scholarly journals Laboratory studies of immersion and deposition mode ice nucleation of ozone aged mineral dust particles

2013 ◽  
Vol 13 (17) ◽  
pp. 9097-9118 ◽  
Author(s):  
Z. A. Kanji ◽  
A. Welti ◽  
C. Chou ◽  
O. Stetzer ◽  
U. Lohmann
Keyword(s):  
Mineral Dust ◽  
Active Surface ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Laboratory Studies ◽  
Ambient Conditions ◽  
First Results ◽  
Deposition Mode ◽  
Heterogeneous Ice Nucleation

Abstract. Ice nucleation in the atmosphere is central to the understanding the microphysical properties of mixed-phase and cirrus clouds. Ambient conditions such as temperature (T) and relative humidity (RH), as well as aerosol properties such as chemical composition and mixing state play an important role in predicting ice formation in the troposphere. Previous field studies have reported the absence of sulfate and organic compounds on mineral dust ice crystal residuals sampled at mountain top stations or aircraft based measurements despite the long-range transport mineral dust is subjected to. We present laboratory studies of ice nucleation for immersion and deposition mode on ozone aged mineral dust particles for 233 < T < 263 K. Heterogeneous ice nucleation of untreated kaolinite (Ka) and Arizona Test Dust (ATD) particles is compared to corresponding aged particles that are subjected to ozone concentrations of 0.4–4.3 ppmv in a stainless steel aerosol tank. The portable ice nucleation counter (PINC) and immersion chamber combined with the Zurich ice nucleation chamber (IMCA-ZINC) are used to conduct deposition and immersion mode measurements, respectively. Ice active fractions as well as ice active surface site densities (ns) are reported and observed to increase as a function of decreasing temperature. We present first results that demonstrate enhancement of the ice nucleation ability of aged mineral dust particles in both the deposition and immersion mode due to ageing. We also present the first results to show a suppression of heterogeneous ice nucleation activity without the condensation of a coating of (in)organic material. In immersion mode, low ozone exposed Ka particles showed enhanced ice activity requiring a median freezing temperature of 1.5 K warmer than that of untreated Ka, whereas high ozone exposed ATD particles showed suppressed ice nucleation requiring a median freezing temperature of 3 K colder than that of untreated ATD. In deposition mode, low exposure Ka had ice active fractions of an order of magnitude higher than untreated Ka, whereas high ozone exposed ATD had ice active fractions up to a factor of 4 lower than untreated ATD. From our results, we derive and present parameterizations in terms of ns(T) that can be used in models to predict ice nuclei concentrations based on available aerosol surface area.

scholarly journals Laboratory studies of immersion and deposition mode ice nucleation of ozone aged mineral dust particles

2013 ◽  
Vol 13 (4) ◽  
pp. 8701-8767 ◽  
Author(s):  
Z. A. Kanji ◽  
A. Welti ◽  
C. Chou ◽  
O. Stetzer ◽  
U. Lohmann
Keyword(s):  
Organic Compounds ◽  
Mineral Dust ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Laboratory Studies ◽  
High Exposure ◽  
First Results ◽  
Low Exposure ◽  
Deposition Mode

Abstract. Ice nucleation in the atmosphere is central to the understanding the microphysical properties of mixed-phase and cirrus clouds. Ambient conditions such as temperature (T) and relative humidity (RH), as well as aerosol properties such as chemical composition and mixing state play an important role in predicting ice formation in the troposphere. Previous field studies have reported the absence of sulphate and organic compounds on mineral dust ice crystal residuals sampled at mountain top stations or aircraft based measurements despite the long range transport mineral dust is subjected to. We present laboratory studies of ice nucleation for immersion and deposition mode on ozone aged mineral dust particles for 233 < T < 263 K that will represent ageing but not internal mixing with in(organic) compounds. Heterogeneous ice nucleation of untreated kaolinite (Ka) and Arizona Test Dust (ATD) particles is compared to corresponding aged particles that are subjected to ozone exposures of 0.4–4.3 ppmv in a stainless steel aerosol tank. The portable ice nucleation counter (PINC) and immersion chamber combined with the Zurich ice nucleation chamber (IMCA – ZINC) are used to conduct deposition and immersion mode measurements respectively. Ice active fractions as well as ice active surface site densities (ns) are reported and observed to increase as a function of temperature. We present first results that demonstrate enhancement of the ice nucleation ability of aged mineral dust particles in both the deposition and immersion mode due to ageing. Additionally, these are also the first results to show a suppression of heterogeneous ice nucleation without the condensation of a coating of (in)organic material. In immersion mode, low exposure Ka particles showed enhanced ice activity requiring a median freezing temperature of 1.5 K warmer than that of untreated Ka whereas high exposure ATD particles showed suppressed ice nucleation requiring a median freezing temperature of 3 K colder than that of untreated ATD. In deposition mode, low exposure Ka had ice active fractions of an order of magnitude higher than untreated Ka, where as high exposure ATD had ice active fractions up to a factor of 4 lower than untreated ATD. Based on our results, we present parameterizations in terms of ns(T) that can represent ice nucleation of atmospherically aged and non-aged particles for both immersion and deposition mode. We find excellent agreement (to within less than a factor of 2) with field measurements when parameterizations derived from our results are used to predict ice nuclei concentrations in the troposphere.

