Characterization of individual ice residual particles by the single droplet freezing method: a case study in the Asian dust outflow region

Abstract. In order to better characterize ice nucleating (IN) aerosol particles in the atmosphere, we investigated the chemical composition, mixing state, and morphology of atmospheric aerosols that nucleate ice under conditions relevant for mixed-phase clouds. Five standard mineral dust samples (quartz, K-feldspar, Na-feldspar, Arizona test dust, and Asian dust source particles) were compared with actual aerosol particles collected from the west coast of Japan (the city of Kanazawa) during Asian dust events in February and April 2016. Following droplet activation by particles deposited on a hydrophobic Si (silicon) wafer substrate under supersaturated air, individual IN particles were located using an optical microscope by gradually cooling the temperature to −30 ∘C. For the aerosol samples, both the IN active particles and non-active particles were analyzed individually by atomic force microscopy (AFM), micro-Raman spectroscopy, and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). Heterogeneous ice nucleation in all standard mineral dust samples tested in this study was observed at consistently higher temperatures (e.g., −22.2 to −24.2 ∘C with K-feldspar) than the homogeneous freezing temperature (−36.5 ∘C). Meanwhile, most of the IN active atmospheric particles formed ice below −28 ∘C, i.e., at lower temperatures than the standard mineral dust samples of pure components. The most abundant IN active particles above −30 ∘C were predominantly irregular solid particles that showed clay mineral characteristics (or mixtures of several mineral components). Other than clay, Ca-rich particles internally mixed with other components, such as sulfate, were also regarded as IN active particle types. Moreover, sea salt particles were predominantly found in the non-active fraction, and internal mixing with sea salt clearly acted as a significant inhibiting agent for the ice nucleation activity of mineral dust particles. Also, relatively pure or fresh calcite, Ca(NO3)2, and (NH4)2SO4 particles were more often found in the non-active fraction. In this study, we demonstrated the capability of the combined single droplet freezing method and thorough individual particle analysis to characterize the ice nucleation activity of atmospheric aerosols. We also found that dramatic changes in the particle mixing states during long-range transport had a complex effect on the ice nucleation activity of the host aerosol particles. A case study in the Asian dust outflow region highlighted the need to consider particle mixing states, which can dramatically influence ice nucleation activity.

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Characterization of individual ice nuclei by the single droplet freezing method: a case study in the Asian dust outflow region

10.5194/acp-2017-301 ◽

2017 ◽

Author(s):

Ayumi Iwata ◽

Atsushi Matsuki

Keyword(s):

Atmospheric Aerosols ◽

Mineral Dust ◽

Aerosol Particles ◽

Ice Nucleation ◽

Asian Dust ◽

Particle Mixing ◽

Active Particles ◽

Nucleation Activity ◽

Mixing States ◽

Ice Nucleation Activity

Abstract. In order to better characterize ice-nucleating (IN) aerosol particles in the atmosphere, we investigated the chemical composition, mixing state, and morphology of atmospheric aerosols that nucleate ice under conditions relevant for mixed phase clouds. Five standard mineral dust samples (quartz, K-feldspar, Na-feldspar, Arizona test dust, and Asian dust source particles) were compared with actual aerosol particles collected from the west coast of Japan (Kanazawa City) during Asian dust events in February and April 2016. Following droplet activation by particles deposited 5 on a hydrophobic Si wafer substrate under supersaturated air, individual IN particles were located using an optical microscope by gradually cooling the temperature to −30 °C. For the aerosol samples, both the IN active particles and non-active particles were analyzed individually by Atomic Force Microscopy (AFM), micro-Raman spectroscopy, and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray spectroscopy (EDX). Heterogeneous ice nucleation in all standard mineral dust samples tested in this study was observed at consistently higher temperatures (−25.7 °C) than the homogeneous freezing temperature (−36.5 °C). Meanwhile, most of the IN active atmospheric particles formed ice below −28 °C and were found to be IN active, but slower than the standard mineral dust samples of pure components. The most abundant IN active particles above −30 °C were predominantly irregular solid particles that showed clay mineral characteristics (or mixtures of several mineral components). Other than clay, Ca-rich particles internally mixed with other components, such as sulfate, were also regarded as IN active particle types. Moreover, sea salt particles were predominantly found in the non-active fraction, and internal mixing with sea salt clearly acted as a significant inhibiting agent for the ice nucleation activity of mineral dust particles. Also, relatively pure or fresh calcite, Ca(NO3)2, and (NH4)2SO4 particles were more often found in the non-active fraction. In this study, we demonstrated the capability of the combined single droplet freezing method and thorough individual particle analysis to characterize the ice nucleation activity of atmospheric aerosols. We also found that dramatic changes in the particle mixing states during long-range transport had a complex effect on the ice nucleation activity of the host aerosol particles. A case study in the Asian dust outflow region highlighted the need to consider particle mixing states, which can dramatically influence ice nucleation activity.

