scholarly journals Ice nucleation by soil dusts: relative importance of mineral dust and biogenic components

2013 ◽  
Vol 13 (8) ◽  
pp. 20275-20317 ◽  
Author(s):  
D. O'Sullivan ◽  
B. J. Murray ◽  
T. L. Malkin ◽  
T. Whale ◽  
N. S. Umo ◽  
...  
Keyword(s):  
Ice Nucleation ◽  
Experimental Methodology ◽  
Dust Particles ◽  
Soil Dust ◽  
Source Regions ◽  
Ice Nuclei ◽  
Wide Range ◽  
Mineral Components ◽  
Droplet Sizes ◽  
Biogenic Components

Abstract. Agricultural dust emissions have been estimated to contribute around 20% to the global dust burden. In contrast to dusts from arid source regions, the ice-nucleating abilities of which have been relatively well studied, soil dusts from fertile sources often contain a substantial fraction of organic matter. Using an experimental methodology which is sensitive to a wide range of ice nucleation efficiencies, we have characterised the immersion mode ice-nucleating activities of dusts extracted from fertile soils collected at four locations around England. By controlling droplet sizes, which ranged in volume from 10−12 to 10−6 L, we have been able to determine the ice nucleation behaviour of soil dust particles at temperatures ranging from 267 K (−6 °C) down to the homogeneous limit of freezing at about 237 K (−36 °C). At temperatures above 258 K (−15 °C) we find that the ice-nucleating activity of soil dusts is diminished by heat treatment or digestion with hydrogen peroxide, suggesting that the ice nuclei stem from biogenic components in the soil. However, below 258 K, we find that the ice active site densities tend towards those expected from the mineral components in the soils, suggesting that the inorganic fraction of soil dusts, in particular the K-feldspar fraction, becomes increasingly important in the initiation of the ice phase at lower temperatures. We conclude that although only a relatively minor contributor to the global atmospheric dust burden, the enhanced IN activities of dusts generated from agricultural activities may play an important role in cloud glaciation, particularly at temperatures above 258 K.

scholarly journals Ice nucleation by fertile soil dusts: relative importance of mineral and biogenic components

2014 ◽  
Vol 14 (4) ◽  
pp. 1853-1867 ◽  
Author(s):  
D. O'Sullivan ◽  
B. J. Murray ◽  
T. L. Malkin ◽  
T. F. Whale ◽  
N. S. Umo ◽  
...  
Keyword(s):  
Ice Nucleation ◽  
Experimental Methodology ◽  
Dust Particles ◽  
Soil Dust ◽  
Source Regions ◽  
Ice Nuclei ◽  
Wide Range ◽  
Mineral Components ◽  
Droplet Sizes ◽  
Biogenic Components

Abstract. Agricultural dust emissions have been estimated to contribute around 20% to the global dust burden. In contrast to dusts from arid source regions, the ice-nucleating abilities of which have been relatively well studied, soil dusts from fertile sources often contain a substantial fraction of organic matter. Using an experimental methodology which is sensitive to a wide range of ice nucleation efficiencies, we have characterised the immersion mode ice-nucleating activities of dusts (d < 11 μm) extracted from fertile soils collected at four locations around England. By controlling droplet sizes, which ranged in volume from 10−12 to 10−6 L (concentration = 0.02 to 0.1 wt% dust), we have been able to determine the ice nucleation behaviour of soil dust particles at temperatures ranging from 267 K (−6 °C) down to the homogeneous limit of freezing at about 237 K (−36 °C). At temperatures above 258 K (−15 °C) we find that the ice-nucleating activity of soil dusts is diminished by heat treatment or digestion with hydrogen peroxide, suggesting that a major fraction of the ice nuclei stems from biogenic components in the soil. However, below 258 K, we find that the ice active site densities tend towards those expected from the mineral components in the soils, suggesting that the inorganic fraction of soil dusts, in particular the K-feldspar fraction, becomes increasingly important in the initiation of the ice phase at lower temperatures. We conclude that dusts from agricultural activities could contribute significantly to atmospheric IN concentrations, if such dusts exhibit similar activities to those observed in the current laboratory study.

