scholarly journals A new multicomponent heterogeneous ice nucleation model and its application to Snomax bacterial particles and a Snomax–illite mineral particle mixture

2017 ◽  
Vol 17 (22) ◽  
pp. 13545-13557 ◽  
Author(s):  
Hassan Beydoun ◽  
Michael Polen ◽  
Ryan C. Sullivan
Keyword(s):  
Biological Material ◽  
Cloud Microphysics ◽  
Ice Nucleation ◽  
Freezing Behavior ◽  
Dust Particles ◽  
Critical Surface ◽  
Wide Range ◽  
Nucleation Model ◽  
Immersion Freezing ◽  
Heterogeneous Ice Nucleation

Abstract. Some biological particles, such as Snomax, are very active ice nucleating particles, inducing heterogeneous freezing in supercooled water at temperatures above −15 and up to −2 °C. Despite their exceptional freezing abilities, large uncertainties remain regarding the atmospheric abundance of biological ice nucleating particles, and their contribution to atmospheric ice nucleation. It has been suggested that small biological ice nucleating macromolecules or fragments can be carried on the surfaces of dust and other atmospheric particles. This could combine the atmospheric abundance of dust particles with the ice nucleating strength of biological material to create strongly enhanced and abundant ice nucleating surfaces in the atmosphere, with significant implications for the budget and distribution of atmospheric ice nucleating particles, and their consequent effects on cloud microphysics and mixed-phase clouds. The new critical surface area g framework that was developed by Beydoun et al. (2016) is extended to produce a heterogeneous ice nucleation mixing model that can predict the freezing behavior of multicomponent particle surfaces immersed in droplets. The model successfully predicts the immersion freezing properties of droplets containing Snomax bacterial particles across a mass concentration range of 7 orders of magnitude, by treating Snomax as comprised of two distinct distributions of heterogeneous ice nucleating activity. Furthermore, the model successfully predicts the immersion freezing behavior of a low-concentration mixture of Snomax and illite mineral particles, a proxy for the biological material–dust (bio-dust) mixtures observed in atmospheric aerosols. It is shown that even at very low Snomax concentrations in the mixture, droplet freezing at higher temperatures is still determined solely by the second less active and more abundant distribution of heterogeneous ice nucleating activity of Snomax, while freezing at lower temperatures is determined solely by the heterogeneous ice nucleating activity of pure illite. This demonstrates that in this proxy system, biological ice nucleating particles do not compromise their ice nucleating activity upon mixing with dust and no new range of intermediary freezing temperatures associated with the mixture of ice nucleating particles of differing activities is produced. The study is the first to directly examine the freezing behavior of a mixture of Snomax and illite and presents the first multicomponent ice nucleation model experimentally evaluated using a wide range of ice nucleating particle concentration mixtures in droplets.

scholarly journals A new multi-component heterogeneous ice nucleation model and its application to Snomax bacterial particles and a Snomax-illte mineral particle mixture

2017 ◽  
Author(s):  
Hassan Beydoun ◽  
Michael Polen ◽  
Ryan C. Sullivan
Keyword(s):  
Cloud Microphysics ◽  
Ice Nucleation ◽  
Freezing Behavior ◽  
Dust Particles ◽  
Mineral Particle ◽  
Critical Surface ◽  
Wide Range ◽  
Nucleation Model ◽  
Immersion Freezing ◽  
Heterogeneous Ice Nucleation

