scholarly journals Best practices for precipitation sample storage for offline studies of ice nucleation

2020 ◽  
Author(s):  
Charlotte M. Beall ◽  
Dolan Lucero ◽  
Thomas C. Hill ◽  
Paul J. DeMott ◽  
M. Dale Stokes ◽  
...  
Keyword(s):  
Room Temperature ◽  
Storage Time ◽  
Ice Nucleation ◽  
Correction Factors ◽  
Ice Crystal ◽  
Phase Partitioning ◽  
Cloud Properties ◽  
Precipitation Sample ◽  
Order Of Magnitude ◽  
La Jolla

Abstract. Ice nucleating particles (INPs) are efficiently removed from clouds through precipitation, a convenience of nature for the study of these very rare particles that influence multiple climate-relevant cloud properties including ice crystal concentrations, size distributions, and phase-partitioning processes. INPs suspended in precipitation can be used to estimate in-cloud INP concentrations and to infer their original composition. Offline droplet assays are commonly used to measure INP concentrations in precipitation samples. Heat and filtration treatments are also used to probe INP composition and size ranges. Many previous studies report storing samples prior to INP analyses, but little is known about the effects of storage on INP concentration or their sensitivity to treatments. Here, through a study of 15 precipitation samples collected at a coastal location in La Jolla, CA, USA, we found significant changes caused by storage to concentrations of INPs with warm to moderate freezing temperatures (−7 to −19 ºC). We compared four conditions: 1.) storage at room temperature (+21–23 ºC), 2.) storage at +4 ºC 3.) storage at −20 ºC, and 4.) flash freezing samples with liquid nitrogen prior to storage at −20 ºC. Results demonstrate that storage can lead to both enhancements and losses of greater than one order of magnitude, with non-heat-labile INPs being generally less sensitive to storage regime, but significant losses of INPs smaller than 0.45 μm in all tested storage protocols. No correlation was found between total storage time (1–166 days) and changes in INP concentration. We provide the following recommendations for preservation of precipitation samples from coastal environments intended for INP analysis: that samples be stored at −20 ºC to minimize storage artifacts, that changes due to storage are likely and an additional uncertainty in INP concentrations, and that filtration treatments be applied only to fresh samples. Average INP losses of 72 %, 42 %, 25 % and 32 % were observed for untreated samples stored using the room temperature, +4 ºC, −20 ºC, and flash frozen protocols, respectively. Finally, correction factors are provided so that INP measurements obtained from stored samples may be used to estimate concentrations in fresh samples.

scholarly journals Best practices for precipitation sample storage for offline studies of ice nucleation in marine and coastal environments

2020 ◽  
Vol 13 (12) ◽  
pp. 6473-6486
Author(s):  
Charlotte M. Beall ◽  
Dolan Lucero ◽  
Thomas C. Hill ◽  
Paul J. DeMott ◽  
M. Dale Stokes ◽  
...  
Keyword(s):  
Room Temperature ◽  
Freezing Temperature ◽  
Phase Partitioning ◽  
Cloud Properties ◽  
Precipitation Sample ◽  
Sampling Protocols ◽  
Order Of Magnitude ◽  
Concentration Changes ◽  
Freezing Temperatures ◽  
La Jolla

