scholarly journals Seasonal variability of Saharan desert dust and ice nucleating particles over Europe

2015 ◽  
Vol 15 (8) ◽  
pp. 4389-4397 ◽  
Author(s):  
L. B. Hande ◽  
C. Engler ◽  
C. Hoose ◽  
I. Tegen
Keyword(s):  
Seasonal Variability ◽  
Mesoscale Model ◽  
Ice Nucleation ◽  
Saharan Dust ◽  
Dust Particles ◽  
Limited Area ◽  
Order Of Magnitude ◽  
Immersion Freezing ◽  
Best Fit ◽  
Normal Background

Abstract. Dust aerosols are thought to be the main contributor to atmospheric ice nucleation. While there are case studies supporting this, a climatological sense of the importance of dust to atmospheric ice nucleating particle (INP) concentrations and its seasonal variability over Europe is lacking. Here, we use a mesoscale model to estimate Saharan dust concentrations over Europe in 2008. There are large differences in median dust concentrations between seasons, with the highest concentrations and highest variability in the lower to mid-troposphere. Laboratory-based ice nucleation parameterisations are applied to these simulated dust number concentrations to calculate the potential INP resulting from immersion freezing and deposition nucleation on these dust particles. The potential INP concentrations increase exponentially with height due to decreasing temperatures in the lower and mid-troposphere. When the ice-activated fraction increases sufficiently, INP concentrations follow the dust particle concentrations. The potential INP profiles exhibit similarly large differences between seasons, with the highest concentrations in spring (median potential immersion INP concentrations nearly 105 m−3, median potential deposition INP concentrations at 120% relative humidity with respect to ice over 105 m−3), about an order of magnitude larger than those in summer. Using these results, a best-fit function is provided to estimate the potential INPs for use in limited-area models, which is representative of the normal background INP concentrations over Europe. A statistical evaluation of the results against field and laboratory measurements indicates that the INP concentrations are in close agreement with observations.

scholarly journals Seasonal variability of Saharan desert dust and ice nucleating particles over Europe

2014 ◽  
Vol 14 (23) ◽  
pp. 32071-32092 ◽  
Author(s):  
L. B. Hande ◽  
C. Engler ◽  
C. Hoose ◽  
I. Tegen
Keyword(s):  
Seasonal Variability ◽  
Mesoscale Model ◽  
Ice Nucleation ◽  
Saharan Dust ◽  
Dust Particles ◽  
Limited Area ◽  
Upper Troposphere ◽  
Immersion Freezing ◽  
Best Fit ◽  
Normal Background

Abstract. Dust aerosols are thought to be the main contributor to atmospheric ice nucleation. While there are case studies supporting this, a climatological sense of the importance of dust to atmospheric ice nucleating particle (INP) concentrations, and it's seasonal variability over Europe is lacking. Here, we use a mesoscale model to estimate Saharan dust concentrations over Europe in winter and summer of 2007–2008. There are large differences in median dust concentrations between seasons, with the highest concentrations and highest variability in the lowest 4 km. Laboratory based ice nucleation parameterisations are applied to these dust number concentrations to calculate the potential INP resulting from immersion freezing and deposition nucleation on these dust particles. The potential INP concentrations generally increase with height due to decreasing temperatures in the lower and mid-troposphere and exhibit a maximum in the upper troposphere where INP concentrations decrease again with altitude due to decreasing dust concentrations. The potential INP profiles exhibit similarly large differences between seasons, with the highest concentrations in winter (median potential immersion INP concentrations up to 103 m−3, median potential deposition INP concentrations at 120% relative humidity with respect to ice up to 105 m−3) occurring closer to the ground for both nucleation modes. Using these results, a best-fit function is provided to estimate the potential INPs for use in limited-area models, which is representative of the normal background INP concentrations over Europe. A statistical evaluation of the results against field and laboratory measurements indicates that the INP concentrations are in close agreement with observations.