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 Investigating the role of dust in ice nucleation within clouds and further effects on regional weather system over East Asia – Part I: model development and validation

2017 ◽  
Author(s):  
Lin Su ◽  
Jimmy C.H. Fung
Keyword(s):  
East Asia ◽  
Source Region ◽  
Model Development ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Weather System ◽  
Microphysics Scheme ◽  
Ice Nuclei ◽  
Cloud Ice ◽  
Ice Water

Abstract. The GOCART–Thompson microphysics scheme, which couples the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model and aerosol-aware Thompson microphysics scheme, has been implemented in the Weather Research and Forecast model coupled with Chemistry (WRF-Chem), to quantify and evaluate the effect of dust on the ice nucleation process in the atmosphere by serving as ice nuclei. The performance of the GOCART-Thompson microphysics scheme in simulating the effect of dust in atmospheric ice nucleation is then evaluated over East Asia during spring in 2012, a typical dust-intensive season. Based upon the dust emission reasonably reproduced by WRF-Chem, the effect of dust on atmospheric cloud ice water content is well reproduced. With abundant dust particles serving as ice nuclei, the simulated ice water mixing ratio and ice crystal number concentration increases by one order of magnitude over the dust source region and downwind areas during the investigated period. The comparison with ice water path from satellite observations demonstrated that the simulation of cloud ice profile is substantially improved by applying the GOCART–Thompson microphysics scheme in the simulations. Additional sensitivity experiments are carried out to optimize the parameters in the ice nucleation parameterization in the GOCART–Thompson microphysics scheme, and the results suggest that the calibration factor in the ice nucleation scheme should be set to 3 or 4. Lowering the threshold relative humidity with respect to ice to 100 % for the ice nucleation parameterization leads to further improvement in cloud ice simulation.

scholarly journals Experimental methodology and procedure for SAPPHIRE:a Semi-automatic APParatus for High-voltage Ice nucleation REsearch

2020 ◽  
Author(s):  
Jens-Michael Löwe ◽  
Markus Schremb ◽  
Volker Hinrichsen ◽  
Cameron Tropea
Keyword(s):  
Electric Field ◽  
High Voltage ◽  
Surface Defects ◽  
Ice Nucleation ◽  
Experimental Methodology ◽  
Cloud Formation ◽  
Crystal Formation ◽  
Strong Impact ◽  
Wide Range ◽  
Accuracy And Repeatability

Abstract. Ice nucleation is of great interest for various processes such as cloud formation in the scope of atmospheric research, and icing of airplanes, ships or structures. Ice nucleation research aims to improve the knowledge about the physical mechanisms and, therefore improve the safety and reliability of the applications affected by ice nucleation. Several influencing factors like liquid supercooling or contamination with nucleants, as well as external disturbances such as an electric field or surface defects affect ice nucleation. Especially for ice crystal formation in clouds and icing of high-voltage equipment, an external electric field may have a strong impact on ice nucleation. Although ice nucleation has been widely investigated for numerous conditions, the effect of an electric field on nucleation is not yet completely understood; results reported in literature are even contradictory. In the present study, an advanced experimental approach for the examination of ice nucleation in water droplets exposed to an electric field is demonstrated. It comprises a method for droplet ensemble preparation and an experimental setup, which allows observation of the droplet ensemble during its exposure to well-defined thermal and electric fields, which are both variable over a wide range. The entire approach aims at maximizing the accuracy and repeatability of the experiments in order to enable examination of even the most minor influences on ice nucleation. For that purpose, the boundary conditions the droplet sample is exposed to during the experiment are examined in particular detail using experimental and numerical methods. The methodological capabilities and accuracy have been demonstrated based on several test nucleation experiments without an electric field, indicating almost perfect repeatability.