Abstract. Ice-nucleating particles (INPs) are efficiently removed from clouds through precipitation, a convenience of nature for the study of these very rare particles that influence multiple climate-relevant cloud properties including ice crystal concentrations, size distributions and phase-partitioning processes. INPs suspended in precipitation can be used to estimate in-cloud INP concentrations and to infer their original composition. Offline droplet assays are commonly used to measure INP concentrations in precipitation samples. Heat and filtration treatments are also used to probe INP composition and size ranges. Many previous studies report storing samples prior to INP analyses, but little is known about the effects of storage on INP concentration or their sensitivity to treatments. Here, through a study of 15 precipitation samples collected at a coastal location in La Jolla, CA, USA, we found INP concentration changes up to > 1 order of magnitude caused by storage to concentrations of INPs with warm to moderate freezing temperatures (−7 to −19 ∘C). We compared four conditions: (1) storage at room temperature (+21–23 ∘C), (2) storage at +4 ∘C, (3) storage at −20 ∘C and (4) flash-freezing samples with liquid nitrogen prior to storage at −20 ∘C. Results demonstrate that storage can lead to both enhancements and losses of greater than 1 order of magnitude, with non-heat-labile INPs being generally less sensitive to storage regime, but significant losses of INPs smaller than 0.45 µm in all tested storage protocols. Correlations between total storage time (1–166 d) and changes in INP concentrations were weak across sampling protocols, with the exception of INPs with freezing temperatures ≥ −9 ∘C in samples stored at room temperature. We provide the following recommendations for preservation of precipitation samples from coastal or marine environments intended for INP analysis: that samples be stored at −20 ∘C to minimize storage artifacts, that changes due to storage are likely an additional uncertainty in INP concentrations, and that filtration treatments be applied only to fresh samples. At the freezing temperature −11 ∘C, average INP concentration losses of 51 %, 74 %, 16 % and 41 % were observed for untreated samples stored using the room temperature, +4, −20 ∘C, and flash-frozen protocols, respectively. Finally, the estimated uncertainties associated with the four storage protocols are provided for untreated, heat-treated and filtered samples for INPs between −9 and −17 ∘C.

scholarly journals A comprehensive parameterization of heterogeneous ice nucleation of dust surrogate: laboratory study with hematite particles and its application to atmospheric models

2014 ◽  
Vol 14 (11) ◽  
pp. 16493-16528 ◽  
Author(s):  
N. Hiranuma ◽  
M. Paukert ◽  
I. Steinke ◽  
K. Zhang ◽  
G. Kulkarni ◽  
...  
Keyword(s):  
Ice Nucleation ◽  
Dust Particles ◽  
Ice Crystal ◽  
Atmospheric Models ◽  
Experimental Conditions ◽  
Cloud Properties ◽  
Ice Nuclei ◽  
Cloud Models ◽  
Order Of Magnitude ◽  
Heterogeneous Ice Nucleation

Abstract. A new heterogeneous ice nucleation parameterization that covers a wide temperature range (−36 to −78 °C) is presented. Developing and testing such an ice nucleation parameterization, which is constrained through identical experimental conditions, is critical in order to accurately simulate the ice nucleation processes in cirrus clouds. The surface-scaled ice nucleation efficiencies of hematite particles, inferred by ns, were derived from AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber measurements under water subsaturated conditions that were realized by continuously changing temperature (T) and relative humidity with respect to ice (RHice) in the chamber. Our measurements showed several different pathways to nucleate ice depending on T and RHice conditions. For instance, almost T-independent freezing was observed at −60 °C < T < −50 °C, where RHice explicitly controlled ice nucleation efficiency, while both T and RHice played roles in other two T regimes: −78 °C < T < −60 °C and −50 °C < T < −36 °C. More specifically, observations at T colder than −60 °C revealed that higher RHice was necessary to maintain constant ns, whereas T may have played a significant role in ice nucleation at T warmer than −50 °C. We implemented new ns parameterizations into two cloud models to investigate its sensitivity and compare with the existing ice nucleation schemes towards simulating cirrus cloud properties. Our results show that the new AIDA-based parameterizations lead to an order of magnitude higher ice crystal concentrations and inhibition of homogeneous nucleation in colder temperature regions. Our cloud simulation results suggest that atmospheric dust particles that form ice nuclei at lower temperatures, below −36 °C, can potentially have stronger influence on cloud properties such as cloud longevity and initiation when compared to previous parameterizations.

scholarly journals Direct comparisons of ice cloud macro- and microphysical properties simulated by the Community Atmosphere Model version 5 with HIPPO aircraft observations

