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.

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 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 Analysis of isothermal and cooling rate dependent immersion freezing by a unifying stochastic ice nucleation model

2015 ◽  
Vol 15 (9) ◽  
pp. 13109-13166
Author(s):  
P. A. Alpert ◽  
D. A. Knopf
Keyword(s):  
Cooling Rate ◽  
Surface Area ◽  
Ice Nucleation ◽  
Rate Dependence ◽  
Nucleation Theory ◽  
Freezing Process ◽  
Nucleation Kinetics ◽  
Rate Dependent ◽  
Immersion Freezing ◽  
The Impact

Abstract. Immersion freezing is an important ice nucleation pathway involved in the formation of cirrus and mixed-phase clouds. Laboratory immersion freezing experiments are necessary to determine the range in temperature (T) and relative humidity (RH) at which ice nucleation occurs and to quantify the associated nucleation kinetics. Typically, isothermal (applying a constant temperature) and cooling rate dependent immersion freezing experiments are conducted. In these experiments it is usually assumed that the droplets containing ice nuclei (IN) all have the same IN surface area (ISA), however the validity of this assumption or the impact it may have on analysis and interpretation of the experimental data is rarely questioned. A stochastic immersion freezing model based on first principles of statistics is presented, which accounts for variable ISA per droplet and uses physically observable parameters including the total number of droplets (Ntot) and the heterogeneous ice nucleation rate coefficient, Jhet(T). This model is applied to address if (i) a time and ISA dependent stochastic immersion freezing process can explain laboratory immersion freezing data for different experimental methods and (ii) the assumption that all droplets contain identical ISA is a valid conjecture with subsequent consequences for analysis and interpretation of immersion freezing. The simple stochastic model can reproduce the observed time and surface area dependence in immersion freezing experiments for a variety of methods such as: droplets on a cold-stage exposed to air or surrounded by an oil matrix, wind and acoustically levitated droplets, droplets in a continuous flow diffusion chamber (CFDC), the Leipzig aerosol cloud interaction simulator (LACIS), and the aerosol interaction and dynamics in the atmosphere (AIDA) cloud chamber. Observed time dependent isothermal frozen fractions exhibiting non-exponential behavior with time can be readily explained by this model considering varying ISA. An apparent cooling rate dependence ofJhet is explained by assuming identical ISA in each droplet. When accounting for ISA variability, the cooling rate dependence of ice nucleation kinetics vanishes as expected from classical nucleation theory. The model simulations allow for a quantitative experimental uncertainty analysis for parameters Ntot, T, RH, and the ISA variability. In an idealized cloud parcel model applying variability in ISAs for each droplet, the model predicts enhanced immersion freezing temperatures and greater ice crystal production compared to a case when ISAs are uniform in each droplet. The implications of our results for experimental analysis and interpretation of the immersion freezing process are discussed.

scholarly journals A New Ice Nucleation Active Site Parameterization for Desert Dust and Soot

2017 ◽  
Vol 74 (3) ◽  
pp. 699-717 ◽  
Author(s):  
Romy Ullrich ◽  
Corinna Hoose ◽  
Ottmar Möhler ◽  
Monika Niemand ◽  
Robert Wagner ◽  
...  
Keyword(s):  
Active Surface ◽  
Ice Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Negative Slope ◽  
Organic Carbon Content ◽  
Desert Dust ◽  
Soot Aerosol ◽  
Immersion Freezing ◽  
Heterogeneous Ice Nucleation

Abstract Based on results of 11 yr of heterogeneous ice nucleation experiments at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) chamber in Karlsruhe, Germany, a new empirical parameterization framework for heterogeneous ice nucleation was developed. The framework currently includes desert dust and soot aerosol and quantifies the ice nucleation efficiency in terms of the ice nucleation active surface site (INAS) approach. The immersion freezing INAS densities nS of all desert dust experiments follow an exponential fit as a function of temperature, well in agreement with an earlier analysis of AIDA experiments. The deposition nucleation nS isolines for desert dust follow u-shaped curves in the ice saturation ratio–temperature (Si–T) diagram at temperatures below about 240 K. The negative slope of these isolines toward lower temperatures may be explained by classical nucleation theory (CNT), whereas the behavior toward higher temperatures may be caused by a pore condensation and freezing mechanism. The deposition nucleation measured for soot at temperatures below about 240 K also follows u-shaped isolines with a shift toward higher Si for soot with higher organic carbon content. For immersion freezing of soot aerosol, only upper limits for nS were determined and used to rescale an existing parameterization line. The new parameterization framework is compared to a CNT-based parameterization and an empirical framework as used in models. The comparison shows large differences in shape and magnitude of the nS isolines especially for deposition nucleation. For the application in models, implementation of this new framework is simple compared to that of other expressions.

scholarly journals Comparing contact and immersion freezing from continuous flow diffusion chambers

