scholarly journals Ice nucleation by viruses and their potential for cloud glaciation

2021 ◽  
Vol 18 (14) ◽  
pp. 4431-4444
Author(s):  
Michael P. Adams ◽  
Nina S. Atanasova ◽  
Svetlana Sofieva ◽  
Janne Ravantti ◽  
Aino Heikkinen ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Ice Nucleation ◽  
Marine Atmosphere ◽  
Biological Origin ◽  
Virus Particles ◽  
Particle Population ◽  
Minor Contribution ◽  
Different Types ◽  
A Minor ◽  
The Impact

Abstract. In order to effectively predict the formation of ice in clouds we need to know which subsets of aerosol particles are effective at nucleating ice, how they are distributed and where they are from. A large proportion of ice-nucleating particles (INPs) in many locations are likely of biological origin, and some INPs are extremely small, being just tens of nanometres in size. The identity and sources of such INPs are not well characterized. Here, we show that several different types of virus particles can nucleate ice, with up to about 1 in 20 million virus particles able to nucleate ice at −20 ∘C. In terms of the impact on cloud glaciation, the ice-nucleating ability (the fraction which are ice nucleation active as a function of temperature) taken together with typical virus particle concentrations in the atmosphere leads to the conclusion that virus particles make a minor contribution to the atmospheric ice-nucleating particle population in the terrestrial-influenced atmosphere. However, they cannot be ruled out as being important in the remote marine atmosphere. It is striking that virus particles have an ice-nucleating activity, and further work should be done to explore other types of viruses for both their ice-nucleating potential and to understand the mechanism by which viruses nucleate ice.

scholarly journals Ice nucleation by viruses and their potential for cloud glaciation

2021 ◽  
Author(s):  
Michael P. Adams ◽  
Nina S. Atanasova ◽  
Svetlana Sofieva ◽  
Janne Ravantti ◽  
Aino Heikkinen ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Ice Nucleation ◽  
Marine Atmosphere ◽  
Biological Origin ◽  
Virus Particles ◽  
Particle Population ◽  
Minor Contribution ◽  
Different Types ◽  
A Minor ◽  
The Impact

Abstract. In order to effectively predict the formation of ice in clouds we need to know which subsets of aerosol particles are effective at nucleating ice, how they are distributed and where they are from. A large proportion of ice-nucleating particles (INPs) in many locations are likely of biological origin, and some INPs are extremely small being just tens of nanometers in size. The identity and sources of such INPs are not well characterized. Here, we show that several different types of virus particles can nucleate ice, with up to about one in twenty million virus particles able to nucleate ice at −20 °C. In terms of the impact on cloud glaciation, the ice-nucleating ability (the fraction which are ice nucleation active as a function of temperature) taken together with typical virus particle concentrations in the atmosphere lead to the conclusion that virus particles make a minor contribution to the atmospheric ice-nucleating particle population in the terrestrial influenced atmosphere. However, they cannot be ruled out as being important in the remote marine atmosphere. It is striking that virus particles have an ice-nucleating activity and further work should be done to explore other types of viruses for both their ice-nucleating potential and to understand the mechanism by which viruses nucleate ice.

scholarly journals The impact of aerosol hygroscopic growth on the single-scattering albedo and its application on the NO<sub>2</sub> photolysis rate coefficient

2014 ◽  
Vol 14 (11) ◽  
pp. 16351-16386
Author(s):  
J. C. Tao ◽  
C. S. Zhao ◽  
N. Ma ◽  
P. F. Liu
Keyword(s):  
Boundary Layer ◽  
Aerosol Particle ◽  
Rate Coefficient ◽  
Aerosol Particles ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Hygroscopic Growth ◽  
Particle Population ◽  
The Impact ◽  
Upper Boundary