Abstract. Some biological particles, such as Snomax, are very active ice nucleating particles, inducing heterogeneous freezing in supercooled water at temperatures above −15° C and up to −2° C. Despite their exceptional freezing abilities, large uncertainties remain regarding the atmospheric abundance of biological ice nucleating particles, and their contribution to atmospheric ice nucleation. It has been suggested that small biological ice nucleating macromolecules or fragments can be carried on the surfaces of dust and other atmospheric particles. This could combine the atmospheric abundance of dust particles with the ice nucleating strength of biological material to create strongly enhanced and abundant ice nucleating surfaces in the atmosphere, with significant implications for the budget and distribution of atmospheric ice nucleating particles, and their consequent effects on cloud microphysics and mixed-phase clouds. The new critical surface area “g” framework that was developed by Beydoun et al. (2016), is extended to produce a heterogeneous ice nucleation mixing model that can predict the freezing behavior of multi-component particle surfaces immersed in droplets. The model successfully predicts the immersion freezing properties of droplets containing Snomax bacterial particles across a mass concentration range of seven orders of magnitude, by treating Snomax as comprised of two distinct distributions of heterogeneous ice nucleating activity. Furthermore, the model successfully predicts the immersion freezing behavior of a low concentration mixture of Snomax and illite mineral particles, a proxy for the biological-dust mixtures observed in atmospheric aerosols. It is shown that even at very low Snomax concentrations in the mixture, droplet freezing at higher temperatures is still determined solely by the second less active and more abundant distribution of heterogeneous ice nucleating activity of Snomax, while freezing at lower temperatures is determined solely by the heterogeneous ice nucleating activity of pure illite. This demonstrates that in this proxy system, biological ice nucleating particles do not compromise their ice nucleating activity upon mixing with dust and no new range of intermediary freezing temperatures associated with the mixture of ice nucleating particles of differing activities is produced. The study is the first to directly examine the freezing behavior of a mixture of Snomax and illite and presents the first multi-component ice nucleation model experimentally evaluated using a wide range of ice nucleating particle concentration mixtures in droplets.

scholarly journals Laboratory-generated mixtures of mineral dust particles with biological substances: characterization of the particle mixing state and immersion freezing behavior

2016 ◽  
Vol 16 (9) ◽  
pp. 5531-5543 ◽  
Author(s):  
Stefanie Augustin-Bauditz ◽  
Heike Wex ◽  
Cyrielle Denjean ◽  
Susan Hartmann ◽  
Johannes Schneider ◽  
...  
Keyword(s):  
Biological Material ◽  
Mineral Dust ◽  
Research Unit ◽  
Ice Nucleation ◽  
Freezing Behavior ◽  
Dust Particles ◽  
Mixing State ◽  
Nucleation Behavior ◽  
Immersion Freezing

Abstract. Biological particles such as bacteria, fungal spores or pollen are known to be efficient ice nucleating particles. Their ability to nucleate ice is due to ice nucleation active macromolecules (INMs). It has been suggested that these INMs maintain their nucleating ability even when they are separated from their original carriers. This opens the possibility of an accumulation of such INMs in soils, resulting in an internal mixture of mineral dust and INMs. If particles from such soils which contain biological INMs are then dispersed into the atmosphere due to wind erosion or agricultural processes, they could induce ice nucleation at temperatures typical for biological substances, i.e., above −20 up to almost 0 °C, while they might be characterized as mineral dust particles due to a possibly low content of biological material. We conducted a study within the research unit INUIT (Ice Nucleation research UnIT), where we investigated the ice nucleation behavior of mineral dust particles internally mixed with INM. Specifically, we mixed a pure mineral dust sample (illite-NX) with ice active biological material (birch pollen washing water) and quantified the immersion freezing behavior of the resulting particles utilizing the Leipzig Aerosol Cloud Interaction Simulator (LACIS). A very important topic concerning the investigations presented here as well as for atmospheric application is the characterization of the mixing state of aerosol particles. In the present study we used different methods like single-particle aerosol mass spectrometry, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray analysis (EDX), and a Volatility–Hygroscopicity Tandem Differential Mobility Analyser (VH-TDMA) to investigate the mixing state of our generated aerosol. Not all applied methods performed similarly well in detecting small amounts of biological material on the mineral dust particles. Measuring the hygroscopicity/volatility of the mixed particles with the VH-TDMA was the most sensitive method. We found that internally mixed particles, containing ice active biological material, follow the ice nucleation behavior observed for the pure biological particles. We verified this by modeling the freezing behavior of the mixed particles with the Soccerball model (SBM). It can be concluded that a single INM located on a mineral dust particle determines the freezing behavior of that particle with the result that freezing occurs at temperatures at which pure mineral dust particles are not yet ice active.