2016 ◽  
Author(s):  
Baban Nagare ◽  
Claudia Marcolli ◽  
André Welti ◽  
Olaf Stetzer ◽  
Ulrike Lohmann
Keyword(s):  
Residence Time ◽  
Continuous Flow ◽  
Diffusion Chamber ◽  
Ice Nucleation ◽  
Freezing Process ◽  
Electrical Mobility ◽  
Cloud Droplets ◽  
Immersion Freezing ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

Abstract. Ice nucleating particles (INPs) in the atmosphere are responsible for glaciating cloud droplets between 237 K and 273 K. Different mechanisms of heterogeneous ice nucleation can compete under mixed-phase cloud conditions. Contact freezing is considered relevant because higher ice nucleation temperatures than for immersion freezing for the same INPs were observed. It has limitations because its efficiency depends on the number of collisions between cloud droplets and INPs. This study compares immersion and contact freezing efficiencies of three different INPs. The contact freezing data was obtained with the ETH CoLlision Ice Nucleation CHamber (CLINCH) using 80 μm diameter droplets which can interact with INPs for residence times of 2 s and 4 s in the chamber. The contact freezing efficiency was calculated by estimating the number of collisions between droplets and particles. Theoretical formulations of collision efficiencies gave too high freezing efficiencies for all investigated INPs, namely AgI particles with 200 nm electrical mobility diameter, 400 and 800 nm diameter ATD and kaolinite particles. Comparison of freezing efficiencies by contact and immersion freezing is therefore limited by the accuracy of collision efficiencies. The concentration of particles was 1000 cm−3 for ATD and kaolinite and 500, 1000, 2000 and 5000 cm−3 for AgI. For concentrations < 5000 cm−3, the droplets collect only one particle on average during their time in the chamber. For ATD and kaolinite particles, contact freezing efficiencies at 2 s residence time were smaller than at 4 s, which is in disagreement with a collisional contact freezing process but in accordance with contact freezing insideout or immersion freezing. For best comparison with contact freezing results, immersion freezing experiments of the same INPs were performed with the continuous flow diffusion chamber IMCA/ZINC for 3 s residence time. In IMCA/ZINC, each INP is activated into a droplet in IMCA and provides its surface for ice nucleation in the ZINC chamber. The comparison of contact and immersion freezing results did not confirm a general enhancement of freezing efficiency for contact compared with immersion freezing experiments. For AgI particles the onset of heterogeneous freezing in CLINCH was even shifted to lower temperatures compared with IMCA/ZINC. For ATD, freezing efficiencies for contact and immersion freezing experiments were similar. For kaolinite particles, contact freezing became detectable at higher temperatures than immersion freezing. Using contact angle information between water and the INP, it is discussed how the position of the INP in or on the droplets may influence its ice nucleation activity.

scholarly journals BINARY: an optical freezing array for assessing temperature and time dependence of heterogeneous ice nucleation

2015 ◽  
Vol 8 (2) ◽  
pp. 689-703 ◽  
Author(s):  
C. Budke ◽  
T. Koop
Keyword(s):  
Time Dependence ◽  
Ice Nucleation ◽  
Small Time ◽  
Cooling Rates ◽  
Vapor Transfer ◽  
Ice Nucleators ◽  
Immersion Freezing ◽  
Type Water ◽  
Optical Brightness ◽  
Heterogeneous Ice Nucleation

Abstract. A new optical freezing array for the study of heterogeneous ice nucleation in microliter-sized droplets is introduced, tested and applied to the study of immersion freezing in aqueous Snomax® suspensions. In the Bielefeld Ice Nucleation ARraY (BINARY) ice nucleation can be studied simultaneously in 36 droplets at temperatures down to −40 °C (233 K) and at cooling rates between 0.1 and 10 K min−1. The droplets are separated from each other in individual compartments, thus preventing a Wegener–Bergeron–Findeisen type water vapor transfer between droplets as well as avoiding the seeding of neighboring droplets by formation and surface growth of frost halos. Analysis of freezing and melting occurs via an automated real-time image analysis of the optical brightness of each individual droplet. As an application ice nucleation in water droplets containing Snomax® at concentrations from 1 ng mL−1 to 1 mg mL−1 was investigated. Using different cooling rates, a small time dependence of ice nucleation induced by two different classes of ice nucleators (INs) contained in Snomax® was detected and the corresponding heterogeneous ice nucleation rate coefficient was quantified. The observed time dependence is smaller than those of other types of INs reported in the literature, suggesting that the BINARY setup is suitable for quantifying time dependence for most other INs of atmospheric interest, making it a useful tool for future investigations.