Abstract. Hygroscopic growth of aerosol particles can significantly affect their single-scattering albedo (ω), and consequently alters the aerosol effect on tropospheric photochemistry. In this study, the impact of aerosol hygroscopic growth on the ω and its application on NO2 photolysis rate coefficient (JNO2) are investigated for a typical aerosol particle population in the North China Plain (NCP). The variations of aerosol optical properties with relative humidity (RH) are calculated using a Mie-theory aerosol optical model, on the basis of field measurements of number size distribution and hygroscopic growth factor from 2009 HaChi (Haze in China) project. Results demonstrate that ambient ω has pronounced diurnal patterns and is highly sensitive to the ambient RHs. Ambient ω in the NCP can be described by a dry state ω value of 0.863, increasing with the RH following a characteristic RH dependence curve. The Monte Carlo simulation shows that the uncertainty of ω from the propagation of uncertainties in the input parameters decreases from 0.03 (at dry state) to 0.01 (RHs > 90%). The impact of hygroscopic growth on ω is further applied in the calculation of the radiative transfer process. Hygroscopic growth of the studied aerosol particle population generally inhibits the photolysis of NO2 at the ground level, whereas accelerates it above the upper boundary layer. Compared with dry state, the calculated JNO2 at RH of 98% at the height of 1 km increases by 30.4%, because of the enhancement of ultraviolet radiation by the humidified scattering-dominant aerosol particles. The increase of JNO2 due to the aerosol hygroscopic growth above the upper boundary layer may affect the tropospheric photochemical processes and this needs to be taken into account in the atmospheric chemical models.

scholarly journals Ice nucleation by combustion ash particles at conditions relevant to mixed-phase clouds

2014 ◽  
Vol 14 (21) ◽  
pp. 28845-28883
Author(s):  
N. S. Umo ◽  
B. J. Murray ◽  
M. T. Baeza-Romero ◽  
J. M. Jones ◽  
A. R. Lea-Langton ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Coal Fly Ash ◽  
Aerosol Particles ◽  
Bottom Ash ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
Dust Particles ◽  
Cloud Properties ◽  
Mixed Phase Clouds ◽  
The Impact

Abstract. Ice nucleating particles can modify cloud properties with implications for climate and the hydrological cycle; hence, it is important to understand which aerosol particle types nucleate ice and how efficiently they do so. It has been shown that aerosol particles such as natural dusts, volcanic ash, bacteria and pollen can act as ice nucleating particles, but the ice nucleating ability of combustion ashes has not been studied. Combustion ashes are major by-products released during the combustion of solid fuels and a significant amount of these ashes are emitted into the atmosphere either during combustion or via aerosolization of bottom ashes. Here, we show that combustion ashes (coal fly ash, wood bottom ash, domestic bottom ash, and coal bottom ash) nucleate ice in the immersion mode at conditions relevant to mixed-phase clouds. Hence, combustion ashes could play an important role in primary ice formation in mixed-phase clouds, especially in clouds that are formed near the emission source of these aerosol particles. In order to quantitatively assess the impact of combustion ashes on mixed-phase clouds, we propose that the atmospheric abundance of combustion ashes should be quantified since up to now they have mostly been classified together with mineral dust particles. Also, in reporting ice residue compositions, a distinction should be made between natural mineral dusts and combustion ashes in order to quantify the contribution of combustion ashes to atmospheric ice nucleation.

scholarly journals Ice nucleation ability of ammonium sulfate aerosol particles internally mixed with secondary organics

2021 ◽  
Vol 21 (13) ◽  
pp. 10779-10798
Author(s):  
Barbara Bertozzi ◽  
Robert Wagner ◽  
Junwei Song ◽  
Kristina Höhler ◽  
Joschka Pfeifer ◽  
...  
Keyword(s):  
Organic Matter ◽  
Ammonium Sulfate ◽  
Active Sites ◽  
Aerosol Particles ◽  
Particle Morphology ◽  
Organic Coating ◽  
Ice Nucleation ◽  
Cloud Models ◽  
Organic Particles ◽  
The Impact