2017 ◽  
Vol 17 (7) ◽  
pp. 4731-4749 ◽  
Author(s):  
Chenglai Wu ◽  
Xiaohong Liu ◽  
Minghui Diao ◽  
Kai Zhang ◽  
Andrew Gettelman ◽  
...  
Keyword(s):  
Nucleation And Growth ◽  
Ice Nucleation ◽  
Ice Crystal ◽  
Ice Clouds ◽  
Model Version ◽  
Microphysical Properties ◽  
Cloud Properties ◽  
Community Atmosphere Model ◽  
Atmosphere Model ◽  
Ice Water

Abstract. In this study we evaluate cloud properties simulated by the Community Atmosphere Model version 5 (CAM5) using in situ measurements from the HIAPER Pole-to-Pole Observations (HIPPO) campaign for the period of 2009 to 2011. The modeled wind and temperature are nudged towards reanalysis. Model results collocated with HIPPO flight tracks are directly compared with the observations, and model sensitivities to the representations of ice nucleation and growth are also examined. Generally, CAM5 is able to capture specific cloud systems in terms of vertical configuration and horizontal extension. In total, the model reproduces 79.8 % of observed cloud occurrences inside model grid boxes and even higher (94.3 %) for ice clouds (T ≤ −40 °C). The missing cloud occurrences in the model are primarily ascribed to the fact that the model cannot account for the high spatial variability of observed relative humidity (RH). Furthermore, model RH biases are mostly attributed to the discrepancies in water vapor, rather than temperature. At the micro-scale of ice clouds, the model captures the observed increase of ice crystal mean sizes with temperature, albeit with smaller sizes than the observations. The model underestimates the observed ice number concentration (Ni) and ice water content (IWC) for ice crystals larger than 75 µm in diameter. Modeled IWC and Ni are more sensitive to the threshold diameter for autoconversion of cloud ice to snow (Dcs), while simulated ice crystal mean size is more sensitive to ice nucleation parameterizations than to Dcs. Our results highlight the need for further improvements to the sub-grid RH variability and ice nucleation and growth in the model.

scholarly journals Modeling of Aircraft Measurements of Ice Crystal Concentration in the Arctic and a Parameterization for Mixed-Phase Cloud

2017 ◽  
Vol 74 (11) ◽  
pp. 3799-3814 ◽  
Author(s):  
Songmiao Fan ◽  
Daniel A. Knopf ◽  
Andrew J. Heymsfield ◽  
Leo J. Donner
Keyword(s):  
Nucleation Rate ◽  
Large Scale ◽  
Weather Forecasting ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
The Arctic ◽  
Dust Particles ◽  
Aircraft Measurements ◽  
Ice Crystal ◽  
Phase Partitioning

Abstract In this study, two parameterizations of ice nucleation rate on dust particles are used in a parcel model to simulate aircraft measurements of ice crystal number concentration Ni in the Arctic. The parcel model has detailed microphysics for droplet and ice nucleation, growth, and evaporation with prescribed vertical air velocities. Three dynamic regimes are considered, including large-scale ascent, cloud-top generating cells, and their combination. With observed meteorological conditions and aerosol concentrations, the parcel model predicts the number concentrations of size-resolved ice crystals, which may be compared to aircraft measurements. Model results show rapid changes with height/time in relative humidity, Ni, and thermodynamic phase partitioning, which is not resolved in current climate and weather forecasting models. Parameterizations for ice number and nucleation rate in mixed-phase stratus clouds are thus developed based on the parcel model results to represent the time-integrated effect of some microphysical processes in large-scale models.

scholarly journals Estimating collision efficiencies from contact freezing experiments

2015 ◽  
Vol 15 (8) ◽  
pp. 12167-12212
Author(s):  
B. Nagare ◽  
C. Marcolli ◽  
O. Stetzer ◽  
U. Lohmann
Keyword(s):  
Atmospheric Aerosols ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Ice Nucleation ◽  
Brownian Diffusion ◽  
Water Droplets ◽  
Collision Efficiency ◽  
Contact Mode ◽  
Cloud Properties ◽  
Order Of Magnitude

