scholarly journals Secondary inorganic aerosol simulations for Europe with special attention to nitrate

2004 ◽  
Vol 4 (3) ◽  
pp. 857-874 ◽  
Author(s):  
M. Schaap ◽  
M. van Loon ◽  
H. M. ten Brink ◽  
F. J. Dentener ◽  
P. J. H. Builtjes
Keyword(s):  
Seasonal Variation ◽  
Nitric Acid ◽  
Ammonium Nitrate ◽  
Model Simulation ◽  
Volatile Component ◽  
Sea Salt ◽  
Heterogeneous Reactions ◽  
Aerosol Formation ◽  
High Ammonia ◽  
Nitrate Concentrations

Abstract. Nitrate is an important component of (secondary inorganic) fine aerosols in Europe. We present a model simulation for the year 1995 in which we account for the formation of secondary inorganic aerosols including ammonium sulphate and ammonium nitrate, a semi volatile component. For this purpose, the chemistry-transport model LOTOS was extended with a thermodynamic equilibrium module and additional relevant processes to account for secondary aerosol formation and deposition. During winter, fall and especially spring high nitrate levels are projected over north western, central and eastern Europe. During winter nitrate concentrations are highest in Italy, in accordance with observed data. In winter nitric acid, the precursor for aerosol nitrate is formed through heterogeneous reactions on the surface of aerosols. Modelled and observed sulphate concentrations show little seasonal variation. Compared to sulphate levels, appreciable ammonium nitrate concentrations in summer are limited to those areas with high ammonia emissions, e.g. the Netherlands, since high ammonia concentrations are necessary to stabilise this aerosol component at high temperatures. As a consequence of the strong seasonal variation in nitrate levels the AOD depth of nitrate over Europe is especially significant compared to that of sulphate in winter and spring when equal AOD values are calculated over large parts of Europe. Averaged over all stations the model reproduces the measured concentrations for NO3, SO4, NH4, TNO3 (HNO3+NO3), TNH4 (NH3+NH4) and SO2 within 20%. The daily variation is captured well, albeit that the model does not always represent the amplitude of single events. The model underestimates wet deposition which was attributed to the crude representation of cloud processes. Comparison of retrieved and computed aerosol optical depth (AOD) showed that the model underestimates AOD significantly, which was expected due to the lack of carbonaceous aerosols, sea salt and dust in the model. The treatment of ammonia was found to be a major source for uncertainties in the model representation of secondary aerosols. Also, inclusion of sea salt is necessary to properly assess the nitrate and nitric acid levels in marine areas.

scholarly journals The nitrate aerosol field over Europe: simulations with an atmospheric chemistry-transport model of intermediate complexity

2003 ◽  
Vol 3 (6) ◽  
pp. 5919-5976 ◽  
Author(s):  
M. Schaap ◽  
M. van Loon ◽  
H. M. ten Brink ◽  
F. J. Dentener ◽  
P. J. H. Builtjes
Keyword(s):  
Nitric Acid ◽  
The Netherlands ◽  
Ammonium Nitrate ◽  
Transport Model ◽  
Chemistry Transport Model ◽  
Intermediate Complexity ◽  
High Ammonia ◽  
Nitrate Concentrations ◽  
The Impact ◽  
North Western

Abstract. Nitrate is an important component of fine aerosols in Europe. We present a model simulation for the year 1995 in which we account for the formation of the ammonium nitrate, a semi volatile component. For this purpose, LOTOS, a chemistry-transport model of intermediate complexity, was extended with a thermodynamic equilibrium module and additional relevant processes to account for aerosol formation and deposition. Our earlier analysis of data on (ammonium) nitrate in Europe was used for model evaluation. During winter, fall and especially spring high nitrate levels are projected over north western, central and eastern Europe. During winter nitrate concentrations are highest in the Po valley, Italy. This is in accordance with the field that was constructed from the data. In winter nitric acid, the precursor for aerosol nitrate, is formed through heterogeneous reactions on the surface of aerosols. Appreciable ammonium nitrate concentrations in summer are limited to those areas with high ammonia emissions, e.g. The Netherlands, since high ammonia concentrations are necessary to stabilise this aerosol component at high temperatures. Averaged over all stations the model reproduces the measured concentrations for NO3, SO4, NH4, TNO3, TNH4 and SO2 within 20%. The daily variation is captured well, albeit that the model does not always represents the amplitude of single events. The model underestimates wet deposition which was attributed to the crude representation of cloud processes. The treatment of ammonia was found to be the major source for uncertainties in the model representation of secondary aerosols. Also, inclusion of sea salt is necessary to properly assess the nitrate and nitric acid levels in marine areas. Over Europe the annual forcing by nitrate is calculated to be 25% of that by sulphate. In summer nitrate is found to be regionally important, e.g. in The Netherlands, where the forcing of nitrate and sulphate are calculated to be equal. In winter, spring and fall the nitrate forcing over Europe is about half that by sulphate. Over north western Europe and the alpine region the forcing by nitrate was calculated to be similar to that of sulphate. Overall, nitrate forcing is significant and should be taken into account to estimate the impact of regional climate change in Europe.