Abstract. The abundance of aerosol particles and their ability to catalyze ice nucleation are key parameters to correctly understand and describe the aerosol indirect effect on the climate. Cirrus clouds strongly influence the Earth's radiative budget, but their effect is highly sensitive to their formation mechanism, which is still poorly understood. Sulfate and organics are among the most abundant aerosol components in the troposphere and have also been found in cirrus ice crystal residuals. Most of the studies on ice nucleation at cirrus cloud conditions looked at either purely inorganic or purely organic particles. However, particles in the atmosphere are mostly found as internal mixtures, the ice nucleation ability of which is not yet fully characterized. In this study, we investigated the ice nucleation ability of internally mixed particles composed of crystalline ammonium sulfate (AS) and secondary organic material (SOM) at temperatures between −50 and −65 ∘C. The SOM was generated from the ozonolysis of α-pinene. The experiments were conducted in a large cloud chamber, which also allowed us to simulate various aging processes that the particles may experience during their transport in the atmosphere, like cloud cycling and redistribution of the organic matter. We found that the ice nucleation ability of the mixed AS / SOM particles is strongly dependent on the particle morphology. Small organic mass fractions of 5 wt %–8 wt % condensed on the surface of AS crystals are sufficient to completely suppress the ice nucleation ability of the inorganic component, suggesting that the organic coating is evenly distributed on the surface of the seed particles. In this case, the ice nucleation onset increased from a saturation ratio with respect to ice Sice∼1.30 for the pure AS crystals to ≥1.45 for the SOM-coated AS crystals. However, if such SOM-coated AS crystals are subjected to the mentioned aging processes, they show an improved ice nucleation ability with the ice nucleation onset at Sice∼1.35. We suggest that the aging processes change the particle morphology. The organic matter might redistribute on the surface to form a partially engulfed structure, where the ice-nucleation-active sites of the AS crystals are no longer completely masked by the organic coating, or the morphology of the organic coating layer might transform from a compact to a porous structure. Our results underline the complexity in representing the ice nucleation ability of internally mixed particles in cloud models. They also demonstrate the need to further investigate the impact of atmospheric aging and cloud processing on the morphology and related ice nucleation ability of internally mixed particles.

scholarly journals Ice nucleation by combustion ash particles at conditions relevant to mixed-phase clouds

2015 ◽  
Vol 15 (9) ◽  
pp. 5195-5210 ◽  
Author(s):  
N. S. Umo ◽  
B. J. Murray ◽  
M. T. Baeza-Romero ◽  
J. M. Jones ◽  
A. R. Lea-Langton ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Coal Fly Ash ◽  
Aerosol Particles ◽  
Bottom Ash ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
Dust Particles ◽  
Cloud Properties ◽  
Mixed Phase Clouds ◽  
The Impact

Abstract. Ice-nucleating particles can modify cloud properties with implications for climate and the hydrological cycle; hence, it is important to understand which aerosol particle types nucleate ice and how efficiently they do so. It has been shown that aerosol particles such as natural dusts, volcanic ash, bacteria and pollen can act as ice-nucleating particles, but the ice-nucleating ability of combustion ashes has not been studied. Combustion ashes are major by-products released during the combustion of solid fuels and a significant amount of these ashes are emitted into the atmosphere either during combustion or via aerosolization of bottom ashes. Here, we show that combustion ashes (coal fly ash, wood bottom ash, domestic bottom ash, and coal bottom ash) nucleate ice in the immersion mode at conditions relevant to mixed-phase clouds. Hence, combustion ashes could play an important role in primary ice formation in mixed-phase clouds, especially in clouds that are formed near the emission source of these aerosol particles. In order to quantitatively assess the impact of combustion ashes on mixed-phase clouds, we propose that the atmospheric abundance of combustion ashes should be quantified since up to now they have mostly been classified together with mineral dust particles. Also, in reporting ice residue compositions, a distinction should be made between natural mineral dusts and combustion ashes in order to quantify the contribution of combustion ashes to atmospheric ice nucleation.

scholarly journals The impact of aerosol hygroscopic growth on the single-scattering albedo and its application on the NO<sub>2</sub> photolysis rate coefficient

2014 ◽  
Vol 14 (22) ◽  
pp. 12055-12067 ◽  
Author(s):  
J. C. Tao ◽  
C. S. Zhao ◽  
N. Ma ◽  
P. F. Liu
Keyword(s):  
Boundary Layer ◽  
Aerosol Particle ◽  
Rate Coefficient ◽  
Aerosol Particles ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Hygroscopic Growth ◽  
Particle Population ◽  
Photolysis Rate ◽  
The Impact