scholarly journals Small ice particles at slightly supercooled temperatures in tropical maritime convection

2020 ◽  
Vol 20 (6) ◽  
pp. 3895-3904
Author(s):  
Gary Lloyd ◽  
Thomas Choularton ◽  
Keith Bower ◽  
Jonathan Crosier ◽  
Martin Gallagher ◽  
...  
Keyword(s):  
Ice Nucleation ◽  
Dust Particles ◽  
Cumulus Clouds ◽  
Desert Dust ◽  
Ice Nuclei ◽  
Production Processes ◽  
Ice Particles ◽  
Small Crystals ◽  
Vapour Diffusion ◽  
Very High

Abstract. In this paper we show that the origin of the ice phase in tropical cumulus clouds over the sea may occur by primary ice nucleation of small crystals at temperatures just between 0 and −5 ∘C. This was made possible through use of a holographic instrument able to image cloud particles at very high resolution and small size (6 µm). The environment in which the observations were conducted was notable for the presence of desert dust advected over the ocean from the Sahara. However, there is no laboratory evidence to suggest that these dust particles can act as ice nuclei at temperatures warmer than about −10 ∘C, the zone in which the first ice was observed in these clouds. The small ice particles were observed to grow rapidly by vapour diffusion, riming, and possibly through collisions with supercooled raindrops, causing these to freeze and potentially shatter. This in turn leads to the further production of secondary ice in these clouds. Hence, although the numbers of primary ice particles are small, they are very effective in initiating the rapid glaciation of the cloud, altering the dynamics and precipitation production processes.

scholarly journals Ice nucleation by fungal spores from the classes <i>Agaricomycetes</i>, <i>Ustilaginomycetes</i>, and <i>Eurotiomycetes</i>, and the effect on the atmospheric transport of these spores

2014 ◽  
Vol 14 (16) ◽  
pp. 8611-8630 ◽  
Author(s):  
D. I. Haga ◽  
S. M. Burrows ◽  
R. Iannone ◽  
M. J. Wheeler ◽  
R. H. Mason ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
Fungal Spores ◽  
Ice Nucleation ◽  
Polar Regions ◽  
Cumulative Number ◽  
Mushroom Species ◽  
Near Surface ◽  
Ice Nuclei ◽  
Wide Range

Abstract. We studied the ice nucleation properties of 12 different species of fungal spores chosen from three classes: Agaricomycetes, Ustilaginomycetes, and Eurotiomycetes. Agaricomycetes include many types of mushroom species and are widely distributed over the globe. Ustilaginomycetes are agricultural pathogens and have caused widespread damage to crops. Eurotiomycetes are found on all types of decaying material and include important human allergens. We focused on these classes because they are thought to be abundant in the atmosphere and because there is very little information on the ice nucleation ability of these classes of spores in the literature. All of the fungal spores investigated contained some fraction of spores that serve as ice nuclei at temperatures warmer than homogeneous freezing. The cumulative number of ice nuclei per spore was 0.001 at temperatures between −19 °C and −29 °C, 0.01 between −25.5 °C and −31 °C, and 0.1 between −26 °C and −31.5 °C. On average, the order of ice nucleating ability for these spores is Ustilaginomycetes > Agaricomycetes ≃ Eurotiomycetes. The freezing data also suggests that, at temperatures ranging from −20 °C to −25 °C, all of the fungal spores studied here are less efficient ice nuclei compared to Asian mineral dust on a per surface area basis. We used our new freezing results together with data in the literature to compare the freezing temperatures of spores from the phyla Basidiomycota and Ascomycota, which together make up 98% of known fungal species found on Earth. The data show that within both phyla (Ascomycota and Basidiomycota), there is a wide range of freezing properties, and also that the variation within a phylum is greater than the variation between the average freezing properties of the phyla. Using a global chemistry–climate transport model, we investigated whether ice nucleation on the studied spores, followed by precipitation, can influence the transport and global distributions of these spores in the atmosphere. Simulations suggest that inclusion of ice nucleation scavenging of these fungal spores in mixed-phase clouds can decrease the annual mean concentrations of fungal spores in near-surface air over the oceans and polar regions, and decrease annual mean concentrations in the upper troposphere.