scholarly journals Ice nucleating particles in the Saharan Air Layer

2016 ◽  
Vol 16 (14) ◽  
pp. 9067-9087 ◽  
Author(s):  
Yvonne Boose ◽  
Berko Sierau ◽  
M. Isabel García ◽  
Sergio Rodríguez ◽  
Andrés Alastuey ◽  
...  
Keyword(s):  
Mineral Dust ◽  
Ice Nucleation ◽  
Anthropogenic Sources ◽  
Laboratory Studies ◽  
Atmospheric Measurements ◽  
Desert Dust ◽  
Saharan Air Layer ◽  
Biological Particles ◽  
Condensation Mode ◽  
Deposition Mode

Abstract. This study aims at quantifying the ice nucleation properties of desert dust in the Saharan Air Layer (SAL), the warm, dry and dust-laden layer that expands from North Africa to the Americas. By measuring close to the dust's emission source, before aging processes during the transatlantic advection potentially modify the dust properties, the study fills a gap between in situ measurements of dust ice nucleating particles (INPs) far away from the Sahara and laboratory studies of ground-collected soil. Two months of online INP concentration measurements are presented, which were part of the two CALIMA campaigns at the Izaña observatory in Tenerife, Spain (2373 m a.s.l.), in the summers of 2013 and 2014. INP concentrations were measured in the deposition and condensation mode at temperatures between 233 and 253 K with the Portable Ice Nucleation Chamber (PINC). Additional aerosol information such as bulk chemical composition, concentration of fluorescent biological particles as well as the particle size distribution was used to investigate observed variations in the INP concentration. The concentration of INPs was found to range between 0.2 std L−1 in the deposition mode and up to 2500 std L−1 in the condensation mode at 240 K. It correlates well with the abundance of aluminum, iron, magnesium and manganese (R: 0.43–0.67) and less with that of calcium, sodium or carbonate. These observations are consistent with earlier results from laboratory studies which showed a higher ice nucleation efficiency of certain feldspar and clay minerals compared to other types of mineral dust. We find that an increase of ammonium sulfate, linked to anthropogenic emissions in upwind distant anthropogenic sources, mixed with the desert dust has a small positive effect on the condensation mode INP per dust mass ratio but no effect on the deposition mode INP. Furthermore, the relative abundance of biological particles was found to be significantly higher in INPs compared to the ambient aerosol. Overall, this suggests that atmospheric aging processes in the SAL can lead to an increase in ice nucleation ability of mineral dust from the Sahara. INP concentrations predicted with two common parameterization schemes, which were derived mostly from atmospheric measurements far away from the Sahara but influenced by Asian and Saharan dust, were found to be higher based on the aerosol load than we observed in the SAL, further suggesting aging effects of INPs in the SAL.

scholarly journals Chemical processing does not always impair heterogeneous ice nucleation of mineral dust particles

2010 ◽  
Vol 37 (24) ◽  
pp. n/a-n/a ◽  
Author(s):  
Ryan C. Sullivan ◽  
Lorena Miñambres ◽  
Paul J. DeMott ◽  
Anthony J. Prenni ◽  
Christian M. Carrico ◽  
...  
Keyword(s):  
Mineral Dust ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Chemical Processing ◽  
Heterogeneous Ice Nucleation

scholarly journals Irreversible loss of ice nucleation active sites in mineral dust particles caused by sulphuric acid condensation

