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

Hartmann, S.; Niedermeier, D.; Voigtländer, Jens; Clauß, T.; Shaw, Raymond A.; Wex, Heike; Kiselev, Alexei; Stratmann, Frank

doi:10.5194/acp-11-1753-2011

Cited by 70 publications

(112 citation statements)

References 51 publications

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“…The ATD particles facilitate the ice nucleation at warmer temperatures, in agreement with similar studies (Niedermeier et al, 2010;Hartmann et al, 2011), and the freezing depression follows the water-activity-based ice nucleation curves. Here, the dependence of the freezing point on the droplet volume is more pronounced, as the surface area of the immersed particles is higher; hence, they contain higher number of nucleation sites (Marcolli et al, 2007) as will be shown in the next section for two more types of dust.…”

Section: Homogeneous and Heterogeneous Freezing Of Aqueous Solutionssupporting

confidence: 76%

The WeIzmann Supercooled Droplets Observation on a Microarray (WISDOM) and application for ambient dust

2018

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Abstract. The WeIzmann Supercooled Droplets Observation on Microarray (WISDOM) is a new setup for studying ice nucleation in an array of monodisperse droplets for atmospheric implications. WISDOM combines microfluidics techniques for droplets production and a cryo-optic stage for observation and characterization of freezing events of individual droplets. This setup is designed to explore heterogeneous ice nucleation in the immersion freezing mode, down to the homogeneous freezing of water (235 K) in various cooling rates (typically 0.1-10 K min −1 ). It can also be used for studying homogeneous freezing of aqueous solutions in colder temperatures. Frozen fraction, ice nucleation active surface site densities and freezing kinetics can be obtained from WISDOM measurements for hundreds of individual droplets in a single freezing experiment. Calibration experiments using eutectic solutions and previously studied materials are described. WISDOM also allows repeatable cycles of cooling and heating for the same array of droplets. This paper describes the WISDOM setup, its temperature calibration, validation experiments and measurement uncertainties. Finally, application of WISDOM to study the ice nucleating particle (INP) properties of size-selected ambient Saharan dust particles is presented.

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Section: Homogeneous and Heterogeneous Freezing Of Aqueous Solutionssupporting

confidence: 76%

The WeIzmann Supercooled Droplets Observation on a Microarray (WISDOM) and application for ambient dust

2018

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“…This is an innovation compared to older studies (Niedermeier et al, 2010(Niedermeier et al, , 2011bHartmann et al, 2011) in which only the temperature range between −26 • C and −40 • C was covered. Furthermore, taking advantage of TOPS-Ice's ability to distinguish the phase states of the hydrometeors leaving LACIS, and in contrast to former investigations, LACIS was run such that both droplets and ice particles were present at its outlet.…”

Section: Lacismentioning

confidence: 99%

“…In the framework of the present paper, it is used for investigating the immersion freezing behaviour of well-characterised, size-selected particles generated from a Snomax TM solution/suspension as a function of temperature with only one particle immersed in each droplet. In this section, the setup and operating principle will be described briefly, especially with respect to technical innovations, compared to former experiments as described in Niedermeier et al (2010Niedermeier et al ( , 2011b and Hartmann et al (2011).…”

Section: Lacismentioning

confidence: 99%

“…In addition to the measurements performed in the temperature range between 0 • C to −25 • C, experiments were also carried out at lower temperatures (ranging from −26 • C to −38 • C), following the operation mode described in Hartmann et al (2011), however, with higher inlet dew point temperatures to ensure that both droplets and ice particles pass through the outlet of LACIS. …”

Section: Lacismentioning

confidence: 99%

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Immersion freezing of ice nucleation active protein complexes

et al. 2013

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Utilising the Leipzig Aerosol Cloud Interaction Simulator (LACIS), the immersion freezing behaviour of droplet ensembles containing monodisperse particles, generated from a Snomax™ solution/suspension, was investigated. Thereto ice fractions were measured in the temperature range between −5 °C to −38 °C. Snomax™ is an industrial product applied for artificial snow production and contains Pseudomonas syringae} bacteria which have long been used as model organism for atmospheric relevant ice nucleation active (INA) bacteria. The ice nucleation activity of such bacteria is controlled by INA protein complexes in their outer membrane.

In our experiments, ice fractions increased steeply in the temperature range from about −6 °C to about −10 °C and then levelled off at ice fractions smaller than one. The plateau implies that not all examined droplets contained an INA protein complex. Assuming the INA protein complexes to be Poisson distributed over the investigated droplet populations, we developed the CHESS model (stoCHastic modEl of similar and poiSSon distributed ice nuclei) which allows for the calculation of ice fractions as function of temperature and time for a given nucleation rate. Matching calculated and measured ice fractions, we determined and parameterised the nucleation rate of INA protein complexes exhibiting class III ice nucleation behaviour. Utilising the CHESS model, together with the determined nucleation rate, we compared predictions from the model to experimental data from the literature and found good agreement.