scholarly journals The Leipzig Cloud Interaction Simulator (LACIS): operating principle and theoretical studies concerning homogeneous and heterogeneous ice nucleation

2010 ◽  
Vol 10 (11) ◽  
pp. 25577-25617
Author(s):  
S. Hartmann ◽  
D. Niedermeier ◽  
J. Voigtländer ◽  
T. Clauss ◽  
R. A. Shaw ◽  
...  
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Nucleation Rate ◽  
Rate Coefficient ◽  
Ice Nucleation ◽  
Freezing Behavior ◽  
Nucleation Theory ◽  
Dust Particles ◽  
Immersion Freezing ◽  
Heterogeneous Ice Nucleation

Abstract. At the Leipzig Cloud Interaction Simulator (LACIS) experiments investigating homogeneous and heterogeneous nucleation of ice (particularly immersion freezing in the latter case) have been carried out. Here both the physical LACIS setup and the numerical model developed to design experiments at LACIS and interpret their results are presented in detail. Combining results from the numerical model with experimental data, it was found that for the experimental parameter space considered, classical homogeneous ice nucleation theory is able to predict the freezing behavior of highly diluted ammonium sulfate solution droplets, while classical heterogeneous ice nucleation theory, together with the assumption of a constant contact angle, fails to predict the immersion freezing behavior of surrogate mineral dust particles (Arizona Test Dust, ATD). The main reason for this failure is the compared to experimental data apparently overly strong temperature dependence of the nucleation rate coefficient. Assuming, in the numerical model, Classical Nucleation Theory (CNT) for homogeneous ice nucleation and a CNT-based parameterization for the nucleation rate coefficient in the immersion freezing mode, recently published by our group, it was found that even for a relatively effective ice nucleating agent such as pure ATD, there is a temperature range where homogeneous ice nucleation is dominant. The main explanation is the apparently different temperature dependencies of the two freezing mechanisms. Finally, reviewing the assumptions made during the derivation of the parameterization, it was found that the assumption of constant temperature during ice nucleation and the chosen nucleation time were highly justified, underlining the applicability of both the method to determine the fitting coefficients in the parameterization equation, and the validity of the parameterization concept itself.

scholarly journals The immersion freezing behavior of mineral dust particles mixed with biological substances

2015 ◽  
Vol 15 (20) ◽  
pp. 29639-29671 ◽  
Author(s):  
S. Augustin-Bauditz ◽  
H. Wex ◽  
C. Denjean ◽  
S. Hartmann ◽  
J. Schneider ◽  
...  
Keyword(s):  
Biological Material ◽  
Mineral Dust ◽  
Fungal Spores ◽  
Birch Pollen ◽  
Ice Nucleation ◽  
Freezing Behavior ◽  
Dust Particles ◽  
Nucleation Behavior ◽  
Biological Particles ◽  
Immersion Freezing

Abstract. Biological particles such as bacteria, fungal spores or pollen are known to be efficient ice nucleating particles. Their ability to nucleate ice is due to ice nucleation active macromolecules (INM). It has been suggested that these INM maintain their nucleating ability even when they are separated from their original carriers. This opens the possibility of an accumulation of such INM in e.g., soils, resulting in an internal mixture of mineral dust and INM. If particles from such soils which contain biological INM are then dispersed into the atmosphere due to wind erosion or agricultural processes, they could induce ice nucleation at temperatures typical for biological substances, i.e., above −20 up to almost 0 °C. To explore this hypothesis, we performed a measurement campaign within the research unit INUIT, where we investigated the ice nucleation behavior of mineral dust particles internally mixed with INM. Specifically, we mixed a pure mineral dust sample (illite-NX) with ice active biological material (birch pollen washing water) and quantified the immersion freezing behavior of the resulting particles utilizing the Leipzig Aerosol Cloud Interaction Simulator (LACIS). To characterize the mixing state of the generated aerosol we used different methods which will also be discussed. We found that internally mixed particles, containing ice active biological material, follow the ice nucleation behavior observed for the purely biological particles, i.e. freezing occurs at temperatures at which mineral dusts themselves are not yet ice active. It can be concluded that INM located on a mineral dust particle determine the freezing behavior of that particle.