2010 ◽  
Vol 10 (23) ◽  
pp. 11471-11487 ◽  
Author(s):  
R. C. Sullivan ◽  
M. D. Petters ◽  
P. J. DeMott ◽  
S. M. Kreidenweis ◽  
H. Wex ◽  
...  
Keyword(s):  
Sulphuric Acid ◽  
Active Sites ◽  
Mineral Dust ◽  
Active Surface ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Ammonia Gas ◽  
Surface Sites ◽  
Active Surface Sites ◽  
Acid Coating

Abstract. During the FROST-2 (FReezing Of duST) measurement campaign conducted at the Leipzig Aerosol Cloud Interaction Simulator (LACIS), we investigated changes in the ice nucleation properties of 300 nm Arizona Test Dust mineral particles following thermochemical processing by varying amounts and combinations of exposure to sulphuric acid vapour, ammonia gas, water vapour, and heat. The processed particles' heterogeneous ice nucleation properties were determined in both the water subsaturated and supersaturated humidity regimes at −30 °C and −25 °C using Colorado State University's continuous flow diffusion chamber. The amount of sulphuric acid coating material was estimated by an aerosol mass spectrometer and from CCN-derived hygroscopicity measurements. The condensation of sulphuric acid decreased the dust particles' ice nucleation ability in proportion to the amount of sulphuric acid added. Heating the coated particles in a thermodenuder at 250 °C – intended to evaporate the sulphuric acid coating – reduced their freezing ability even further. We attribute this behaviour to accelerated acid digestion of ice active surface sites by heat. Exposing sulphuric acid coated dust to ammonia gas produced particles with similarly poor freezing potential; however a portion of their ice nucleation ability could be restored after heating in the thermodenuder. In no case did any combination of thermochemical treatments increase the ice nucleation ability of the coated mineral dust particles compared to unprocessed dust. These first measurements of the effect of identical chemical processing of dust particles on their ice nucleation ability under both water subsaturated and mixed-phase supersaturated cloud conditions revealed that ice nucleation was more sensitive to all coating treatments in the water subsaturated regime. The results clearly indicate irreversible impairment of ice nucleation activity in both regimes after condensation of concentrated sulphuric acid. This implies that the sulphuric acid coating caused permanent chemical and/or physical modification of the ice active surface sites; the possible dissolution of the coating during droplet activation did not restore all immersion/condensation-freezing ability.

scholarly journals Irreversible loss of ice nucleation active sites in mineral dust particles caused by sulphuric acid condensation

2010 ◽  
Vol 10 (7) ◽  
pp. 16901-16940 ◽  
Author(s):  
R. C. Sullivan ◽  
M. D. Petters ◽  
P. J. DeMott ◽  
S. M. Kreidenweis ◽  
H. Wex ◽  
...  
Keyword(s):  
Sulphuric Acid ◽  
Active Sites ◽  
Mineral Dust ◽  
Active Surface ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Ammonia Gas ◽  
Surface Sites ◽  
Active Surface Sites ◽  
Acid Coating

Abstract. During the FROST-2 (FReezing Of duST) measurement campaign conducted at the Leipzig Aerosol Cloud Interaction Simulator (LACIS), we investigated changes in the ice nucleation properties of 300 nm Arizona test dust mineral particles following thermochemical processing by varying amounts and combinations of exposure to sulphuric acid vapour, ammonia gas, water vapour, and heat. The processed aerosol's heterogeneous ice nucleation properties were determined in both the water subsaturated and supersaturated humidity regimes at −30 °C and −25 °C using Colorado State University's continuous flow diffusion chamber. The amount of sulphuric acid coating material was estimated by an aerosol mass spectrometer and from CCN-derived hygroscopicity measurements. The condensation of sulphuric acid decreased the dust particles' ice nucleation ability in proportion to the amount of sulphuric acid added. Heating the coated particles in a thermodenuder at 250 °C – intended to evaporate the sulphuric acid coating – reduced their freezing ability even further. We attribute this behaviour to accelerated acid digestion of ice active surface sites by heat. Exposing sulphuric acid coated dust to ammonia gas produced particles with similarly poor freezing potential; however a portion of their ice nucleation ability could be restored after heating in the thermodenuder. In no case did any combination of thermochemical treatments increase the ice nucleation ability of the coated mineral dust particles compared to unprocessed dust. These first measurements of the effect of identical chemical processing of dust particles on their ice nucleation ability in both water subsaturated and mixed-phase supersaturated cloud conditions revealed that ice nucleation was more sensitive to all coating treatments in the water subsaturated regime. The results clearly indicate irreversible impairment of ice nucleation activity in both regimes after condensation of concentrated sulphuric acid. This implies that the sulphuric acid coating caused permanent chemical and/or physical modification of the ice active surface sites; the possible dissolution of the coating during droplet activation did not restore all immersion/condensation-freezing ability.