scholarly journals Influence of particle size on the ice nucleating ability of mineral dusts

2009 ◽  
Vol 9 (18) ◽  
pp. 6705-6715 ◽  
Author(s):  
A. Welti ◽  
F. Lüönd ◽  
O. Stetzer ◽  
U. Lohmann
Keyword(s):  
Particle Size ◽  
Size Dependence ◽  
Water Saturation ◽  
Mineral Dust ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Ice Nuclei ◽  
Mineral Dusts ◽  
Measured Activation ◽  
Formation Efficiency

Abstract. The recently developed Zurich Ice Nucleation Chamber (ZINC) was used to explore ice nucleation of size-selected mineral dust particles at temperatures between −20°C and −55°C. Four different mineral dust species have been tested: montmorillonite, kaolinite, illite and Arizona test dust (ATD). The selected particle diameters are 100 nm, 200 nm, 400 nm and 800 nm. Relative humidities with respect to ice (RHi) required to activate 1% of the dust particles as ice nuclei (IN) are reported as a function of temperature. An explicit size dependence of the ice formation efficiency has been observed for all dust types. 800 nm particles required the lowest RHi to activate. Deposition nucleation below water saturation was found only below −30°C or −35°C dependent on particle size. Minimum RHi for 1% activation were 105% for illite, kaolinite and montmorillonite at −40°C, respectively 110% for ATD at −45°C. In addition, a possible parameterisation for the measured activation spectra is proposed, which could be used in modeling studies.

scholarly journals Ice nucleation by surrogates for atmospheric mineral dust and mineral dust/sulfate particles at cirrus temperatures

2005 ◽  
Vol 5 (3) ◽  
pp. 3391-3436 ◽  
Author(s):  
C. M. Archuleta ◽  
P. J. DeMott ◽  
S. M. Kreidenweis
Keyword(s):  
Sulfuric Acid ◽  
Relative Humidity ◽  
Mineral Dust ◽  
Aerosol Particles ◽  
Diffusion Chamber ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Nucleation Behavior ◽  
Ice Nuclei ◽  
Homogeneous Freezing

Abstract. This study examines the potential role of some types of mineral dust and mineral dust with sulfuric acid coatings as heterogeneous ice nuclei at cirrus temperatures. Commercially-available nanoscale powder samples of aluminum oxide, alumina-silicate and iron oxide were used as surrogates for atmospheric mineral dust particles, with and without multilayer coverage of sulfuric acid. A sample of Asian dust aerosol particles was also studied. Measurements of ice nucleation were made using a continuous-flow ice-thermal diffusion chamber (CFDC) operated to expose size-selected aerosol particles to temperatures between −45 and −60°C and a range of relative humidity above ice-saturated conditions. Pure metal oxide particles supported heterogeneous ice nucleation at lower relative humidities than those required to homogeneously freeze sulfuric acid solution particles at sizes larger than about 50 nm. The ice nucleation behavior of the same metal oxides coated with sulfuric acid indicate heterogeneous freezing at lower relative humidities than those calculated for homogeneous freezing of the diluted particle coatings. The effect of soluble coatings on the ice activation relative humidity varied with the respective uncoated core particle types, but for all types the heterogeneous freezing rates increased with particle size for the same thermodynamic conditions. For a selected size of 200 nm, the natural mineral dust particles were the most effective ice nuclei tested, supporting heterogeneous ice formation at an ice relative humidity of approximately 135%, irrespective of temperature. Modified homogeneous freezing parameterizations and theoretical formulations are shown to have application to the description of heterogeneous freezing of mineral dust-like particles with soluble coatings.

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.

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