accelerated to reach a maximum close to 120 ng g-1 in 1989. This ice core trend is compared to estimated past anthropogenic NH3 emissions in Europe by using state-of-the-art atmospheric transport modeling of submicron aerosols (FLEXPART model driven with 0.5° x 0.5° ERA5 reanalysis data). It is shown that in summer, when both vertical atmospheric mixing and agricultural NH3 emissions are strengthened, the NH4+ ice core trend is in good agreement with the course of estimated NH3 emissions from south-eastern Europe since ~1750 with a main contribution from south European Russia, Turkey, Georgia, and Ukraine. Examination of Mount Elbrus ice deposited over the second half of the 18th century when agricultural activities were less than 10% of those during the 1990s, suggest a pre-1750 annual NH4+ ice concentration related to natural emissions of 25 ng g-1. This pre-1750 natural level mainly related to natural soil emissions represents ~20% of the 1980–2009 NH4+ level, a level mainly related to current agricultural emissions that almost completely outweigh biogenic emissions from natural soils.
{"title":"Measurement Report: Changes of ammonia emissions since the 18th century in south-eastern Europe inferred from an Elbrus (Caucasus, Russia) ice core record","authors":"Michel Legrand, Mstislav Vorobyev, Daria Bokuchava, Stanislav Kutuzov, Andreas Plach, Andreas Stohl, Alexandra Khairedinova, Vladimir Mikhalenko, Maria Vinogradova, Sabine Eckhardt, Susanne Preunkert","doi":"10.5194/egusphere-2024-1381","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1381","url":null,"abstract":"<strong>Abstract.</strong> To investigate the historical levels of atmospheric ammonia (NH<sub>3</sub>) pollution in south-eastern Europe, a 182 m long ice core was extracted from Mount Elbrus in the Caucasus, Russia. This ice core contains a record of ammonium (NH<sub>4</sub><sup>+</sup>) levels from ~1750 CE (Common Era) to 2009 CE. The NH<sub>4</sub><sup>+</sup> ice core record indicates a 3.5-fold increase of annual concentrations from 34 ± 7 ng g<sup>-1</sup> (~1750–1830) to 117 ± 23 ng g<sup>-1</sup> over the recent decades (1980–2009). The increase remained moderate until 1950 CE (mean concentration of 49 ± 14 ng g<sup>-1</sup> over the 1830–1950 period), and then accelerated to reach a maximum close to 120 ng g<sup>-1 </sup>in 1989. This ice core trend is compared to estimated past anthropogenic NH<sub>3</sub> emissions in Europe by using state-of-the-art atmospheric transport modeling of submicron aerosols (FLEXPART model driven with 0.5° x 0.5° ERA5 reanalysis data). It is shown that in summer, when both vertical atmospheric mixing and agricultural NH<sub>3</sub> emissions are strengthened, the NH<sub>4</sub><sup>+</sup> ice core trend is in good agreement with the course of estimated NH<sub>3</sub> emissions from south-eastern Europe since ~1750 with a main contribution from south European Russia, Turkey, Georgia, and Ukraine. Examination of Mount Elbrus ice deposited over the second half of the 18<sup>th</sup> century when agricultural activities were less than 10% of those during the 1990s, suggest a pre-1750 annual NH<sub>4</sub><sup>+ </sup>ice concentration related to natural emissions of 25 ng g<sup>-1</sup>. This pre-1750 natural level mainly related to natural soil emissions represents ~20% of the 1980–2009 NH<sub>4</sub><sup>+ </sup>level, a level mainly related to current agricultural emissions that almost completely outweigh biogenic emissions from natural soils.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553429","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}
Abstract. This study investigated the potential effects of changes in inorganics on aerosol water uptake and, thus, on secondary organic aerosol (SOA) formation in wintertime haze based on the size-resolved measurements of non-refractory fine particulate matter (NR-PM2.5) in Xi'an, northwestern China. The composition of inorganic aerosol showed significant changes in winter 2018–2019 compared to winter 2013–2014, shifting from a sulfate-rich profile to a nitrate-rich profile. In particular, the fraction of sulfate and chloride decreased, but that of nitrate increased in the entire size range, while ammonium mainly increased at larger particle sizes. These changes thus resulted in a size-dependent evolution in water uptake. Increased water uptake was observed in most cases, mainly associated with enhanced contributions of both nitrate and ammonium, with the highest increase ratio reaching 5 %–35 % at larger particle sizes and higher relative humidity (RH>70 %). The non-negligible influence of chloride on aerosol water uptake was also emphasized. The random forest analysis coupled with a Shapley additive explanation algorithm (SHAP) further showed an enhanced relative importance of aerosol water in impacting SOA formation. Aerosol water exhibited a significant contribution to SOA formation during winter 2018–2019, particularly at larger particle sizes. The SHAP value of aerosol water increased alongside higher levels of aerosol water, indicating an enhanced contribution of aerosol water to SOA formation. This implies that the majority of enhanced aerosol water uptake at larger particle sizes and high RH might facilitate the efficient aqueous-phase SOA formation. This study highlights the key role of aerosol water as a medium to link inorganics and organics in their multiphase processes. As challenges to further improve China's air quality remain and because SOA plays an increasing role in haze pollution, these results provide insight into the size-resolved evolution characteristics and offer guidance for future controls.