Heterogeneous ice nucleation of mineral dust particles exposed to ozone

2013 ◽  
Author(s):  
Zamin A. Kanji ◽  
André Welti ◽  
Cédric Chou ◽  
Olaf Stetzer ◽  
Ulrike Lohmann
Keyword(s):  
Mineral Dust ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Heterogeneous Ice Nucleation

Effect of water confinement on heterogeneous ice nucleation

2020 ◽  
Author(s):  
Olli Pakarinen ◽  
Golnaz Roudsari ◽  
Bernhard Reischl ◽  
Hanna Vehkamäki
Keyword(s):  
Active Sites ◽  
Mineral Dust ◽  
Pure Water ◽  
Wedge Angle ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Small Surface ◽  
Surface Features ◽  
Effect Of Water ◽  
Heterogeneous Ice Nucleation

&lt;p&gt;Understanding the formation of ice is of great importance to many fields of science. Sufficiently pure water droplets can remain in the supercooled liquid phase to nearly -40 &amp;#186;C. Crystallization of ice in the atmosphere therefore typically occurs in the presence of ice nucleating particles (INPs), such as mineral dust or organic particles. These can trigger heterogeneous ice nucleation at clearly higher temperatures. Therefore, a better understanding of how the various types of aerosol particles present in the atmosphere affect ice nucleation (IN) in clouds would be an important advance in the field of atmospheric science.&lt;/p&gt;&lt;p&gt;Experiments have shown in great detail what is the IN activity of different types of compounds, and recently also clarified the importance of small surface features such as surface defects, which function as active sites for ice nucleation. On most mineral dust particles, there may be only a few active sites for ice nucleation, typically around defects or pits (Holden et al., 2019). Simulations also showed enhanced ice nucleation efficiency in confined geometry such as wedges or pits (Bi, Cao and Li, 2017).&lt;/p&gt;&lt;p&gt;We systematically study the effect of water confining defects with different surface geometries; pyramidal pits, wedge-shaped cracks and slits with water confined between two parallel walls, using molecular dynamics simulations with both all-atom and monatomic water models, and show that that these defects enhance ice nucleation both at large supercooling and at very low supercooling.&lt;/p&gt;&lt;p&gt;Results of simulations on pyramidal pits on Si (100) surfaces, realizable experimentally, show a clear (&amp;#8710;T &gt; 10 &amp;#186;C) enhancement of ice nucleation compared to the very weakly IN active flat Si (100) or Si (111) surfaces. To show that water confinement can enhance IN also at very low supercooling, at temperatures above &amp;#8722;10 &amp;#186;C, we constructed wedge shaped structures with &amp;#946;-AgI (0001) surface as one of the two side walls, and slit systems by positioning two &amp;#946;-AgI (0001) slabs to mirror each other to cancel the dipole field from the polar surfaces. Depending on the wedge angle or the relation of the width of the gap between two slabs in the slit systems with the thickness of ice bilayers, ice nucleation can be clearly enhanced or hindered. We also clarify the different mechanisms behind IN enhancement at different geometries.&lt;/p&gt;&lt;p&gt;Understanding the enhanced activity at surface features may enable characterization of ice nucleation active sites on some atmospheric particles, creation of IN active sites at otherwise poorly active materials such as silicon, and also enable enhancing very active IN materials such as AgI, to nucleate ice at nearly zero supercooling.&lt;/p&gt;&lt;p&gt;This work was supported by the Academy of Finland Center of Excellence programme (grant no. 307331) and ARKTIKO project 285067 ICINA, by University of Helsinki, Faculty of Science ATMATH project, by the National Center for Meteorology (NCM), Abu Dhabi, UAE, under the UAE Research Program for Rain Enhancement Science, as well as ERC Grant 692891-DAMOCLES. Supercomputing resources were provided by CSC&amp;#8211;IT Center for Science, Ltd, Finland.&lt;/p&gt;

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.

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