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Enhanced ice nucleation activity of coal fly ash aerosol particles initiated by ice-filled pores

10.5194/acp-2019-7 ◽

2019 ◽

Author(s):

Nsikanabasi Silas Umo ◽

Robert Wagner ◽

Romy Ullrich ◽

Alexei Kiselev ◽

Harald Saathoff ◽

...

Keyword(s):

Fly Ash ◽

Significant Role ◽

Coal Fly Ash ◽

Aerosol Particles ◽

Ice Nucleation ◽

Temperature Cycling ◽

Cloud Formation ◽

Ice Formation ◽

Nucleation Activity ◽

Ice Nucleation Activity

Abstract. Ice-nucleating particles (INPs), which are precursors for ice formation in clouds, can alter the microphysical and optical properties of clouds, hence, impacting the cloud lifetimes and hydrological cycles. However, the mechanisms with which these INPs nucleate ice when exposed to different atmospheric conditions are still unclear for some particles. Recently, some INPs with pores or permanent surface defects of regular or irregular geometries have been reported to initiate ice formation at cirrus temperatures via the liquid phase in a two-step process, involving the condensation and freezing of supercooled water inside these pores. This mechanism has therefore been labelled as pore condensation and freezing (PCF). The PCF mechanism allows formation and stabilization of ice germs in the particle without the formation of macroscopic ice. Coal fly ash (CFA) aerosol particles are known to nucleate ice in the immersion freezing mode and may play a significant role in cloud formation. In our current ice nucleation experiments with CFA particles, which we conducted in the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) aerosol and cloud simulation chamber at the Karlsruhe Institute of Technology, Germany, we partly observed a strong increase in the ice-active fraction for experiments performed at temperatures just below the homogeneous freezing of pure water, which could be related to the PCF mechanism. To further investigate the potential of CFA particles undergoing PCF mechanism, we performed a series of temperature-cycling experiments in AIDA. The temperature-cycling experiments involve exposing CFA particles to lower temperatures (down to ~ 228 K), then warming them up to higher temperatures (238 K–273 K) before investigating their ice nucleation properties. For the first time, we report the enhancement of the ice nucleation activity of the CFA particles for temperatures up to 263 K, from which we conclude that it is most likely due to the PCF mechanism. This indicates that ice germs formed in the CFA particles’ pores during cooling remains in the pores during the warming and induces ice crystallization as soon as the pre-activated particles experience ice-supersaturated conditions at warmer temperatures; hence, showing an enhancement in their ice-nucleating ability compared to the scenario where the CFA particles are directly probed at warmer temperatures without temporary cooling. The enhancement in the ice nucleation ability showed a positive correlation with the specific surface area and porosity of the particles. On the one hand, the PCF mechanism could be the prevalent nucleation mode for intrinsic ice formation at cirrus temperatures rather than the previously acclaimed deposition mode. On the other, the PCF mechanism can also play a significant role in mixed-phase cloud formation in a case where the CFA particles are injected from higher altitudes and then transported to lower altitudes after being exposed to lower temperatures.

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Deposition and immersion-mode nucleation of ice by three distinct samples of volcanic ash

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-7523-2015 ◽

2015 ◽

Vol 15 (13) ◽

pp. 7523-7536 ◽

Cited By ~ 16

Author(s):

G. P. Schill ◽

K. Genareau ◽

M. A. Tolbert

Keyword(s):