scholarly journals Homogeneous and heterogeneous ice nucleation at LACIS: operating principle and theoretical studies

2011 ◽  
Vol 11 (4) ◽  
pp. 1753-1767 ◽  
Author(s):  
S. Hartmann ◽  
D. Niedermeier ◽  
J. Voigtländer ◽  
T. Clauss ◽  
R. A. Shaw ◽  
...  
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Nucleation Rate ◽  
Rate Coefficient ◽  
Ice Nucleation ◽  
Freezing Behavior ◽  
Nucleation Theory ◽  
Dust Particles ◽  
Immersion Freezing ◽  
Heterogeneous Ice Nucleation

Abstract. At the Leipzig Aerosol Cloud Interaction Simulator (LACIS) experiments investigating homogeneous and heterogeneous nucleation of ice (particularly immersion freezing in the latter case) have been carried out. Here both the physical LACIS setup and the numerical model developed to design experiments at LACIS and interpret their results are presented in detail. Combining results from the numerical model with experimental data, it was found that for the experimental parameter space considered, classical homogeneous ice nucleation theory is able to predict the freezing behavior of highly diluted ammonium sulfate solution droplets, while classical heterogeneous ice nucleation theory, together with the assumption of a constant contact angle, fails to predict the immersion freezing behavior of surrogate mineral dust particles (Arizona Test Dust, ATD). The main reason for this failure is the compared to experimental data apparently overly strong temperature dependence of the nucleation rate coefficient. Assuming, in the numerical model, Classical Nucleation Theory (CNT) for homogeneous ice nucleation and a CNT-based parameterization for the nucleation rate coefficient in the immersion freezing mode, recently published by our group, it was found that even for a relatively effective ice nucleating agent such as pure ATD, there is a temperature range where homogeneous ice nucleation is dominant. The main explanation is the apparently different temperature dependencies of the two freezing mechanisms. Finally, reviewing the assumptions made during the derivation of the CNT-based parameterization for immersion freezing, it was found that the assumption of constant temperature during ice nucleation and the chosen ice nucleation time were justified, underlining the applicability of the method to determine the fitting coefficients in the parameterization equation.

scholarly journals The effect of (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> on the freezing properties of non-mineral dust ice-nucleating substances of atmospheric relevance

2021 ◽  
Vol 21 (19) ◽  
pp. 14631-14648
Author(s):  
Soleil E. Worthy ◽  
Anand Kumar ◽  
Yu Xi ◽  
Jingwei Yun ◽  
Jessie Chen ◽  
...  
Keyword(s):  
Mineral Dust ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Ice Nuclei ◽  
Wide Range ◽  
Significant Difference ◽  
Mineral Dusts ◽  
Immersion Freezing ◽  
The Impact