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

2018 ◽  
Vol 11 (1) ◽  
pp. 233-248 ◽  
Author(s):  
Naama Reicher ◽  
Lior Segev ◽  
Yinon Rudich
Keyword(s):  
Active Surface ◽  
Ice Nucleation ◽  
Saharan Dust ◽  
Dust Particles ◽  
Active Surface Site ◽  
Immersion Freezing ◽  
Measurement Uncertainties ◽  
Homogeneous Freezing ◽  
Validation Experiments

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.

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

2017 ◽  
Author(s):  
Naama Reicher ◽  
Lior Segev ◽  
Yinon Rudich
Keyword(s):  
Active Surface ◽  
Mineral Oil ◽  
Ice Nucleation ◽  
Saharan Dust ◽  
Dust Particles ◽  
Active Surface Site ◽  
Immersion Freezing ◽  
Measurement Uncertainties ◽  
Validation Experiments

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 homogenous freezing of water (235 K) in various cooling rates (typically 0.1-10 K min−1). It can also be used for studying homogenous freezing of aqueous solutions in colder temperatures. Frozen fraction, ice nucleation active surface site (INAS) densities and freezing kinetics can be obtained from WISDOM measurements with excellent statistics of hundreds of individual droplets in a single freezing experiment. Droplets are surrounded by a mineral oil phase which assures the isolation of the droplets and prevents mutual seeding, mass transfer or evaporation, and hence increases the reliability and reproducibility of the measurement. 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 INP properties of size-selected ambient Saharan dust particles is presented.

scholarly journals A new method for operating a continuous-flow diffusion chamber to investigate immersion freezing: assessment and performance study

2020 ◽  
Vol 13 (12) ◽  
pp. 6631-6643
Author(s):  
Gourihar Kulkarni ◽  
Naruki Hiranuma ◽  
Ottmar Möhler ◽  
Kristina Höhler ◽  
Swarup China ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Diffusion Chamber ◽  
Ice Nucleation ◽  
Radiative Properties ◽  
Dust Particles ◽  
Second Phase ◽  
Soil Dust ◽  
Performance Study ◽  
Order Of Magnitude ◽  
Immersion Freezing

Abstract. Glaciation in mixed-phase clouds predominantly occurs through the immersion-freezing mode where ice-nucleating particles (INPs) immersed within supercooled droplets induce the nucleation of ice. Model representations of this process currently are a large source of uncertainty in simulating cloud radiative properties, so to constrain these estimates, continuous-flow diffusion chamber (CFDC)-style INP devices are commonly used to assess the immersion-freezing efficiencies of INPs. This study explored a new approach to operating such an ice chamber that provides maximum activation of particles without droplet breakthrough and correction factor ambiguity to obtain high-quality INP measurements in a manner that previously had not been demonstrated to be possible. The conditioning section of the chamber was maintained at −20 ∘C and water relative humidity (RHw) conditions of 113 % to maximize the droplet activation, and the droplets were supercooled with an independently temperature-controlled nucleation section at a steady cooling rate (0.5 ∘C min−1) to induce the freezing of droplets and evaporation of unfrozen droplets. The performance of the modified compact ice chamber (MCIC) was evaluated using four INP species: K-feldspar, illite-NX, Argentinian soil dust, and airborne soil dusts from an arable region that had shown ice nucleation over a wide span of supercooled temperatures. Dry-dispersed and size-selected K-feldspar particles were generated in the laboratory. Illite-NX and soil dust particles were sampled during the second phase of the Fifth International Ice Nucleation Workshop (FIN-02) campaign, and airborne soil dust particles were sampled from an ambient aerosol inlet. The measured ice nucleation efficiencies of model aerosols that had a surface active site density (ns) metric were higher but mostly agreed within 1 order of magnitude compared to results reported in the literature.

scholarly journals A new method for operating a continuous flow diffusion chamber to investigate immersion freezing: assessment and performance study

2020 ◽  
Author(s):  
Gourihar Kulkarni ◽  
Naruki Hiranuma ◽  
Ottmar Möhler ◽  
Kristina Höhler ◽  
Swarup China ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Diffusion Chamber ◽  
Ice Nucleation ◽  
Radiative Properties ◽  
Dust Particles ◽  
Second Phase ◽  
Soil Dust ◽  
Performance Study ◽  
Order Of Magnitude ◽  
Immersion Freezing