Volcanic Ash ◽

Mineral Dust ◽

Global Climate ◽

Volcanic Eruptions ◽

Silica Content ◽

Ice Nucleation ◽

Ice Nuclei ◽

Immersion Freezing ◽

Nucleation Activity ◽

Ice Nucleation Activity

Abstract. Ice nucleation of volcanic ash controls both ash aggregation and cloud glaciation, which affect atmospheric transport and global climate. Previously, it has been suggested that there is one characteristic ice nucleation efficiency for all volcanic ash, regardless of its composition, when accounting for surface area; however, this claim is derived from data from only two volcanic eruptions. In this work, we have studied the depositional and immersion freezing efficiency of three distinct samples of volcanic ash using Raman microscopy coupled to an environmental cell. Ash from the Fuego (basaltic ash, Guatemala), Soufrière Hills (andesitic ash, Montserrat), and Taupo (Oruanui eruption, rhyolitic ash, New Zealand) volcanoes were chosen to represent different geographical locations and silica content. All ash samples were quantitatively analyzed for both percent crystallinity and mineralogy using X-ray diffraction. In the present study, we find that all three samples of volcanic ash are excellent depositional ice nuclei, nucleating ice from 225 to 235 K at ice saturation ratios of 1.05 ± 0.01, comparable to the mineral dust proxy kaolinite. Since depositional ice nucleation will be more important at colder temperatures, fine volcanic ash may represent a global source of cold-cloud ice nuclei. For immersion freezing relevant to mixed-phase clouds, however, only the Oruanui ash exhibited appreciable heterogeneous ice nucleation activity. Similar to recent studies on mineral dust, we suggest that the mineralogy of volcanic ash may dictate its ice nucleation activity in the immersion mode.

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Freezing of water droplets seeded with atmospheric aerosols and ice nucleation activity of the aerosols

Journal of Aerosol Science ◽

10.1016/0021-8502(94)90053-1 ◽

1994 ◽

Vol 25 (5) ◽

pp. 867-877 ◽

Cited By ~ 13

Author(s):

V. Stoyanova ◽

D. Kashchiev ◽

T. Kupenova

Keyword(s):

Atmospheric Aerosols ◽

Ice Nucleation ◽

Water Droplets ◽

Nucleation Activity ◽

Ice Nucleation Activity

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-2489-2015 ◽

2015 ◽

Vol 15 (5) ◽

pp. 2489-2518 ◽

Cited By ~ 123

Author(s):

N. Hiranuma ◽

S. Augustin-Bauditz ◽

H. Bingemer ◽

C. Budke ◽

J. Curtius ◽

...

Keyword(s):

Cooling Rate ◽

Surface Area ◽

Mineral Dust ◽

Measurement Techniques ◽

Ice Nucleation ◽

Measurement Methods ◽

Dust Particles ◽

Immersion Freezing ◽

Nucleation Activity ◽

Ice Nucleation Activity

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 IN 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 dry-dispersed particles followed by immersion freezing. The resulting comprehensive immersion freezing data set was evaluated using the ice nucleation active surface-site density, ns, to develop a representative ns(T) spectrum that spans a wide temperature range (−37 °C < T < −11 °C) and covers 9 orders of magnitude in ns. 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 ns. In addition, we show evidence that the immersion freezing efficiency expressed in ns 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 ns parameterization solely as a function of temperature. We also characterized the ns(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, the ice nucleation activity expressed in ns was smaller for the average of the wet suspended samples and higher for the average of the dry-dispersed aerosol samples between about −27 and −18 °C. Only instruments making measurements with wet suspended samples were able to measure ice nucleation above −18 °C. A possible explanation for the deviation between −27 and −18 °C is discussed. Multiple exponential distribution fits in both linear and log space for both specific surface area-based ns(T) and geometric surface area-based ns(T) are provided. These new fits, constrained by using identical reference samples, will help to compare IN measurement methods that are not included in the present study and IN data from future IN instruments.

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Deposition and immersion mode nucleation of ice by three distinct samples of volcanic ash using Raman spectroscopy

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-1385-2015 ◽

2015 ◽

Vol 15 (2) ◽

pp. 1385-1420 ◽

Cited By ~ 2

Author(s):

G. P. Schill ◽

K. Genareau ◽

M. A. Tolbert

Keyword(s):