scholarly journals Evaporating brine from frost flowers with electron microscopy, and implications for atmospheric chemistry and sea-salt aerosol formation

2017 ◽  
Author(s):  
Xin Yang ◽  
Vilém Neděla ◽  
Jiří Runštuk ◽  
Gabriela Ondrušková ◽  
Ján Krausko ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Ambient Air ◽  
Sea Salt ◽  
Heterogeneous Reactions ◽  
Environmental Scanning ◽  
Aerosol Formation ◽  
Ice Surface ◽  
Spatial Dimensions ◽  
Frost Flowers ◽  
External Forces

Abstract. An environmental scanning electron microscope was used for the first time to obtain well-resolved images, in both temporal and spatial dimensions, of lab-prepared frost flowers (FFs) under evaporation within the chamber temperature range from −5 °C to −18 °C and pressures above 500 Pa. Our scanning shows temperature-dependent NaCl speciation: the brine covering the ice was observed at all conditions, whereas the NaCl crystals were formed at temperatures below −10 °C as the brine oversaturation was achieved. Finger-like ice structures covered by the brine, with a diameter of several micrometres and length of tens to one hundred micrometres, are exposed to the ambient air. The brine-covered fingers are highly flexible and cohesive. The exposure of the liquid brine on the micrometric fingers indicates a significant increase in the brine surface area compared to that of the flat ice surface at high temperatures, whereas the NaCl crystals can become sites of heterogeneous reactivity at lower temperatures. There is no evidence that, without external forces, salty FFs could automatically fall apart to create a number of sub-particles at the scale of micrometres as the exposed brine fingers seem cohesive and hard to break in the middle. The fingers tend to combine together to form large spheres and then join back to the mother body, eventually forming a large chunk of salt after complete dehydration. A present microscopic observation rationalizes several previously unexplained observations, namely, that FFs are not a direct source of sea salt aerosols and that saline ice crystals under evaporation could accelerate the heterogeneous reactions of bromine liberation.

scholarly journals Evaporating brine from frost flowers with electron microscopy and implications for atmospheric chemistry and sea-salt aerosol formation

2017 ◽  
Vol 17 (10) ◽  
pp. 6291-6303 ◽  
Author(s):  
Xin Yang ◽  
Vilém Neděla ◽  
Jiří Runštuk ◽  
Gabriela Ondrušková ◽  
Ján Krausko ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Ambient Air ◽  
Sea Salt ◽  
Heterogeneous Reactions ◽  
Environmental Scanning ◽  
Aerosol Formation ◽  
Ice Surface ◽  
Spatial Dimensions ◽  
Frost Flowers ◽  
External Forces

Abstract. An environmental scanning electron microscope (ESEM) was used for the first time to obtain well-resolved images, in both temporal and spatial dimensions, of lab-prepared frost flowers (FFs) under evaporation within the chamber temperature range from −5 to −18 °C and pressures above 500 Pa. Our scanning shows temperature-dependent NaCl speciation: the brine covering the ice was observed at all conditions, whereas the NaCl crystals were formed at temperatures below −10 °C as the brine oversaturation was achieved. Finger-like ice structures covered by the brine, with a diameter of several micrometres and length of tens to 100 µm, are exposed to the ambient air. The brine-covered fingers are highly flexible and cohesive. The exposure of the liquid brine on the micrometric fingers indicates a significant increase in the brine surface area compared to that of the flat ice surface at high temperatures; the NaCl crystals formed can become sites of heterogeneous reactivity at lower temperatures. There is no evidence that, without external forces, salty FFs could automatically fall apart to create a number of sub-particles at the scale of micrometres as the exposed brine fingers seem cohesive and hard to break in the middle. The fingers tend to combine together to form large spheres and then join back to the mother body, eventually forming a large chunk of salt after complete dehydration. The present microscopic observation rationalizes several previously unexplained observations, namely, that FFs are not a direct source of sea-salt aerosols and that saline ice crystals under evaporation could accelerate the heterogeneous reactions of bromine liberation.