Abstract. Hygroscopic growth of aerosol particles can significantly affect their single-scattering albedo (ω), and consequently alters the aerosol effect on tropospheric photochemistry. In this study, the impact of aerosol hygroscopic growth on ω and its application to the NO2 photolysis rate coefficient (JNO2) are investigated for a typical aerosol particle population in the North China Plain (NCP). The variations of aerosol optical properties with relative humidity (RH) are calculated using a Mie theory aerosol optical model, on the basis of field measurements of number–size distribution and hygroscopic growth factor (at RH values above 90%) from the 2009 HaChi (Haze in China) project. Results demonstrate that ambient ω has pronouncedly different diurnal patterns from ω measured at dry state, and is highly sensitive to the ambient RHs. Ambient ω in the NCP can be described by a dry state ω value of 0.863, increasing with the RH following a characteristic RH dependence curve. A Monte Carlo simulation shows that the uncertainty of ω from the propagation of uncertainties in the input parameters decreases from 0.03 (at dry state) to 0.015 (RHs > 90%). The impact of hygroscopic growth on ω is further applied in the calculation of the radiative transfer process. Hygroscopic growth of the studied aerosol particle population generally inhibits the photolysis of NO2 at the ground level, whereas accelerates it above the moist planetary boundary layer. Compared with dry state, the calculated JNO2 at RH of 98% at the height of 1 km increases by 30.4%, because of the enhancement of ultraviolet radiation by the humidified scattering-dominant aerosol particles. The increase of JNO2 due to the aerosol hygroscopic growth above the upper boundary layer may affect the tropospheric photochemical processes and this needs to be taken into account in the atmospheric chemical models.

scholarly journals Ice nucleation ability of Ammonium Sulfate aerosol particles internally mixed with Secondary Organics

2021 ◽  
Author(s):  
Barbara Bertozzi ◽  
Robert Wagner ◽  
Kristina Höhler ◽  
Joschka Pfeifer ◽  
Harald Saathoff ◽  
...  
Keyword(s):  
Organic Matter ◽  
Ammonium Sulfate ◽  
Active Sites ◽  
Aerosol Particles ◽  
Particle Morphology ◽  
Organic Coating ◽  
Ice Nucleation ◽  
Shell Morphology ◽  
Cloud Models ◽  
The Impact

Abstract. The abundance of aerosol particles and their ability to catalyze ice nucleation are key parameters to correctly understand and describe the aerosol indirect effect on the climate. Cirrus clouds strongly influence the Earth's radiative budget, but their effect is highly sensitive to their formation mechanism, which is still poorly understood. Sulfate and organics are among the most abundant aerosol components in the troposphere and have also been found in cirrus ice crystal residuals. Most of the studies on ice nucleation at cirrus cloud conditions looked at either purely inorganic or purely organic particles. However, particles in the atmosphere are mostly found as internal mixtures, the ice nucleation ability of which is not yet fully characterized. In this study, we investigated the ice nucleation ability of internally mixed particles composed of crystalline ammonium sulfate (AS) and secondary organic material (SOM) at temperatures between −50 °C and −65 °C. The SOM was generated from the ozonolysis of α-pinene. The experiments were conducted in a large cloud chamber, which also allowed to simulate various aging processes that the particles may experience during their transport in the atmosphere, like cloud cycling and redistribution of the organic matter. We found that the ice nucleation ability of the mixed AS/SOM particles is strongly dependent on the particle morphology. If the organic matter is evenly distributed around the AS crystals in a core-shell morphology, small organic mass fractions of 5–8 wt% are sufficient to completely mask the heterogeneous ice nucleation ability of the inorganic core. In this case, the ice nucleation onset increased from a saturation ratio with respect to ice Sice ~ 1.30 for the pure AS crystals to ≥ 1.45 for the SOM-coated AS crystals. However, if such SOM-coated AS crystals are subjected to the mentioned aging processes, they show an improved ice nucleation ability with the ice nucleation onset at Sice ~ 1.35. We suggest that the aging processes change the particle morphology. The organic matter might redistribute on the surface to form a partially engulfed structure, where the ice-active sites of the AS crystals are no longer completely masked by the organic coating, or the morphology of the organic coating layer might transform from a compact to a porous structure. Our results underline the complexity to represent the ice nucleation ability of internally mixed particles in cloud models. They also demonstrate the need to further investigate the impact of atmospheric aging and cloud processing on the morphology and related ice nucleation ability of internally mixed particles.

scholarly journals Model Development for Refining Rates in Oxygen Steelmaking: Impact and Slag-Metal Bulk Zones

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 309 ◽  
Author(s):  
Ameya Kadrolkar ◽  
Neslihan Dogan
Keyword(s):  
Current Model ◽  
Model Development ◽  
Water Model ◽  
Slag Formation ◽  
Surface Renewal ◽  
New Approach ◽  
Minor Contribution ◽  
Oxygen Steelmaking ◽  
A Minor ◽  
The Impact