Abstract. A wide range of materials including mineral dust, soil dust, and bioaerosols have been shown to act as ice nuclei in the atmosphere. During atmospheric transport, these materials can become coated with inorganic and organic solutes which may impact their ability to nucleate ice. While a number of studies have investigated the impact of solutes at low concentrations on ice nucleation by mineral dusts, very few studies have examined their impact on non-mineral dust ice nuclei. We studied the effect of dilute (NH4)2SO4 solutions (0.05 M) on immersion freezing of a variety of non-mineral dust ice-nucleating substances (INSs) including bacteria, fungi, sea ice diatom exudates, sea surface microlayer substances, and humic substances using the droplet-freezing technique. We also studied the effect of (NH4)2SO4 solutions (0.05 M) on the immersion freezing of several types of mineral dust particles for comparison purposes. (NH4)2SO4 had no effect on the median freezing temperature (ΔT50) of 9 of the 10 non-mineral dust materials tested. There was a small but statistically significant decrease in ΔT50 (−0.43 ± 0.19 ∘C) for the bacteria Xanthomonas campestris in the presence of (NH4)2SO4 compared to pure water. Conversely, (NH4)2SO4 increased the median freezing temperature of four different mineral dusts (potassium-rich feldspar, Arizona Test Dust, kaolinite, montmorillonite) by 3 to 9 ∘C and increased the ice nucleation active site density per gram of material (nm(T)) by a factor of ∼ 10 to ∼ 30. This significant difference in the response of mineral dust and non-mineral dust ice-nucleating substances when exposed to (NH4)2SO4 suggests that they nucleate ice and/or interact with (NH4)2SO4 via different mechanisms. This difference suggests that the relative importance of mineral dust to non-mineral dust particles for ice nucleation in mixed-phase clouds could potentially increase as these particles become coated with (NH4)2SO4 in the atmosphere. This difference also suggests that the addition of (NH4)2SO4 (0.05 M) to atmospheric samples of unknown composition could potentially be used as an indicator or assay for the presence of mineral dust ice nuclei, although additional studies are still needed as a function of INS concentration to confirm the same trends are observed for different INS concentrations than those used here. A comparison with results in the literature does suggest that our results may be applicable to a range of mineral dust and non-mineral dust INS concentrations.

scholarly journals The effect of (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> on the freezing properties of non-mineral dust ice nucleating substances of atmospheric relevance

2021 ◽  
Author(s):  
Soleil E. Worthy ◽  
Anand Kumar ◽  
Yu Xi ◽  
Jingwei Yun ◽  
Jessie Chen ◽  
...  
Keyword(s):  
Mineral Dust ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Ice Nuclei ◽  
Wide Range ◽  
Significant Difference ◽  
Mineral Dusts ◽  
Immersion Freezing ◽  
The Impact

Abstract. A wide range of materials including mineral dust, soil dust, and bioaerosols have been shown to act as ice nuclei in the atmosphere. During atmospheric transport, these materials can become coated with inorganic and organic solutes which may impact their ability to nucleate ice. While a number of studies have investigated the impact of solutes at low concentrations on ice nucleation by mineral dusts, very few studies have examined their impact on non-mineral dust ice nuclei. We studied the effect of dilute (NH4)2SO4 solutions on immersion freezing of a variety of non-mineral dust ice nucleating substances including bacteria, fungi, sea ice diatom exudates, sea surface microlayer, and humic substances using the droplet freezing technique. We also studied the effect of (NH4)2SO4 on immersion freezing of mineral dust particles for comparison purposes. (NH4)2SO4 had no effect on the median freezing temperature of nine of the ten tested non-mineral dust materials. There was a small but statistically significant decrease in the median freezing temperature of the bacteria X. campestris (change in median freezing temperature ∆T_50 = -0.43 ± 0.19 °C) in the presence of (NH4)2SO4 compared to pure water. Conversely, (NH4)2SO4 increased the median freezing temperature of four different mineral dusts (Potassium-rich feldspar, Arizona Test Dust, Kaolinite, Montmorillonite) by 3 °C to 8 °C. This significant difference in the response of mineral dust and non-mineral dust ice nucleating substances when exposed to (NH4)2SO4 suggests that they nucleate ice and/or interact with (NH4)2SO4 via different mechanisms. This difference suggests that the relative importance of mineral dust to non-mineral dust particles for ice nucleation in mixed-phase clouds could increase as these particles become coated with ammonium sulfate in the atmosphere. This difference also suggests that the addition of (NH4)2SO4 to atmospheric samples of unknown composition could be used as an indicator or assay for the presence of mineral dust ice nuclei.

scholarly journals Using critical area analysis to deconvolute internal and external particle variability in heterogeneous ice nucleation

2016 ◽  
Author(s):  
Hassan Beydoun ◽  
Ryan C. Sullivan
Keyword(s):  
Surface Area ◽  
Active Site ◽  
Internal Variability ◽  
Ice Nucleation ◽  
Critical Surface ◽  
Critical Area ◽  
Concentration Data ◽  
Immersion Freezing ◽  
Atmospherically Relevant ◽  
Heterogeneous Ice Nucleation