scholarly journals Exploring the sensitivity of atmospheric nitrate concentrations to nitric acid uptake rate using the Met Office's Unified Model

2021 ◽  
Vol 21 (20) ◽  
pp. 15901-15927
Author(s):  
Anthony C. Jones ◽  
Adrian Hill ◽  
Samuel Remy ◽  
N. Luke Abraham ◽  
Mohit Dalvi ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Ammonium Nitrate ◽  
Thermodynamic Equilibrium ◽  
Unified Model ◽  
Limiting Factor ◽  
Acid Uptake ◽  
Fast Simulation ◽  
Near Surface ◽  
Uptake Rates ◽  
Nitrate Concentrations

Abstract. Ammonium nitrate is a major aerosol constituent over many land regions and contributes to air pollution episodes, ecosystem destruction, regional haze, and aerosol-induced climate forcing. Many climate models that represent ammonium nitrate assume that the ammonium–sulfate–nitrate chemistry reaches thermodynamic equilibrium instantaneously without considering kinetic limitations on condensation rates. The Met Office's Unified Model (UM) is employed to investigate the sensitivity of ammonium nitrate concentrations to the nitric acid uptake coefficient (γ) in a newly developed nitrate scheme in which first-order condensation theory is utilised to limit the rate at which thermodynamic equilibrium is attained. Two values of γ representing fast (γ=0.193) and slow (γ=0.001) uptake rates are tested in 20-year global UM integrations. The global burden of nitrate associated with ammonium in the “fast” simulation (0.11 Tg[N]) is twice as great as in the “slow” simulation (0.05 Tg[N]), while the top-of-the-atmosphere radiative impact of representing nitrate is −0.19 W m−2 in the fast simulation and −0.07 W m−2 in the slow simulation. In general, the fast simulation exhibits better spatial correlation with observed nitrate concentrations, while the slow simulation better resolves the magnitude of concentrations. Local near-surface nitrate concentrations are found to be highly correlated with seasonal ammonia emissions, suggesting that ammonia is the predominant limiting factor controlling nitrate prevalence. This study highlights the high sensitivity of ammonium nitrate concentrations to nitric acid uptake rates and provides a novel mechanism for reducing nitrate concentration biases in climate model simulations. The new UM nitrate scheme represents a step change in aerosol modelling capability in the UK across weather and climate timescales.

scholarly journals Fine particle pH and gas-particle phase partitioning of inorganic species in Pasadena, California, during the 2010 CalNex campaign

2017 ◽  
Author(s):  
Hongyu Guo ◽  
Jiumeng Liu ◽  
Karl Froyd ◽  
James M. Robert ◽  
Patrick R. Veres ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Fine Particle ◽  
Eastern Mediterranean ◽  
Sea Salt ◽  
Phase Partitioning ◽  
Complex Interactions ◽  
Southeastern Us ◽  
Internal Mixing ◽  
Inorganic Species ◽  
Nitrate Concentrations

Abstract. pH is a fundamental aerosol property that affects ambient particle concentration and composition, linking pH to all aerosol environmental impacts. Here, PM1 and PM2.5 pH are calculated based on data from measurements during the California Research at the Nexus of Air Quality and Climate Change (CalNex) study from 15 May to 15 June 2010 in Pasadena CA. Particle pH and water were predicted with the ISORROPIA-II thermodynamic model and validated by comparing predicted to measured gas-particle partitioning of inorganic nitrate, ammonium and chloride. The study mean ± standard deviation PM1 pH was 1.9 ± 0.5 for the SO42−-NO3−-NH4+-HNO3-NH3 system. For PM2.5, internal mixing of sea salt components (SO42−-NO3−-NH4+-Na+-Cl−-K+-HNO3-NH3-HCl system) raised the bulk pH to 2.7 ± 0.3 and improved predicted nitric acid partitioning with PM2.5 components. The results show little effect of sea salt on PM1 pH, but significant effects on PM2.5 pH. A mean PM1 pH of 1.9 at Pasadena was approximately one unit higher than what we have reported in the southeastern US, despite similar temperature, relative humidity and sulfate ranges and is due to higher total nitrate concentrations (nitric acid plus nitrate) relative to sulfate, a situation where particle water is affected by semi-volatile nitrate concentrations. Under these conditions nitric acid partitioning can further promote nitrate formation by increasing aerosol water, which raises pH by dilution, further increasing nitric acid partitioning and resulting in a significant increase in fine particle nitrate and pH. This study provides insights on the complex interactions between particle pH and nitrate in a summertime coastal environment and a contrast to recently reported pH in the eastern US in summer and winter and the eastern Mediterranean. All studies have consistently found highly acidic PM1 with pH generally below 3.