Abstract. Glaciation in mixed-phase clouds predominately occurs through the immersion freezing mode where ice nucleating particles (INPs) immersed within supercooled droplets induce nucleation of ice. Currently, model representations of this process are a large source of uncertainty in simulating cloud radiative properties, and to constrain these estimates, continuous flow diffusion chamber (CFDC)-style INP devices are commonly used to assess the immersion freezing efficiencies of INPs. In this study, a new approach was explored to operating such an ice chamber that provides maximum activation of particles without droplet breakthrough and correction factor ambiguity to obtain high-quality INP measurements in a manner that has not been demonstrated as possible previously. The conditioning section of the chamber was maintained at ~ −20 °C and water relative humidity (RHw) ~ 113 % conditions to maximize the droplet activation, and the droplets were supercooled with an independently temperature-controlled nucleation section at a steady cooling rate (0.5 °C min−1) to induce the freezing of droplets and evaporation of unfrozen droplets. The performance of the modified ice chamber was evaluated using four INP species: K-feldspar, illite-NX, Argentinian soil dust, and airborne arable dust that had shown ice nucleation over a wide span of supercooled temperatures. Dry dispersed and size-selected K-feldspar particles were generated in the laboratory. Illite-NX and soil dust particles were sampled during the second phase of the Fifth International Ice Nucleation Workshop (FIN-02) campaign, and airborne arable dust particles were sampled from the aerosol inlet located on the rooftop of the laboratory. The measured ice nucleation efficiencies of model aerosols with a surface active site density (ns) metric were higher, but mostly agreed within one order of magnitude compared to literature results.

scholarly journals Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles

2015 ◽  
Vol 15 (1) ◽  
pp. 393-409 ◽  
Author(s):  
P. J. DeMott ◽  
A. J. Prenni ◽  
G. R. McMeeking ◽  
R. C. Sullivan ◽  
M. D. Petters ◽  
...  
Keyword(s):  
Mineral Dust ◽  
Order Approximation ◽  
Ice Nucleation ◽  
Calibration Factor ◽  
Dust Particles ◽  
Single Type ◽  
Aerosol Layer ◽  
Atmospheric Measurements ◽  
Immersion Freezing ◽  
Nucleation Activity

Abstract. Data from both laboratory studies and atmospheric measurements are used to develop an empirical parameterization for the immersion freezing activity of natural mineral dust particles. Measurements made with the Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing mineral dust aerosols at a nominal 105% relative humidity with respect to water (RHw) are taken as a measure of the immersion freezing nucleation activity of particles. Ice active frozen fractions vs. temperature for dusts representative of Saharan and Asian desert sources were consistent with similar measurements in atmospheric dust plumes for a limited set of comparisons available. The parameterization developed follows the form of one suggested previously for atmospheric particles of non-specific composition in quantifying ice nucleating particle concentrations as functions of temperature and the total number concentration of particles larger than 0.5 μm diameter. Such an approach does not explicitly account for surface area and time dependencies for ice nucleation, but sufficiently encapsulates the activation properties for potential use in regional and global modeling simulations, and possible application in developing remote sensing retrievals for ice nucleating particles. A calibration factor is introduced to account for the apparent underestimate (by approximately 3, on average) of the immersion freezing fraction of mineral dust particles for CSU CFDC data processed at an RHw of 105% vs. maximum fractions active at higher RHw. Instrumental factors that affect activation behavior vs. RHw in CFDC instruments remain to be fully explored in future studies. Nevertheless, the use of this calibration factor is supported by comparison to ice activation data obtained for the same aerosols from Aerosol Interactions and Dynamics of the Atmosphere (AIDA) expansion chamber cloud parcel experiments. Further comparison of the new parameterization, including calibration correction, to predictions of the immersion freezing surface active site density parameterization for mineral dust particles, developed separately from AIDA experimental data alone, shows excellent agreement for data collected in a descent through a Saharan aerosol layer. These studies support the utility of laboratory measurements to obtain atmospherically relevant data on the ice nucleation properties of dust and other particle types, and suggest the suitability of considering all mineral dust as a single type of ice nucleating particle as a useful first-order approximation in numerical modeling investigations.