Abstract. Interactions of atmospheric aerosols with clouds influence cloud properties and modify the aerosol life cycle. Aerosol particles act as cloud condensation nuclei and ice nucleating particles or become incorporated into cloud droplets by scavenging. For an accurate description of aerosol scavenging and ice nucleation in contact mode, collision efficiency between droplets and aerosol particles needs to be known. This study derives the collision rate from experimental contact freezing data obtained with the ETH Collision Ice Nucleation Chamber CLINCH. Freely falling 80 μm water droplets are exposed to an aerosol consisting of 200 nm diameter silver iodide particles of concentrations from 500–5000 cm−3, which act as ice nucleating particles in contact mode. The chamber is kept at ice saturation in the temperature range from 236–261 K leading to slow evaporation of water droplets giving rise to thermophoresis and diffusiophoresis. Droplets and particles bear charges inducing electrophoresis. The experimentally derived collision efficiency of 0.13 is around one order of magnitude higher than theoretical formulations which include Brownian diffusion, impaction, interception, thermophoretic, diffusiophoretic and electric forces. This discrepancy is most probably due to uncertainties and inaccuracies in the description of thermophoretic and diffusiophoretic processes acting together. This is to the authors knowledge the first dataset of collision efficiencies acquired below 273 K. More such experiments with different droplet and particle diameters are needed to improve our understanding of collision processes acting together.

scholarly journals Influence of surface morphology on the immersion mode ice nucleation efficiency of hematite particles

2013 ◽  
Vol 13 (9) ◽  
pp. 23757-23780
Author(s):  
N. Hiranuma ◽  
N. Hoffmann ◽  
A. Kiselev ◽  
A. Dreyer ◽  
K. Zhang ◽  
...  
Keyword(s):  
Active Sites ◽  
Chemical Properties ◽  
Atmospheric Model ◽  
Substantial Effect ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Ice Crystal ◽  
Surface Irregularities ◽  
Order Of Magnitude ◽  
Expansion Cooling

Abstract. In this paper, the effect of the morphological modification of aerosol particles with respect to heterogeneous ice nucleation is comprehensively investigated for laboratory-generated hematite particles as a model substrate for atmospheric dust particles. The surface area-scaled ice nucleation efficiencies of monodisperse cubic hematite particles and milled hematite particles were measured with a series of expansion cooling experiments using the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud simulation chamber. Complementary off-line characterization of physico-chemical properties of both hematite subsets were also carried out with scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, dynamic light scattering (DLS), and an electro-kinetic particle charge detector to further constrain droplet-freezing measurements of hematite particles. Additionally, an empirical parameterization derived from our laboratory measurements was implemented in the single-column version of the Community Atmospheric Model version 5 (CAM5) to investigate the model sensitivity in simulated ice crystal number concentration on different ice nucleation efficiencies. From an experimental perspective, our results show that the immersion mode ice nucleation efficiency of milled hematite particles is almost an order of magnitude higher at −35.2 °C < T < −33.5 °C than that of the cubic hematite particles, indicating a substantial effect of morphological irregularities on immersion mode freezing. Our modeling results similarly show that the increased droplet-freezing rates of milled hematite particles lead to about one order magnitude higher ice crystal number in the upper troposphere than cubic hematite particles. Overall, our results suggest that the surface irregularities and associated active sites lead to greater ice activation through droplet-freezing.

scholarly journals Direct comparisons of ice cloud macro- and microphysical properties simulated by the Community Atmosphere Model version 5 with HIPPO aircraft observations

