scholarly journals Ammonium nitrate evaporation and nitric acid condensation in DMT CCN counters

2014 ◽  
Vol 7 (5) ◽  
pp. 1377-1384 ◽  
Author(s):  
S. Romakkaniemi ◽  
A. Jaatinen ◽  
A. Laaksonen ◽  
A. Nenes ◽  
T. Raatikainen
Keyword(s):  
Nitric Acid ◽  
Ammonium Nitrate ◽  
Gas Phase ◽  
Aerosol Particles ◽  
Condensation Nucleus ◽  
Cloud Condensation Nucleus ◽  
Ambient Conditions ◽  
Particle Activation ◽  
Maximum Water ◽  
Ccn Activity

Abstract. The effect of inorganic semivolatile aerosol compounds on the cloud condensation nucleus (CCN) activity of aerosol particles was studied by using a computational model for a DMT-CCN counter, a cloud parcel model for condensation kinetics and experiments to quantify the modelled results. Concentrations of water vapour and semivolatiles as well as aerosol trajectories in the CCN column were calculated by a computational fluid dynamics model. These trajectories and vapour concentrations were then used as an input for the cloud parcel model to simulate mass transfer kinetics of water and semivolatiles between aerosol particles and the gas phase. Two different questions were studied: (1) how big a fraction of semivolatiles is evaporated from particles after entering but before particle activation in the DMT-CCN counter? (2) How much can the CCN activity be increased due to condensation of semivolatiles prior to the maximum water supersaturation in the case of high semivolatile concentration in the gas phase? Both experimental and modelling results show that the evaporation of ammonia and nitric acid from ammonium nitrate particles causes a 10 to 15 nm decrease to the critical particle size in supersaturations between 0.1% and 0.7%. On the other hand, the modelling results also show that condensation of nitric acid or similar vapour can increase the CCN activity of nonvolatile aerosol particles, but a very high gas phase concentration (as compared to typical ambient conditions) would be needed. Overall, it is more likely that the CCN activity of semivolatile aerosol is underestimated than overestimated in the measurements conducted in ambient conditions.

scholarly journals The effect of phase partitioning of semivolatile compounds on the measured CCN activity of aerosol particles

2013 ◽  
Vol 6 (5) ◽  
pp. 8413-8433 ◽  
Author(s):  
S. Romakkaniemi ◽  
A. Jaatinen ◽  
A. Laaksonen ◽  
A. Nenes ◽  
T. Raatikainen
Keyword(s):  
Ammonium Nitrate ◽  
Gas Phase ◽  
Aerosol Particles ◽  
Test Compound ◽  
Ambient Conditions ◽  
Compound A ◽  
Phase Partitioning ◽  
Maximum Water ◽  
Kinetics Of ◽  
Ccn Activity

Abstract. The effect of inorganic semivolatile aerosol compounds on the CCN activity of aerosol particles was studied by using a computational model for a DMT-CCN counter, a cloud parcel model for condensation kinetics and experiments to quantify the modelled results. Concentrations of water vapour and semivolatiles as well as aerosol trajectories in the CCN column were calculated by a computational fluid dynamics model. These trajectories and vapour concentrations were then used as an input for the cloud parcel model to simulate mass transfer kinetics of water and semivolatiles between aerosol particles and the gas phase. Two different questions were studied: (1) how big fraction of semivolatiles is evaporated from particles before activation in the CCN counter? (2) How much the CCN activity can be increased due to condensation of semivolatiles prior to the maximum water supersaturation in the case of high semivolatile concentration in the gas phase? The results show that, to increase the CCN activity of aerosol particles, a very high gas phase concentration (as compared to typical ambient conditions) is needed. We used nitric acid as a test compound. A concentration of several ppb or higher is needed for measurable effect. In the case of particle evaporation, we used ammonium nitrate as a test compound and found that it partially evaporates before maximum supersaturation is reached in the CCN counter, thus causing an underestimation of CCN activity. The effect of evaporation is clearly visible in all supersaturations, leading to an underestimation of the critical dry diameter by 10 to 15 nanometres in the case of ammonium nitrate particles in different supersaturations. This result was also confirmed by measurements in supersaturations between 0.1 and 0.7%.