Volcanic Ash ◽

Mineral Dust ◽

Global Climate ◽

Volcanic Eruptions ◽

Silica Content ◽

Ice Nucleation ◽

Ice Nuclei ◽

Immersion Freezing ◽

Nucleation Activity ◽

Ice Nucleation Activity

Abstract. Ice nucleation on volcanic ash controls both ash aggregation and cloud glaciation, which affect atmospheric transport and global climate. Previously, it has been suggested that there is one characteristic ice nucleation efficiency for all volcanic ash, regardless of its composition, when accounting for surface area; however, this claim is derived from data from only two volcanic eruptions. In this work, we have studied the depositional and immersion freezing efficiency of three distinct samples of volcanic ash using Raman Microscopy coupled to an environmental cell. Ash from the Fuego (basaltic ash, Guatemala), Soufrière Hills (andesitic ash, Montserrat), and Taupo (Oruanui euption, rhyolitic ash, New Zealand) volcanoes were chosen to represent different geographical locations and silica content. All ash samples were quantitatively analyzed for both percent crystallinity and mineralogy using X-ray diffraction. In the present study, we find that all three samples of volcanic ash are excellent depositional ice nuclei, nucleating ice from 225–235 K at ice saturation ratios of 1.05 ± 0.01, comparable to the mineral dust proxy kaolinite. Since depositional ice nucleation will be more important at colder temperatures, fine volcanic ash may represent a global source of cold-cloud ice nuclei. For immersion freezing relevant to mixed-phase clouds, however, only the Oruanui ash exhibited heterogeneous ice nucleation activity. Similar to recent studies on mineral dust, we suggest that the mineralogy of volcanic ash may dictate its ice nucleation activity in the immersion mode.

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Enhanced ice nucleation activity of coal fly ash aerosol particles initiated by ice-filled pores

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-8783-2019 ◽

2019 ◽

Vol 19 (13) ◽

pp. 8783-8800 ◽

Cited By ~ 10

Author(s):

Nsikanabasi Silas Umo ◽

Robert Wagner ◽

Romy Ullrich ◽

Alexei Kiselev ◽

Harald Saathoff ◽

...

Keyword(s):

Coal Fly Ash ◽

Aerosol Particles ◽

Ice Nucleation ◽

Temperature Cycling ◽

Cloud Formation ◽

Ice Formation ◽

Strong Increase ◽

Active Fraction ◽

Nucleation Activity ◽

Ice Nucleation Activity

Abstract. Ice-nucleating particles (INPs), which are precursors for ice formation in clouds, can alter the microphysical and optical properties of clouds, thereby impacting the cloud lifetimes and hydrological cycles. However, the mechanisms with which these INPs nucleate ice when exposed to different atmospheric conditions are still unclear for some particles. Recently, some INPs with pores or permanent surface defects of regular or irregular geometries have been reported to initiate ice formation at cirrus temperatures via the liquid phase in a two-step process, involving the condensation and freezing of supercooled water inside these pores. This mechanism has therefore been labelled pore condensation and freezing (PCF). The PCF mechanism allows formation and stabilization of ice germs in the particle without the formation of macroscopic ice. Coal fly ash (CFA) aerosol particles are known to nucleate ice in the immersion freezing mode and may play a significant role in cloud formation. In our current ice nucleation experiments with a particular CFA sample (CFA_UK), which we conducted in the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) aerosol and cloud simulation chamber at the Karlsruhe Institute of Technology (KIT), Germany, we observed a strong increase (at a threshold relative humidity with respect to ice of 101 %–105 %) in the ice-active fraction for experiments performed at temperatures just below the homogeneous freezing of pure water. This observed strong increase in the ice-active fraction could be related to the PCF mechanism. To further investigate the potential of CFA particles undergoing the PCF mechanism, we performed a series of temperature-cycling experiments in AIDA. The temperature-cycling experiments involve exposing CFA particles to lower temperatures (down to ∼228 K), then warming them up to higher temperatures (238–273 K) before investigating their ice nucleation properties. For the first time, we report the enhancement of the ice nucleation activity of the CFA particles for temperatures up to 263 K, from which we conclude that it is most likely due to the PCF mechanism. This indicates that ice germs formed in the CFA particles' pores during cooling remain in the pores during warming and induce ice crystallization as soon as the pre-activated particles experience ice-supersaturated conditions at higher temperatures; hence, these pre-activated particles show an enhancement in their ice-nucleating ability compared with the scenario where the CFA particles are directly probed at higher temperatures without temporary cooling. The enhancement in the ice nucleation ability showed a positive correlation with the specific surface area and porosity of the particles. On the one hand, the PCF mechanism can play a significant role in mixed-phase cloud formation in a case where the CFA particles are injected from higher altitudes and then transported to lower altitudes after being exposed to lower temperatures. On the other hand, the PCF mechanism could be the prevalent nucleation mode for ice formation at cirrus temperatures rather than the previously acclaimed deposition mode.