2017 ◽  
Author(s):  
Chenglai Wu ◽  
Xiaohong Liu ◽  
Minghui Diao ◽  
Kai Zhang ◽  
Andrew Gettelman ◽  
...  
Keyword(s):  
Nucleation And Growth ◽  
Ice Nucleation ◽  
Ice Crystal ◽  
Ice Clouds ◽  
Model Version ◽  
Microphysical Properties ◽  
Cloud Properties ◽  
Community Atmosphere Model ◽  
Atmosphere Model ◽  
Ice Water

Abstract. In this study we evaluate cloud properties simulated by the Community Atmosphere Model Version 5 (CAM5) using in-situ measurements from the HIAPER Pole-to-Pole Observations (HIPPO) for the period of 2009 to 2011. The modeled wind and temperature are nudged towards reanalysis. Model results collocated with HIPPO flight tracks are directly compared with the observations, and model sensitivities to the representations of ice nucleation and growth are also examined. Generally, CAM5 is able to capture specific cloud systems in terms of vertical configuration and horizontal extension. In total, the model reproduces 79.8 % of observed cloud occurrences inside model grid boxes, and even higher (94.3 %) for ice clouds (T ≤ −40 °C). The missing cloud occurrences in the model are primarily ascribed to the fact that the model cannot account for the high spatial variability of observed relative humidity (RH). Furthermore, model RH biases are mostly attributed to the discrepancies in water vapor, rather than temperature. At the micro-scale of ice clouds, the model captures the observed increase of ice crystal mean sizes with temperature, albeit with smaller sizes than the observations. The model underestimates the observed ice number concentration (Ni) and ice water content (IWC) for ice crystals larger than 75 μm in diameter. Modeled IWC and Ni are more sensitive to the threshold diameter for autoconversion of cloud ice to snow (Dcs), while simulated ice crystal mean size is more sensitive to ice nucleation parameterizations than to Dcs. Our results highlight the need for further improvements to the sub-grid RH variability and ice nucleation and growth in the model.

scholarly journals Influence of surface morphology on the immersion mode ice nucleation efficiency of hematite particles

2014 ◽  
Vol 14 (5) ◽  
pp. 2315-2324 ◽  
Author(s):  
N. Hiranuma ◽  
N. Hoffmann ◽  
A. Kiselev ◽  
A. Dreyer ◽  
K. Zhang ◽  
...  
Keyword(s):  
Active Sites ◽  
Chemical Properties ◽  
Atmospheric Model ◽  
Substantial Effect ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Ice Crystal ◽  
Surface Irregularities ◽  
Order Of Magnitude ◽  
Expansion Cooling

Abstract. In this paper, the effect of the morphological modification of aerosol particles with respect to heterogeneous ice nucleation is comprehensively investigated for laboratory-generated hematite particles as a model substrate for atmospheric dust particles. The surface-area-scaled ice nucleation efficiencies of monodisperse cubic hematite particles and milled hematite particles were measured with a series of expansion cooling experiments using the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud simulation chamber. Complementary offline characterization of physico-chemical properties of both hematite subsets were also carried out with scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, dynamic light scattering (DLS), and an electro-kinetic particle charge detector to further constrain droplet-freezing measurements of hematite particles. Additionally, an empirical parameterization derived from our laboratory measurements was implemented in the single-column version of the Community Atmospheric Model version 5 (CAM5) to investigate the model sensitivity in simulated ice crystal number concentration on different ice nucleation efficiencies. From an experimental perspective, our results show that the immersion mode ice nucleation efficiency of milled hematite particles is almost an order of magnitude higher at −35.2 °C < T < −33.5 °C than that of the cubic hematite particles, indicating a substantial effect of morphological irregularities on immersion mode freezing. Our modeling results similarly show that the increased droplet-freezing rates of milled hematite particles lead to about one order magnitude higher ice crystal number in the upper troposphere than cubic hematite particles. Overall, our results suggest that the surface irregularities and associated active sites lead to greater ice activation through droplet freezing.

scholarly journals A comprehensive parameterization of heterogeneous ice nucleation of dust surrogate: laboratory study with hematite particles and its application to atmospheric models