The effect of atmospheric nitric acid vapor on cloud condensation nucleus activation

1993 ◽  
Vol 98 (D12) ◽  
pp. 22949 ◽  
Author(s):  
M. Kulmala ◽  
A. Laaksonen ◽  
P. Korhonen ◽  
T. Vesala ◽  
T. Ahonen ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Condensation Nucleus ◽  
Cloud Condensation Nucleus ◽  
Acid Vapor

scholarly journals A single parameter representation of hygroscopic growth and cloud condensation nucleus activity – Part 2: Including solubility

2008 ◽  
Vol 8 (20) ◽  
pp. 6273-6279 ◽  
Author(s):  
M. D. Petters ◽  
S. M. Kreidenweis
Keyword(s):  
Unit Volume ◽  
Condensation Nucleus ◽  
Single Parameter ◽  
Saturated Solution ◽  
Cloud Condensation Nucleus ◽  
Hygroscopic Growth ◽  
Solubility In Water ◽  
Parameter Representation ◽  
Model Complex ◽  
Ccn Activity

Abstract. The ability of a particle to serve as a cloud condensation nucleus in the atmosphere is determined by its size, hygroscopicity and its solubility in water. Usually size and hygroscopicity alone are sufficient to predict CCN activity. Single parameter representations for hygroscopicity have been shown to successfully model complex, multicomponent particles types. Under the assumption of either complete solubility, or complete insolubility of a component, it is not necessary to explicitly include that component's solubility into the single parameter framework. This is not the case if sparingly soluble materials are present. In this work we explicitly account for solubility by modifying the single parameter equations. We demonstrate that sensitivity to the actual value of solubility emerges only in the regime of 2×10−1–5×10−4, where the solubility values are expressed as volume of solute per unit volume of water present in a saturated solution. Compounds that do not fall inside this sparingly soluble envelope can be adequately modeled assuming they are either infinitely soluble in water or completely insoluble.

scholarly journals Widening the gap between measurement and modelling of secondary organic aerosol properties?

2010 ◽  
Vol 10 (6) ◽  
pp. 2577-2593 ◽  
Author(s):  
N. Good ◽  
D. O. Topping ◽  
J. Duplissy ◽  
M. Gysel ◽  
N. K. Meyer ◽  
...  
Keyword(s):  
Surface Tension ◽  
Water Activity ◽  
Condensation Nucleus ◽  
Organic Aerosol ◽  
Solute Concentration ◽  
Complex Model ◽  
Cloud Condensation Nucleus ◽  
Saturated Water ◽  
Cloud Activation ◽  
Ccn Activity

Abstract. The link between measured sub-saturated hygroscopicity and cloud activation potential of secondary organic aerosol particles produced by the chamber photo-oxidation of α-pinene in the presence or absence of ammonium sulphate seed aerosol was investigated using two models of varying complexity. A simple single hygroscopicity parameter model and a more complex model (incorporating surface effects) were used to assess the detail required to predict the cloud condensation nucleus (CCN) activity from the sub-saturated water uptake. Sub-saturated water uptake measured by three hygroscopicity tandem differential mobility analyser (HTDMA) instruments was used to determine the water activity for use in the models. The predicted CCN activity was compared to the measured CCN activation potential using a continuous flow CCN counter. Reconciliation using the more complex model formulation with measured cloud activation could be achieved widely different assumed surface tension behavior of the growing droplet; this was entirely determined by the instrument used as the source of water activity data. This unreliable derivation of the water activity as a function of solute concentration from sub-saturated hygroscopicity data indicates a limitation in the use of such data in predicting cloud condensation nucleus behavior of particles with a significant organic fraction. Similarly, the ability of the simpler single parameter model to predict cloud activation behaviour was dependent on the instrument used to measure sub-saturated hygroscopicity and the relative humidity used to provide the model input. However, agreement was observed for inorganic salt solution particles, which were measured by all instruments in agreement with theory. The difference in HTDMA data from validated and extensively used instruments means that it cannot be stated with certainty the detail required to predict the CCN activity from sub-saturated hygroscopicity. In order to narrow the gap between measurements of hygroscopic growth and CCN activity the processes involved must be understood and the instrumentation extensively quality assured. It is impossible to say from the results presented here due to the differences in HTDMA data whether: i) Surface tension suppression occurs ii) Bulk to surface partitioning is important iii) The water activity coefficient changes significantly as a function of the solute concentration.