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 Interpretation of freezing nucleation experiments: singular and stochastic; sites and surfaces

2014 ◽  
Vol 14 (2) ◽  
pp. 1711-1760
Author(s):  
G. Vali
Keyword(s):  
Specific Surface ◽  
Laboratory Experiments ◽  
Solid Phase ◽  
Ice Nucleation ◽  
Detailed Knowledge ◽  
Primary Role ◽  
Surface Sites ◽  
Immersion Freezing ◽  
Major Factors

Abstract. Publications of recent years dealing with laboratory experiments of immersion freezing reveal uncertainties about the fundamentals of heterogeneous freezing nucleation. While it appears well accepted that there are two major factors that determine the process, namely fluctuations in the size and configuration of incipient embryos of the solid phase and the role of the substrate to aid embryo formation, views have been evolving about the relative importance of these two elements. The importance of specific surface sites is being established in a growing number of experiments and a number of approaches have been proposed to incorporate these results into model descriptions. Many of these models share a common conceptual basis yet diverge in the way random and deterministic factors are combined. The divergence can be traced to uncertainty about the permanence of nucleating sites, to the lack of detailed knowledge about what surface features constitute nucleating sites, and to the consequent need to rely on empirical or parametric formulas to define the population of sites of different effectiveness. The goal of this paper is to demonstrate that recent experiments and models, consistent with earlier work, point to the existence and primary role of permanent nucleating sites and to the continued need for empirically based formulations of heterogeneous freezing. The paper focuses on three identifiably separate but interrelated issues: (i) the combination of singular and stochastic factors, (ii) the role of specific surface sites, and (iii) the modeling of heterogeneous ice nucleation.

scholarly journals Immersion freezing of ice nucleating active protein complexes

2012 ◽  
Vol 12 (8) ◽  
pp. 21321-21353 ◽  
Author(s):  
S. Hartmann ◽  
S. Augustin ◽  
T. Clauss ◽  
J. Voigtländer ◽  
D. Niedermeier ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Nucleation Rate ◽  
Protein Complex ◽  
Protein Complexes ◽  
Ice Nucleation ◽  
Temperature Range ◽  
Immersion Freezing ◽  
New Perspective ◽  
Lower Temperature ◽  
Heterogeneous Ice Nucleation

Abstract. Biological particles, e.g. bacteria and their Ice Nucleating Active (INA) protein complexes, might play an important role for the ice formation in atmospheric mixed-phase clouds. Therefore, the immersion freezing behavior of INA protein complexes generated from a SnomaxTM solution/suspension was investigated as function of temperature in a range of −5 °C to −38 °C at the Leipzig Aerosol Cloud Interaction Simulator (LACIS). The immersion freezing of droplets containing small numbers of INA protein complexes occurs in a temperature range of −7 °C and −10 °C. The experiments performed in the lower temperature range, where all droplets freeze which contain at least one INA protein complex, are used to determine the average number of INA protein complexes present, assuming that the INA protein complexes are Poisson distributed over the droplet ensemble. Knowing the average number of INA protein complexes, the heterogeneous ice nucleation rate and rate coefficient of a single INA protein complex is determined by using the newly-developed CHESS model (stoCHastic model of idEntical poiSSon distributed ice nuclei). Therefore, we assume the ice nucleation process to be of stochastic nature, and a parameterization of the INA protein complex's nucleation rate. Analyzing the results of immersion freezing experiments from literature (SnomaxTM and Pseudomonas syringae bacteria), to results gained in this study, demonstrates that first, a similar temperature dependence of the heterogeneous ice nucleation rate for a single INA protein complex was found in all experiments, second, the shift of the ice fraction curves to higher temperatures can be explained consistently by a higher average number of INA protein complexes being present in the droplet ensemble, and finally the heterogeneous ice nucleation rate of one single INA protein complex might be also applicable for intact Pseudomonas syringae bacteria cells. The results obtained in this study allow a new perspective on the interpretation of immersion freezing experiments considering INA protein complexes and the derived simple parameterization of the heterogeneous ice nucleation rate can be used in cloud resolving models for studying the effect of bacteria induced ice nucleation.

scholarly journals Development, Characterization, and Validation of a Cold Stage-Based Ice Nucleation Array (PKU-INA)

Atmosphere ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 357 ◽  
Author(s):  
Jie Chen ◽  
Xiangyu Pei ◽  
Hong Wang ◽  
Jingchuan Chen ◽  
Yishu Zhu ◽  
...  
Keyword(s):  
Ice Nucleation ◽  
Temperature Calibration ◽  
Cold Stage ◽  
Reliable Instrument ◽  
Peking University ◽  
Calibration Protocol ◽  
Immersion Freezing ◽  
And Performance ◽  
Good Agreement ◽  
Heterogeneous Ice Nucleation

A drop-freeze array (PeKing University Ice Nucleation Array, PKU-INA) was developed based on the cold-stage method to investigate heterogeneous ice nucleation properties of atmospheric particles in the immersion freezing mode from −30 to 0 °C. The instrumental details as well as characterization and performance evaluation are described in this paper. A careful temperature calibration protocol was developed in our work. The uncertainties in the reported temperatures were found to be less than 0.4 °C at various cooling rates after calibration. We also measured the ice nucleation activities of droplets containing different mass concentrations of illite NX, and the results obtained in our work show good agreement with those reported previously using other instruments with similar principles. Overall, we show that our newly developed PKU-INA is a robust and reliable instrument for investigation of heterogeneous ice nucleation in the immersion freezing mode.

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