2014 ◽  
Vol 14 (23) ◽  
pp. 13145-13158 ◽  
Author(s):  
N. Hiranuma ◽  
M. Paukert ◽  
I. Steinke ◽  
K. Zhang ◽  
G. Kulkarni ◽  
...  
Keyword(s):  
Active Surface ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Atmospheric Dust ◽  
Experimental Conditions ◽  
Cloud Properties ◽  
Cloud Models ◽  
Order Of Magnitude ◽  
Lower Temperature ◽  
Heterogeneous Ice Nucleation

Abstract. A new heterogeneous ice nucleation parameterization that covers a wide temperature range (−36 to −78 °C) is presented. Developing and testing such an ice nucleation parameterization, which is constrained through identical experimental conditions, is important to accurately simulate the ice nucleation processes in cirrus clouds. The ice nucleation active surface-site density (ns) of hematite particles, used as a proxy for atmospheric dust particles, were derived from AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber measurements under water subsaturated conditions. These conditions were achieved by continuously changing the temperature (T) and relative humidity with respect to ice (RHice) in the chamber. Our measurements showed several different pathways to nucleate ice depending on T and RHice conditions. For instance, almost T-independent freezing was observed at −60 °C < T < −50 °C, where RHice explicitly controlled ice nucleation efficiency, while both T and RHice played roles in other two T regimes: −78 °C < T < −60 °C and −50 °C < T < −36 °C. More specifically, observations at T lower than −60 °C revealed that higher RHice was necessary to maintain a constant ns, whereas T may have played a significant role in ice nucleation at T higher than −50 °C. We implemented the new hematite-derived ns parameterization, which agrees well with previous AIDA measurements of desert dust, into two conceptual cloud models to investigate their sensitivity to the new parameterization in comparison to existing ice nucleation schemes for simulating cirrus cloud properties. Our results show that the new AIDA-based parameterization leads to an order of magnitude higher ice crystal concentrations and to an inhibition of homogeneous nucleation in lower-temperature regions. Our cloud simulation results suggest that atmospheric dust particles that form ice nuclei at lower temperatures, below −36 °C, can potentially have a stronger influence on cloud properties, such as cloud longevity and initiation, compared to previous parameterizations.

Luminescence Properties of Europium-Doped Yttrium Oxides Derived from Their Dodecylsulfate-Templated Mesostructure and Nanotube Forms

2003 ◽  
Vol 775 ◽  
Author(s):  
Tsuyoshi Kijima ◽  
Kenichi Iwanaga ◽  
Tomomi Hamasuna ◽  
Shinji Mohri ◽  
Mitsunori Yada ◽  
...  
Keyword(s):  
Room Temperature ◽  
Broad Band ◽  
Concentration Quenching ◽  
Precipitation Method ◽  
Homogeneous Precipitation ◽  
Bulk Materials ◽  
Main Band ◽  
Homogeneous Precipitation Method ◽  
Order Of Magnitude ◽  
Weak Luminescence

AbstractEuropium-doped hexagonal-mesostructured and nanotubular yttrium oxides templated by dodecylsulfate species as well as surfactant free bulk oxides were synthesized by the homogeneous precipitation method. All the as grown nanostructured or bulk materials with amorphous or poorly crystalline frameworks showed weak luminescence bands at room temperature. On calcination at 1000°C these materials were converted into highly crystalline yttrium oxides, resulting in a total increase in intensity of all the bands by one order of magnitude. In the hexagonal-mesostructured system, the main band due to the 5D0-7F2 transition for the calcined phases showed a sharp but asymmetrical multiplet splitting indicating multiple Eu sites. Concentration quenching was found at a Eu content of 3 mol% or above for these phases. In contrast, the main emission for the calcined solids in the nanotubular system occurred as poorly resolved broad band and the intensity of the main band at higher Eu content was significantly enhanced compared with those for the other two systems.

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