scholarly journals Exploring the sensitivity of atmospheric nitrate concentrations to nitric acid uptake rate using the Met Office's Unified Model

2021 ◽  
Author(s):  
Anthony C. Jones ◽  
Adrian Hill ◽  
Samuel Remy ◽  
N. Luke Abraham ◽  
Mohit Dalvi ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Ammonium Nitrate ◽  
Thermodynamic Equilibrium ◽  
Unified Model ◽  
Limiting Factor ◽  
Acid Uptake ◽  
Fast Simulation ◽  
Near Surface ◽  
Uptake Rates ◽  
Nitrate Concentrations

Abstract. Ammonium nitrate is a major aerosol constituent over many land regions and contributes to air pollution episodes, ecosystem destruction, regional haze, and aerosol-induced climate forcing. Many climate models that represent ammonium nitrate assume that the ammonium-sulphate-nitrate chemistry reaches thermodynamic equilibrium instantaneously without considering kinetic limitations on condensation rates. The Met Office's Unified Model (UM) is employed to investigate the sensitivity of ammonium nitrate concentrations to the nitric acid uptake coefficient (γ) in a newly-developed nitrate scheme in which first order condensation theory is utilised to limit the rate at which thermodynamic equilibrium is attained. Two values of γ representing fast (γ = 0.193) and slow (γ = 0.001) uptake rates are tested in 20-year global UM integrations. The global burden of nitrate associated with ammonium in the “fast” simulation (0.11 Tg[N]) is twice as great as in the “slow” simulation (0.05 Tg[N]), while the top-of-the-atmosphere radiative impact of representing nitrate is −0.19 Wm−2 in the “fast” simulation and −0.07 Wm−2 in the “slow” simulation. In general, the “fast” simulation exhibits better spatial correlation with observed nitrate concentrations while the “slow” simulation better resolves the magnitude of concentrations. Local near-surface nitrate concentrations are found to be highly correlated with seasonal ammonia emissions suggesting that ammonia is the predominant limiting factor controlling nitrate prevalence. This study highlights the high sensitivity of ammonium nitrate concentrations to nitric acid uptake rates and provides a mechanism for reducing nitrate concentration biases in climate model simulations. The new UM nitrate scheme represents a step-change in aerosol modelling capability in the UK across weather and climate timescales.

scholarly journals Environmentally dependent dust chemistry of a super Asian dust storm in March 2010: observation and simulation

2017 ◽  
Author(s):  
Qiongzhen Wang ◽  
Xinyi Dong ◽  
Joshua S. Fu ◽  
Jian Xu ◽  
Congrui Deng ◽  
...  
Keyword(s):  
Air Quality ◽  
Dust Storm ◽  
Model Simulation ◽  
Eastern China ◽  
Heterogeneous Reactions ◽  
Anthropogenic Emissions ◽  
Aerosol Formation ◽  
Air Quality Model ◽  
Near Surface ◽  
The Impact

Abstract. Near surface and vertical in situ measurements of atmospheric aerosols were conducted in Shanghai during March 19–27, 2010 to explore the transport and chemical evolution of dust aerosols in a super dust storm. An air quality model with optimized physical dust emission scheme and newly implemented dust chemistry was utilized to study the impact of dust chemistry on regional air quality. Two discontinuous dust periods were observed with one travelling over Northern China (DS1) and the other passing over the coastal regions of Eastern China (DS2). Stronger mixing extents between dust and anthropogenic emissions were found in DS2, reflecting by the higher SO2/PM10 and NO2/PM10 ratios as well as typical pollution elemental species such as As, Cd, Pb, and Zn. As a result, the concentrations of SO42− and NO3− and the ratio of Ca2+/Ca were more elevated in DS2 than in DS1 but opposite for the [NH4+]/[SO42−+NO3−] ratio, suggesting the heterogeneous reactions between calcites and acid gases were significantly promoted in DS2 due to the higher level of relative humidity and gaseous pollution precursors. Lidar observation showed a columnar effect on the vertical structure of aerosol optical properties in DS1 that dust dominantly accounted for ~80–90 % of the total aerosol extinction from near the ground to ~700 m. In contrast, the dust plumes in DS2 were refrained within lower altitudes while the extinction from spheric particles exhibited maximum at a high altitude of ~800 m. The model simulation reproduced relatively consistent results with observations that strong impacts of dust heterogeneous reactions on secondary aerosol formation occurred in areas where the anthropogenic emissions were intensive. Compared to the sulfate simulation, the nitrate formation on dust is suggested to be improved in the future modeling efforts.