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Bio-Surfaces of Frost Resistant Plants as Source of Ice-Nucleating Macromolecules

10.5194/egusphere-egu21-15236 ◽

2021 ◽

Author(s):

Teresa M. Seifried ◽

Paul Bieber ◽

Anna T. Kunert ◽

David G. Schmale III ◽

Karin Whitmore ◽

...

Keyword(s):

Betula Pendula ◽

Field Experiments ◽

Aerosol Particles ◽

Chem Phys ◽

Ice Nucleation ◽

Number Concentration ◽

Silver Birch ◽

Dust Particles ◽

Nucleation Activity ◽

Ice Nucleation Activity

The ice nucleation activity of pollen from silver birch (Betula pendula), pines (e.g. Pinus sylvestris) and other trees has been assigned not only to pollen grains but also to subpollen particles (SPP) and extractable macromolecules, i.e. ice-nucleating macromolecules (INMs) (Pummer et al., 2012). The number concentration of pollen in comparison to other ice-nucleating particles suggests a minor impact to atmospheric cloud glaciation (Hoose et al., 2010). When focusing on macromolecules, the importance of INMs from vegetation, however, needs to be re-evaluated in respect to atmospheric ice nucleation. It has been shown that INMs are present in nearly every tissue of birches (Felgitsch et al., 2018) and furthermore, that the macromolecules are extracted from the surface, when they come into contact with water (Seifried et al., 2020). We hypothesize that extractable INMs from tree surfaces are emitted during rainfall by splash induced emissions and field experiments were performed to evaluate the amount of INMs extracted by rain-droplets. Sampled rainwater, which was splashed off from birch surfaces, revealed INMs in high number concentration (108 cm-2) and can be attributed to the vegetation surface (Seifried et al., 2020). To further investigate emission sources an aerosol sampling tool (including an impinger and an impactor) has been developed and mounted on two rotary-wing drones (Bieber et al., 2020). Aerosol samples were collected in an alpine environment on ground level and above the canopy of birches and pines. We found that the bioaerosol concentration increased after rainfall and collected INMs show a similar onset freezing temperature as birch surface extracts (around -20&#176;C). Microscopic images revealed a fluorescent organic film on aerosol particles, which might be linked to extractable material from bio-surfaces.&#160; We suggest splash induced aerosolization of INMs during rainfall to be an underestimated source for atmospheric cloud glaciation, since INMs can easily be carried on larger aerosol particles, e.g. on SPP or on mineral dust particles.&#160;References:Pummer, B. G., Bauer, H., Bernardi, J., Bleicher, S., and Grothe, H.: Suspendable macromolecules are responsible for ice nucleation activity of birch and conifer pollen, Atmos. Chem. Phys., 12, 2541&#8211;2550, https://doi.org/10.5194/acp-12-2541-2012, 2012.Hoose, C., J. E. Kristj&#225;nsson, and S. M. Burrows.: How important is biological ice nucleation in clouds on a global scale?, Environ. Res. Lett., 5, https://doi.org/10.1088/1748-9326/5/2/024009, 2010.Felgitsch, L., Baloh, P., Burkart, J., Mayr, M., Momken, M. E., Seifried, T. M., Winkler, P., Schmale III, D. G., and Grothe, H.: Birch leaves and branches as a source of ice-nucleating macromolecules, Atmos. Chem. Phys., 18, 16063&#8211;16079, https://doi.org/10.5194/acp-18-16063-2018, 2018.Seifried, T. M., Bieber, P., Felgitsch, L., Vlasich, J., Reyzek, F., Schmale III, D. G., and Grothe, H.: Surfaces of silver birch (Betula pendula) are sources of biological ice nuclei: in vivo and in situ investigations, Biogeosciences, 17, 5655&#8211;5667, https://doi.org/10.5194/bg-17-5655-2020, 2020.Bieber, P.; Seifried, T.M.; Burkart, J.; Gratzl, J.; Kasper-Giebl, A.; Schmale, D.G., III; Grothe, H. A Drone-Based Bioaerosol Sampling System to Monitor Ice Nucleation Particles in the Lower Atmosphere. Remote Sens., 12, 552, 2020.

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