Hygroscopicity and cloud condensation nucleus activity of marine aerosol particles over the western North Pacific

2011 ◽  
Vol 116 (D6) ◽  
Author(s):  
Michihiro Mochida ◽  
Chiharu Nishita-Hara ◽  
Hiroshi Furutani ◽  
Yuzo Miyazaki ◽  
Jinyoung Jung ◽  
...  
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Aerosol Particles ◽  
Condensation Nucleus ◽  
Cloud Condensation Nucleus ◽  
Marine Aerosol

scholarly journals Relating particle hygroscopicity and CCN activity to chemical composition during the HCCT-2010 field campaign

2013 ◽  
Vol 13 (16) ◽  
pp. 7983-7996 ◽  
Author(s):  
Z. J. Wu ◽  
L. Poulain ◽  
S. Henning ◽  
K. Dieckmann ◽  
W. Birmili ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Cloud Condensation Nuclei ◽  
Condensation Nucleus ◽  
Sampling Period ◽  
Cloud Condensation Nucleus ◽  
Mountain Range ◽  
Mixing Rule ◽  
Hygroscopic Growth ◽  
Parameter Values ◽  
Ccn Activity

Abstract. Particle hygroscopic growth at 90% RH (relative humidity), cloud condensation nuclei (CCN) activity, and size-resolved chemical composition were concurrently measured in the Thüringer Wald mid-level mountain range in central Germany in the fall of 2010. The median hygroscopicity parameter values, κ, of 50, 75, 100, 150, 200, and 250 nm particles derived from hygroscopicity measurements are respectively 0.14, 0.14, 0.17, 0.21, 0.24, and 0.28 during the sampling period. The closure between HTDMA (Hygroscopicity Tandem Differential Mobility Analyzers)-measured (κHTDMA) and chemical composition-derived (κchem) hygroscopicity parameters was performed based on the Zdanovskii–Stokes–Robinson (ZSR) mixing rule. Using size-averaged chemical composition, the κ values are substantially overpredicted (30 and 40% for 150 and 100 nm particles). Introducing size-resolved chemical composition substantially improved closure. We found that the evaporation of NH4NO3, which may happen in a HTDMA system, could lead to a discrepancy in predicted and measured particle hygroscopic growth. The hygroscopic parameter of the organic fraction, κorg, is positively correlated with the O : C ratio (κorg = 0.19 × (O : C) − 0.03). Such correlation is helpful to define the κorg value in the closure study. κ derived from CCN measurement was around 30% (varied with particle diameters) higher than that determined from particle hygroscopic growth measurements (here, hydrophilic mode is considered only). This difference might be explained by the surface tension effects, solution non-ideality, gas-particle partitioning of semivolatile compounds, and the partial solubility of constituents or non-dissolved particle matter. Therefore, extrapolating from HTDMA data to properties at the point of activation should be done with great care. Finally, closure study between CCNc (cloud condensation nucleus counter)-measured (κCCN) and chemical composition (κCCN, chem) was performed using CCNc-derived κ values for individual components. The results show that the κCCN can be well predicted using particle size-resolved chemical composition and the ZSR mixing rule.

scholarly journals Droplet activation, separation, and compositional analysis: laboratory studies and atmospheric measurements

2011 ◽  
Vol 4 (1) ◽  
pp. 691-713 ◽  
Author(s):  
N. Hiranuma ◽  
M. Kohn ◽  
M. S. Pekour ◽  
D. A. Nelson ◽  
J. E. Shilling ◽  
...  
Keyword(s):  
Ammonium Sulfate ◽  
Droplet Size ◽  
Aerosol Particles ◽  
Condensation Nucleus ◽  
Polystyrene Latex ◽  
Cloud Condensation Nucleus ◽  
Particle Analysis ◽  
Laser Mass Spectrometry ◽  
Atmospheric Measurements ◽  
Virtual Impactor