scholarly journals A comprehensive characterization of ice nucleation by three different types of cellulose particles immersed in water

2019 ◽  
Vol 19 (7) ◽  
pp. 4823-4849 ◽  
Author(s):  
Naruki Hiranuma ◽  
Kouji Adachi ◽  
David M. Bell ◽  
Franco Belosi ◽  
Hassan Beydoun ◽  
...  
Keyword(s):  
Aqueous Suspension ◽  
Measurement Techniques ◽  
Active Surface ◽  
Ice Nucleation ◽  
Accuracy And Precision ◽  
Active Surface Site ◽  
Two Samples ◽  
Order Of Magnitude ◽  
Immersion Freezing ◽  
T Values

Abstract. We present the laboratory results of immersion freezing efficiencies of cellulose particles at supercooled temperature (T) conditions. Three types of chemically homogeneous cellulose samples are used as surrogates that represent supermicron and submicron ice-nucleating plant structural polymers. These samples include microcrystalline cellulose (MCC), fibrous cellulose (FC) and nanocrystalline cellulose (NCC). Our immersion freezing dataset includes data from various ice nucleation measurement techniques available at 17 different institutions, including nine dry dispersion and 11 aqueous suspension techniques. With a total of 20 methods, we performed systematic accuracy and precision analysis of measurements from all 20 measurement techniques by evaluating T-binned (1 ∘C) data over a wide T range (−36 ∘C <T<-4 ∘C). Specifically, we intercompared the geometric surface area-based ice nucleation active surface site (INAS) density data derived from our measurements as a function of T, ns,geo(T). Additionally, we also compared the ns,geo(T) values and the freezing spectral slope parameter (Δlog(ns,geo)/ΔT) from our measurements to previous literature results. Results show all three cellulose materials are reasonably ice active. The freezing efficiencies of NCC samples agree reasonably well, whereas the diversity for the other two samples spans ≈ 10 ∘C. Despite given uncertainties within each instrument technique, the overall trend of the ns,geo(T) spectrum traced by the T-binned average of measurements suggests that predominantly supermicron-sized cellulose particles (MCC and FC) generally act as more efficient ice-nucleating particles (INPs) than NCC with about 1 order of magnitude higher ns,geo(T).

Influence of organic and biogenic substances on the ice nucleation properties of mineral dust particles

2020 ◽  
Author(s):  
Kristian Klumpp ◽  
Claudia Marcolli ◽  
Thomas Peter
Keyword(s):  
Amino Acids ◽  
Organic Acids ◽  
Mineral Dust ◽  
Particle Surface ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Biogenic Substances ◽  
Immersion Freezing ◽  
Mixed Phase Clouds ◽  
Ice Nucleation Activity

&lt;p&gt;The formation of ice in mixed phase clouds occurs in the presence of aerosol particles with the ability to nucleate ice on their surface. These ice-nucleating particles (INPs) represent usually a small fraction of particles in an atmospheric aerosol. One of the main particle types which act as INPs are mineral dust particles. Among other factors, the accumulation of semivolatile substances on the particle surface can alter the ice nucleation properties of such particles.&lt;/p&gt;&lt;p&gt;In recent immersion freezing experiments, we investigated the influence of organic acids, amino acids and polyols on the highly ice nucleation active K-feldspar microcline. Microcline dust was suspended in solutions of the above-mentioned substances and frozen in a differential scanning calorimeter (DSC). These experiments give us insight into the ice nucleation characteristics of the particles in the presence of the tested organic and biogenic substances. Our measurements show an overall decrease in ice nucleation activity of microcline in the presence of organic acids and amino acids. &lt;br&gt;&lt;br&gt;&lt;/p&gt;

scholarly journals Ice nucleation properties of fine ash particles from the Eyjafjallajökull eruption in April 2010

2011 ◽  
Vol 11 (6) ◽  
pp. 17665-17698 ◽  
Author(s):  
I. Steinke ◽  
O. Möhler ◽  
A. Kiselev ◽  
M. Niemand ◽  
H. Saathoff ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Active Surface ◽  
Ice Nucleation ◽  
Saharan Dust ◽  
Surface Site ◽  
Ice Nuclei ◽  
Active Surface Site ◽  
Mineral Dusts ◽  
Immersion Freezing ◽  
Ice Fraction