We found that (a) the heterogeneous ice nucleation rate expression quantifying the ice nucleation behaviour of the INA protein complex is capable of describing the ice nucleation behaviour observed in various experiments for both, Snomax™ and P. syringae bacteria, (b) the ice nucleation rate, and its temperature dependence, seem to be very similar regardless of whether the INA protein complexes inducing ice nucleation are attached to the outer membrane of intact bacteria or membrane fragments, (c) the temperature range in which heterogeneous droplet freezing occurs, and the fraction of droplets being able to freeze, both depend on the actual number of INA protein complexes present in the droplet ensemble, and (d) possible artifacts suspected to occur in connection with the drop freezing method, i.e., the method frequently used by biologist for quantifying ice nucleation behaviour, are of minor importance, at least for substances such as P. syringae, which induce freezing at comparably high temperatures. The last statement implies that for single ice nucleation entities such as INA protein complexes, it is the number of entities present in the droplet population, and the entities' nucleation rate, which control the freezing behaviour of the droplet population. Quantities such as ice active surface site density are not suitable in this context.

The results obtained in this study allow a different perspective on the quantification of the immersi...

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“…This leads to an upper limit on INP concentrations that are observable with this methodology (DeMott et al, 2011). A flow tube (e.g., Leipzig Aerosol Cloud Interaction Simulator or LACIS, Hartmann et al, 2011) has also been developed in which a humidified stream containing aerosol particles is first cooled to activate droplets on the particles, which upon further cooling may then freeze.…”

Section: State Of the Art Of In Measurement Techniquesmentioning

confidence: 99%

A comprehensive laboratory study on the immersion freezing behavior of illite NX particles: a comparison of 17 ice nucleation measurement techniques

et al. 2015

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Abstract. Immersion freezing is the most relevant heterogeneous ice nucleation mechanism through which ice crystals are formed in mixed-phase clouds. In recent years, an increasing number of laboratory experiments utilizing a variety of instruments have examined immersion freezing activity of atmospherically relevant ice-nucleating particles. However, an intercomparison of these laboratory results is a difficult task because investigators have used different ice nucleation (IN) measurement methods to produce these results. A remaining challenge is to explore the sensitivity and accuracy of these techniques and to understand how the IN results are potentially influenced or biased by experimental parameters associated with these techniques.Within the framework of INUIT (Ice Nuclei Research Unit), we distributed an illite-rich sample (illite NX) as a representative surrogate for atmospheric mineral dust particles to investigators to perform immersion freezing experiments using different IN measurement methods and to obtain Published by Copernicus Publications on behalf of the European Geosciences Union. N. Hiranuma et al.: A comparison of 17 IN measurement techniquesIN data as a function of particle concentration, temperature (T ), cooling rate and nucleation time. A total of 17 measurement methods were involved in the data intercomparison. Experiments with seven instruments started with the test sample pre-suspended in water before cooling, while 10 other instruments employed water vapor condensation onto drydispersed particles followed by immersion freezing. The resulting comprehensive immersion freezing data set was evaluated using the ice nucleation active surface-site density, n s , to develop a representative n s (T ) spectrum that spans a wide temperature range (−37 • C < T < −11 • C) and covers 9 orders of magnitude in n s .In general, the 17 immersion freezing measurement techniques deviate, within a range of about 8 • C in terms of temperature, by 3 orders of magnitude with respect to n s . In addition, we show evidence that the immersion freezing efficiency expressed in n s of illite NX particles is relatively independent of droplet size, particle mass in suspension, particle size and cooling rate during freezing. A strong temperature dependence and weak time and size dependence of the immersion freezing efficiency of illite-rich clay mineral particles enabled the n s parameterization solely as a function of temperature. We also characterized the n s (T ) spectra and identified a section with a steep slope between −20 and −27 • C, where a large fraction of active sites of our test dust may trigger immersion freezing. This slope was followed by a region with a gentler slope at temperatures below −27 • C. While the agreement between different instruments was reasonable below ∼ −27 • C, there seemed to be a different trend in the temperature-dependent ice nucleation activity from the suspension and dry-dispersed particle measurements for this mineral dust, in particular at higher temperatures. For instance,...

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

Cited by 70 publications

References 51 publications

The WeIzmann Supercooled Droplets Observation on a Microarray (WISDOM) and application for ambient dust

The WeIzmann Supercooled Droplets Observation on a Microarray (WISDOM) and application for ambient dust

Immersion freezing of ice nucleation active protein complexes

A comprehensive laboratory study on the immersion freezing behavior of illite NX particles: a comparison of 17 ice nucleation measurement techniques

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