Abstract. Heterogeneous ice nucleation remains one of the outstanding problems in cloud physics and atmospheric science. Experimental challenges in properly simulating particle induced freezing processes under atmospherically relevant conditions have largely contributed to the absence of a consistent and comprehensive parameterization of immersion freezing properties. Here we formulate an ice active surface site based stochastic model of heterogeneous freezing with the unique feature of invoking a continuum assumption on the ice nucleating activity (contact angle) of an aerosol particle's surface, that requires no assumptions about the size or number of active sites. The result is a particle specific property g that defines a distribution of local ice nucleation rates. Upon integration this yields a full freezing probability function for an ice-nucleating particle. Current cold plate droplet freezing measurements provide a great resource for studying the freezing properties of many atmospheric aerosol systems. A method based on statistical significance to determine an ice nucleating species' specific critical surface area is presented that can resolve the two-dimensional nature of the ice nucleation ability of aerosol particles: internal variability in active site strengths and freezing rates along an individual particle's surface, as well as external variability between two particles of the same type in an aerosol population. By applying this method to experimental data we demonstrate its ability to comprehensively interpret immersion freezing temperature spectra of droplets containing variable particle concentrations. It is shown that general active site density functions such as the popular ns parameterization cannot be reliably extrapolated below this critical area threshold to describe freezing curves for lower particle surface area concentrations. Freezing curves obtained below this threshold translate to higher ns values, while the ns values are essentially the same from curves obtained above the critical area threshold. However, we can successfully predict the lower concentration freezing curves, which are more atmospherically relevant, through a process of random sampling from the statistically significant global distribution obtained from high particle concentration data. Our analysis further revealed that one individual atmospheric illite mineral particle will not contain the entire range of ice active site activity for that system (its internal variability). Comprehensive parameterizations that can predict the temporal evolution of the frozen fraction of cloud droplets in larger atmospheric models are also derived from this new framework.

scholarly journals A Study of the Role of the Parameterization of Heterogeneous Ice Nucleation for the Modeling of Microphysics and Precipitation of a Convective Cloud

2015 ◽  
Vol 72 (9) ◽  
pp. 3322-3339 ◽  
Author(s):  
T. Hiron ◽  
A. I. Flossmann
Keyword(s):  
Convective Cloud ◽  
Cloud Microphysics ◽  
Ice Nucleation ◽  
Freezing Process ◽  
Formation Mechanisms ◽  
Cloud Models ◽  
Immersion Freezing ◽  
Cloud Modeling ◽  
Heterogeneous Ice Nucleation

Abstract Even though ice formation mechanisms in clouds probably obey all the same thermodynamic principles, the associated mechanical and thermal energy transfers differ with respect to the exact pathway and the associated phases. Consequently, heterogeneous ice nucleation parameterizations play an important role in cloud modeling. The 1.5D bin-resolved microphysics Detailed Scavenging Model (DESCAM) was used to assess the role of the parameterizations for different ice initiation processes. Homogeneous nucleation, deposition freezing, contact freezing, immersion freezing, and condensation freezing were treated explicitly, and their impacts alone and in competition with each other on cloud microphysics and precipitation were studied. The role of efficiently ice-nucleating bacteria on cloud evolution was addressed, as well as means to consider different chemical natures of ice nucleation particles. For the conditions studied, it was found that deposition and contact freezing only played a negligible role with respect to the other ice-nucleating mechanisms. Homogeneous freezing and classical immersion freezing showed a similar behavior. Both freezing rates increase with increasing drop age (i.e., size). This suggests a possibility for regrouping processes in future parameterized cloud models. Condensation freezing parameterization, however, acts at much warmer temperatures in clouds and for much smaller drops. The associated release of latent heat at lower altitudes caused significantly different cloud dynamics with respect to homogeneous/immersion freezing. This suggests that, in future parameterized models, the condensation freezing process needs particular attention, as well as the fact that ice-forming nuclei (IN) are a subset of aerosol particles that are depleted and replenished like the rest of the population.

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