Abstract. During the eruption of the Eyjafjallajökull volcano in the south of Iceland in April/May 2010, about 40 Tg of ash mass were emitted into the atmosphere. However, it was unclear whether volcanic ash particles with d < 10 μm facilitate the glaciation of clouds. Thus, ice nucleation properties of volcanic ash particles were investigated in AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber experiments simulating atmospherically relevant conditions. The ash sample that was used for our experiments had been collected at a distance of 58 km from the Eyjafjallajökull during the eruption period in April 2010. The temperature range covered by our ice nucleation experiments extended from 219 to 264 K, and both ice nucleation via immersion freezing and deposition nucleation could be observed. Immersion freezing was first observed at 252 K, whereas the deposition nucleation onset lay at 242 K and RHice = 126 %. About 0.1 % of the volcanic ash particles were active as immersion freezing nuclei at a temperature of 249 K. For deposition nucleation, an ice fraction of 0.1 % was observed at around 233 K and RHice = 116 %. Taking ice-active surface site densities as a measure for the ice nucleation efficiency, volcanic ash particles are similarly efficient ice nuclei in immersion freezing mode (ns, imm ~ 109 m−2 at 247 K) compared to certain mineral dusts. For deposition nucleation, the observed ice-active surface site densities ns, dep were found to be 1011 m−2 at 224 K and RHice = 116 %. Thus, volcanic ash particles initiate deposition nucleation more efficiently than Asian and Saharan dust but appear to be poorer ice nuclei than ATD particles. Based on the experimental data, we have derived ice-active surface site densities as a function of temperature for immersion freezing and of relative humidity over ice and temperature for deposition nucleation.

Ice nucleating particle concentrations in Dust Regional Atmospheric Model (DREAM) – going one step further

2021 ◽  
Author(s):  
Luka Ilić ◽  
Eleni Marinou ◽  
Aleksandar Jovanović ◽  
Maja Kuzmanoski ◽  
Slobodan Ničković
Keyword(s):  
Field Experiments ◽  
Mineral Dust ◽  
Atmospheric Model ◽  
Dust Concentration ◽  
Saharan Dust ◽  
Dust Particles ◽  
Vertical Profiles ◽  
Regional Atmospheric Model ◽  
Immersion Freezing ◽  
The Mediterranean

&lt;p&gt;Mineral dust particles in the atmosphere have a large influence on the physical properties of clouds and their lifecycle. Findings from field experiments, modeling, and laboratory studies suggest that mineral dust particles are very efficient ice-nucleating particles (INPs) even in regions distant from the desert sources. The major sources of mineral dust present in the Mediterranean basin are located in the Sahara Desert. Understanding the significance of mineral dust in ice initiation led to the development of INPC parameterizations in presence of dust for immersion freezing and deposition nucleation processes. These parameterizations were mineralogically indifferent, estimating the dust ice nucleating particle concentrations (INPCs) based on dust concentration and thermodynamic parameters. In recent studies, feldspar and quartz minerals have shown to be significantly more efficient INPs than other minerals found in dust. These findings led to the development of mineralogy-sensitive immersion freezing parameterizations. In this study, we implement mineralogy-sensitive and mineralogically-indifferent INPC parameterizations into a regional coupled atmosphere-dust numerical model. We use the Dust Regional Atmospheric Model (DREAM) to perform one month of simulations of the atmospheric cycle of dust and its feldspar and quartz fractions during Saharan dust intrusion events in the Mediterranean. EARLINET (European Aerosol Lidar Network) and AERONET (AErosol RObotic NETwork) measurements are used with POLIPHON algorithm (Polarization Lidar Photometer Networking) to derive cloud-relevant dust concentration profiles. We compare DREAM results with lidar-based vertical profiles of dust mass concentration, surface area concentration, number concentration, and INPCs. This analysis is a step towards the systematic analysis of dust concentration and INPC parameterizations performance when compared to lidar derived vertical profiles.&lt;/p&gt;

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