Abstract. Droplets produced in a cloud condensation nucleus chamber as a function of supersaturation have been separated from unactivated aerosol particles using counterflow virtual impaction. Residual material after droplets were evaporated was chemically analyzed with an Aerodyne Aerosol Mass Spectrometer and the Particle Analysis by Laser Mass Spectrometry instrument. Experiments were initially conducted to verify activation conditions for monodisperse ammonium sulfate particles and to determine the resulting droplet size distribution as a function of supersaturation. Based on the observed droplet size, the counterflow virtual impactor cut-size was set to differentiate droplets from unactivated interstitial particles. Validation experiments were then performed to verify that only droplets with sufficient size passed through the counterflow virtual impactor for subsequent analysis. A two-component external mixture of monodisperse particles was also exposed to a supersaturation which would activate one of the types (ammonium sulfate) but not the other (polystyrene latex spheres). The mass spectrum observed after separation indicated only the former, validating separation of droplets from unactivated particles. Results from atmospheric measurements using this technique indicate that aerosol particles often activate predominantly as a function of particle size. Chemical composition is not irrelevant, however, and we observed enhancement of sulfate in droplet residuals using single particle analysis.

scholarly journals Airborne and ground-based observations of ammonium nitrate dominated aerosols in a shallow boundary layer during intense winter pollution episodes in northern Utah

2018 ◽  
Author(s):  
Alessandro Franchin ◽  
Dorothy L. Fibiger ◽  
Lexie Goldberger ◽  
Erin E. McDuffie ◽  
Alexander Moravek ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Nitric Acid ◽  
Chemical Composition ◽  
Ammonium Nitrate ◽  
Gas Phase ◽  
Aerosol Mass ◽  
Northern Utah ◽  
Total Ammonium ◽  
Pollution Episodes ◽  
Mass Concentrations

Abstract. Airborne and ground-based measurements of aerosol concentrations, chemical composition and gas phase precursors were obtained in three valleys in northern Utah (U.S.A.). The measurements were part of the Utah Winter Fine Particulate Study (UWFPS) that took place in January–February, 2017. Total aerosol mass concentrations of PM1 were measured from a Twin Otter aircraft, with an Aerosol Mass Spectrometer (AMS). PM1 concentrations ranged from less than 2 μg m−3 during clean periods to over 100 μg m−3 during the most polluted episodes, consistent with PM2.5 total mass concentrations measured concurrently at ground sites. Across the entire region, increases in total aerosol mass above ~ 2 μg m−3 were associated with increases in the ammonium nitrate mass fraction, clearly indicating that the highest aerosol mass loadings in the region were predominantly attributable to an increase in ammonium nitrate. The chemical composition was regionally homogenous for total aerosol mass concentrations above 17.5 μg m−3, with 74 ± 5 % (average ± standard deviation) ammonium nitrate, 18 ± 3 % organic material, 6 ± 3 % ammonium sulfate, and 2 ± 2 % ammonium chloride. Vertical profiles of aerosol mass and volume in the region showed variable concentrations with height in the polluted boundary layer. Higher average mass concentrations were observed within the first few hundred meters above ground level in all three valleys during pollution episodes. Gas phase measurements of nitric acid (HNO3) and ammonia (NH3) during the pollution episodes revealed that in Cache and Utah Valley, partitioning of inorganic semi-volatiles to the aerosol phase was usually limited by the amount of gas phase nitric acid, with NH3 being in excess. The inorganic species were compared with the ISORROPIA thermodynamic model. Total inorganic aerosol mass concentrations were calculated for various decreases of total nitrate and total ammonium. For pollution episodes, our simulations of a 50 % decrease in total nitrate lead to a 46 ± 3 % decrease in total PM1 mass. A simulated 50 % decrease in total ammonium lead to a 36 ± 17% µg m−3 in total PM1 mass, over the entire area of the study. Despite some differences among different locations, our results also showed a higher sensitivity to decreasing nitric acid concentrations and the importance of ammonia at the lowest total nitrate conditions. In the Salt Lake Valley, both HNO3 and NH3 concentrations controlled aerosol formation.

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