A new approach has been adopted to predict the contribution of the impact and slag-metal bulk zones to the refining rates of impurities in a top blown oxygen steelmaking process. The knowledge pertaining to the behavior of top-jets and bottom stirring plumes (water model and industrial studies) was adapted. For the impact zone, the surface renewal generated by the top jet as well as bottom stirring plumes is incorporated in the current model, whereas in the case of slag-metal bulk zones the surface renewal is caused solely by the bottom stirring plumes. This approach helped in achieving a more explicit use of process parameters in quantifying the slag formation. The results suggest a minor contribution of these two zones to the overall refining of impurities throughout the oxygen blow.

scholarly journals Uptake selectivity of Methanesulfonic Acid (MSA) on fine particles over polynya regions of the Ross Sea, Antarctica

2019 ◽  
Author(s):  
Jinpei Yan ◽  
Jinyoung Joung ◽  
Miming Zhang ◽  
Federico Bianchi ◽  
Yee Jun Tham ◽  
...  
Keyword(s):  
Fine Particles ◽  
Ross Sea ◽  
Aerosol Particles ◽  
Methanesulfonic Acid ◽  
Chemical Properties ◽  
Chemical Compositions ◽  
Marine Atmosphere ◽  
Particle Population ◽  
Hydrophobic Particles ◽  
Major Route

Abstract. The uptake of methanesulfonic acid (MSA) on existing particles is a major route of the particulate MSA formation, however, MSA uptake on different particles is still lack of knowledge. Characteristics of MSA uptake on different aerosol particles were investigated in polynya regions of the Ross Sea, Antarctica. Particulate MSA mass concentrations, as well as aerosol populations and size distributions, were observed simultaneously for the first time to access the uptake of MSA on different particles. The results showed that MSA mass concentration did not always reflect MSA particle population in the marine atmosphere. MSA uptake on aerosol particles increased the particle size and changed aerosol chemical compositions, but did not increase the particle population. The uptake rates of MSA on existing particles were significantly influenced by aerosol chemical properties. The favor uptake of MSA occurred on the sea salt particles, as MSA-Na and MSA-Mg particles were abundant in the Na and Mg particles, accounting for 0.43 ± 0.21 and 0.41 ± 0.20 of the total Na and Mg particles, respectively. However, acidic and hydrophobic particles suppressed the MSA uptake, as MSA-EC and MSA-SO42− accounted only 0.24 ± 0.68 and 0.26 ± 0.47 of the total EC and SO42− particles, respectively. The results extended the knowledge of the formation and environmental behavior of MSA in the marine atmosphere.

Quota Women Are Threatening to Men

2017 ◽  
Vol 76 (3) ◽  
pp. 107-116 ◽  
Author(s):  
Klea Faniko ◽  
Till Burckhardt ◽  
Oriane Sarrasin ◽  
Fabio Lorenzi-Cioldi ◽  
Siri Øyslebø Sørensen ◽  
...  
Keyword(s):  
Decision Making ◽  
Organizational Performance ◽  
Gender Stereotypes ◽  
Perceived Threat ◽  
Preferential Treatment ◽  
Public Sector Employees ◽  
Different Types ◽  
Low Levels ◽  
Women In Decision Making ◽  
The Impact

Abstract. Two studies carried out among Albanian public-sector employees examined the impact of different types of affirmative action policies (AAPs) on (counter)stereotypical perceptions of women in decision-making positions. Study 1 (N = 178) revealed that participants – especially women – perceived women in decision-making positions as more masculine (i.e., agentic) than feminine (i.e., communal). Study 2 (N = 239) showed that different types of AA had different effects on the attribution of gender stereotypes to AAP beneficiaries: Women benefiting from a quota policy were perceived as being more communal than agentic, while those benefiting from weak preferential treatment were perceived as being more agentic than communal. Furthermore, we examined how the belief that AAPs threaten men’s access to decision-making positions influenced the attribution of these traits to AAP beneficiaries. The results showed that men who reported high levels of perceived threat, as compared to men who reported low levels of perceived threat, attributed more communal than agentic traits to the beneficiaries of quotas. These findings suggest that AAPs may have created a backlash against its beneficiaries by emphasizing gender-stereotypical or counterstereotypical traits. Thus, the framing of AAPs, for instance, as a matter of enhancing organizational performance, in the process of policy making and implementation, may be a crucial tool to countering potential backlash.

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