scholarly journals Fine particle pH and gas–particle phase partitioning of inorganic species in Pasadena, California, during the 2010 CalNex campaign

2017 ◽  
Vol 17 (9) ◽  
pp. 5703-5719 ◽  
Author(s):  
Hongyu Guo ◽  
Jiumeng Liu ◽  
Karl D. Froyd ◽  
James M. Roberts ◽  
Patrick R. Veres ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Fine Particle ◽  
Eastern Mediterranean ◽  
Sea Salt ◽  
Phase Partitioning ◽  
Complex Interactions ◽  
Southeastern Us ◽  
Internal Mixing ◽  
Inorganic Species ◽  
Nitrate Concentrations

Abstract. pH is a fundamental aerosol property that affects ambient particle concentration and composition, linking pH to all aerosol environmental impacts. Here, PM1 and PM2. 5 pH are calculated based on data from measurements during the California Research at the Nexus of Air Quality and Climate Change (CalNex) study from 15 May to 15 June 2010 in Pasadena, CA. Particle pH and water were predicted with the ISORROPIA-II thermodynamic model and validated by comparing predicted to measured gas–particle partitioning of inorganic nitrate, ammonium, and chloride. The study mean ± standard deviation PM1 pH was 1.9 ± 0.5 for the SO42−–NO3−–NH4+–HNO3–NH3 system. For PM2. 5, internal mixing of sea salt components (SO42−–NO3−–NH4+–Na+–Cl−–K+–HNO3–NH3–HCl system) raised the bulk pH to 2.7 ± 0.3 and improved predicted nitric acid partitioning with PM2. 5 components. The results show little effect of sea salt on PM1 pH, but significant effects on PM2. 5 pH. A mean PM1 pH of 1.9 at Pasadena was approximately one unit higher than what we have reported in the southeastern US, despite similar temperature, relative humidity, and sulfate ranges, and is due to higher total nitrate concentrations (nitric acid plus nitrate) relative to sulfate, a situation where particle water is affected by semi-volatile nitrate concentrations. Under these conditions nitric acid partitioning can further promote nitrate formation by increasing aerosol water, which raises pH by dilution, further increasing nitric acid partitioning and resulting in a significant increase in fine particle nitrate and pH. This study provides insights into the complex interactions between particle pH and nitrate in a summertime coastal environment and a contrast to recently reported pH in the eastern US in summer and winter and the eastern Mediterranean. All studies have consistently found highly acidic PM1 with pH generally below 3.

scholarly journals Nitrate formation from heterogeneous uptake of dinitrogen pentoxide during a severe winter haze in southern China

2018 ◽  
Author(s):  
Hui Yun ◽  
Weihao Wang ◽  
Tao Wang ◽  
Men Xia ◽  
Chuan Yu ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Time Resolution ◽  
Southern China ◽  
Fine Particulate Matter ◽  
Measurement Data ◽  
Heterogeneous Reactions ◽  
Chemical Mechanism ◽  
Rural Site ◽  
Phase Reaction ◽  
Dinitrogen Pentoxide

Abstract. Nitrate (NO3−) has become a major component of fine particulate matter (PM2.5) during hazy days in China. However, the role of the heterogeneous reactions of dinitrogen pentoxide (N2O5) in nitrate formation is not well constrained. In January 2017, a severe haze event occurred in the Pearl River Delta (PRD) of southern China during which high levels of PM2.5 (~ 400 μg m−3) and O3 (~ 160 ppbv) were observed at a semi-rural site (Heshan) in the western PRD. Nitrate concentrations were up to 108 μg m−3 (1 h time resolution), and the contribution of nitrate to PM2.5 reached nearly 40 %. Concurrent increases in NO3− and ClNO2 (with a maximum value of 8.3 ppbv in 1 min time resolution) were observed in the first several hours after sunset, indicating an intense N2O5 heterogeneous uptake on aerosols. The formation potential of NO3− via N2O5 heterogeneous reactions was estimated to be 39.7 to 77.3 μg m−3 in the early hours (3 to 6 h) after sunset based on the measurement data, which could completely explain the measured increase in the NO3− concentration during the same time period. Daytime production of nitric acid from the gas-phase reaction of OH + NO2 was calculated with a chemical box model built using the Master Chemical Mechanism (MCM v3.3.1) and constrained by the measurement data. The integrated nocturnal nitrate formed via N2O5 chemistry was comparable to or even higher than the nitric acid formed during the daytime. This study confirms that N2O5 heterogeneous chemistry was a significant source of aerosol nitrate during hazy days in southern China.

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