摘要本研究基于对中国西北部西安市非难降解细颗粒物（NR-PM2.5）的粒径分辨测量，研究了无机物变化对气溶胶吸水的潜在影响，进而研究了冬季灰霾天气中二次有机气溶胶（SOA）形成的潜在影响。与2013-2014年冬季相比，2018-2019年冬季无机气溶胶的组成发生了显著变化，从富含硫酸盐的剖面转变为富含硝酸盐的剖面。其中，硫酸盐和氯化物的比例有所下降，但硝酸盐的比例在整个粒径范围内均有所上升，而铵主要在粒径较大时有所增加。因此，这些变化导致了摄水量随粒径而变化。在大多数情况下都能观察到吸水量的增加，这主要与硝酸盐和铵的增加有关，在粒径较大和相对湿度较高（相对湿度>70%）的情况下，吸水量增加比率最高，达到 5%-35%。氯化物对气溶胶吸水的影响也不容忽视。随机森林分析与沙普利加法解释算法（SHAP）相结合，进一步显示了气溶胶水在影响 SOA 形成方面的相对重要性。在2018-2019年冬季，气溶胶水对SOA的形成有显著贡献，尤其是在粒径较大的情况下。气溶胶水的SHAP值随着气溶胶水含量的增加而增加，表明气溶胶水对SOA形成的贡献增强。这意味着在粒径较大和相对湿度较高的情况下，气溶胶吸水的大部分增强可能会促进水相 SOA 的有效形成。这项研究强调了气溶胶水作为介质在无机物和有机物的多相过程中的关键作用。由于进一步改善中国空气质量的挑战依然存在，而且SOA在灰霾污染中扮演着越来越重要的角色，这些结果提供了对粒径分辨演变特征的深入了解，并为未来的控制提供了指导。
{"title":"Measurement report: Size-resolved secondary organic aerosol formation modulated by aerosol water uptake in wintertime haze","authors":"Jing Duan, Ru-Jin Huang, Ying Wang, Wei Xu, Haobin Zhong, Chunshui Lin, Wei Huang, Yifang Gu, Jurgita Ovadnevaite, Darius Ceburnis, Colin O'Dowd","doi":"10.5194/acp-24-7687-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7687-2024","url":null,"abstract":"Abstract. This study investigated the potential effects of changes in inorganics on aerosol water uptake and, thus, on secondary organic aerosol (SOA) formation in wintertime haze based on the size-resolved measurements of non-refractory fine particulate matter (NR-PM2.5) in Xi'an, northwestern China. The composition of inorganic aerosol showed significant changes in winter 2018–2019 compared to winter 2013–2014, shifting from a sulfate-rich profile to a nitrate-rich profile. In particular, the fraction of sulfate and chloride decreased, but that of nitrate increased in the entire size range, while ammonium mainly increased at larger particle sizes. These changes thus resulted in a size-dependent evolution in water uptake. Increased water uptake was observed in most cases, mainly associated with enhanced contributions of both nitrate and ammonium, with the highest increase ratio reaching 5 %–35 % at larger particle sizes and higher relative humidity (RH>70 %). The non-negligible influence of chloride on aerosol water uptake was also emphasized. The random forest analysis coupled with a Shapley additive explanation algorithm (SHAP) further showed an enhanced relative importance of aerosol water in impacting SOA formation. Aerosol water exhibited a significant contribution to SOA formation during winter 2018–2019, particularly at larger particle sizes. The SHAP value of aerosol water increased alongside higher levels of aerosol water, indicating an enhanced contribution of aerosol water to SOA formation. This implies that the majority of enhanced aerosol water uptake at larger particle sizes and high RH might facilitate the efficient aqueous-phase SOA formation. This study highlights the key role of aerosol water as a medium to link inorganics and organics in their multiphase processes. As challenges to further improve China's air quality remain and because SOA plays an increasing role in haze pollution, these results provide insight into the size-resolved evolution characteristics and offer guidance for future controls.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553346","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}
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