Water Uptake and Optical Properties of Mixed Organic-Inorganic Particles

2021 ◽  
pp. 1-19
Author(s):  
Lucy Nandy ◽  
Yu Yao ◽  
Zhonghua Zheng ◽  
Nicole Riemer
Keyword(s):  
Optical Properties ◽  
Water Uptake ◽  
Inorganic Particles

First global assessment of modelled aerosol hygroscopicity in the context of other aerosol optical properties

2021 ◽  
Author(s):  
Maria Ángeles Burgos Simón ◽  
Elisabeth Andrews ◽  
Gloria Titos ◽  
Angela Benedetti ◽  
Huisheng Bian ◽  
...  
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Relative Humidity ◽  
Water Uptake ◽  
Chem Phys ◽  
Earth System ◽  
Aerosol Optical Properties ◽  
System Models ◽  
Earth System Models

<p>The particle hygroscopic growth impacts the optical properties of aerosols and, in turn, affects the aerosol-radiation interaction and calculation of the Earth’s radiative balance. The dependence of particle light scattering on relative humidity (RH) can be described by the scattering enhancement factor f(RH), defined as the ratio between the particle light scattering coefficient at a given RH divided by its dry value.</p><p>The first effort of the AeroCom Phase III – INSITU experiment was to develop an observational dataset of scattering enhancement values at 26 sites to study the uptake of water by atmospheric aerosols, and evaluate f(RH) globally (Burgos et al., 2019). Model outputs from 10 Earth System Models (CAM, CAM-ATRAS, CAM-Oslo, GEOS-Chem, GEOS-GOCART, MERRAero, TM5, OsloCTM3, IFS-AER, and ECMWF) were then evaluated against this in-situ dataset. Building on these results, we investigate f(RH) in the context of other aerosol optical and chemical properties, making use of the same 10 Earth System Models (ESMs) and in-situ measurements as in Burgos et al. (2020) and Titos et al. (2021).</p><p>Given the difficulties of deploying and maintaining instrumentation for long-term, accurate and comprehensive f(RH) observations, it is desirable to find an observational proxy for f(RH). This observation-based proxy would also need to be reproduced in modelling space. Our aim here is to evaluate how ESMs currently represent the relationship between f(RH), scattering Ångström exponent (SAE), and single scattering albedo (SSA). This work helps to identify current challenges in modelling water-uptake by aerosols and their impact on aerosol optical properties within Earth system models.</p><p>We start by analyzing the behavior of SSA with RH, finding the expected increase with RH for all site types and models. Then, we analyze the three variables together (f(RH)-SSA-SAE relationship). Results show that hygroscopic particles tend to be bigger and scatter more than non-hygroscopic small particles, though variability within models is noticeable. This relationship can be further studied by relating SAE to model chemistry, by selecting those grid points dominated by a single chemical component (mass mixing ratios > 90%). Finally, we analyze model performance at three specific sites representing different aerosol types: Arctic, marine and rural. At these sites, the model data can be exactly temporally and spatially collocated with the observations, which should help to identify the models which exhibit better agreement with measurements and for which aerosol type.</p><p> </p><p>Burgos, M.A. et al.: A global view on the effect of water uptake on aerosol particle light scattering. Sci Data 6, 157. https://doi.org/10.1038/s41597-019-0158-7, 2019.</p><p>Burgos, M.A. et al.: A global model–measurement evaluation of particle light scattering coefficients at elevated relative humidity, Atmos. Chem. Phys., 20, 10231–10258, https://doi.org/10.5194/acp-20-10231-2020, 2020.</p><p>Titos, G. et al.: A global study of hygroscopicity-driven light scattering enhancement in the context of other in-situ aerosol optical properties, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2020-1250, in review, 2020.</p>

First global evaluation of the representation of water uptake within ten earth system models

2020 ◽  
Author(s):  
Maria Ángeles Burgos Simón ◽  
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Water Uptake ◽  
Phase Iii ◽  
Global Evaluation ◽  
Earth System ◽  
Aerosol Optical Properties ◽  
Large Variability ◽  
System Models ◽  
Earth System Models

<p>Aerosol optical properties, such as particle light scattering, depend on the particle size and chemical composition, which in turn are affected by the particle’s ability to take up water. Thus, particle hygroscopic growth will have an impact on the optical properties and in turn will affect the aerosol-radiation interaction and the calculations of the Earth’s radiative balance. The dependence of particle light scattering on relative humidity (RH) can be described by the scattering enhancement factor<em> f</em>(RH), defined as the ratio between the particle light scattering coefficient at a given RH divided by its dry value.</p><p>In our previous work (Burgos et al., 2019), we carried out a standardized analysis of scattering in-situ measurements at 26 sites around the globe, creating a benchmark dataset (open access via EBAS, http://ebas.nilu.no/). The project continues with the present work, which is part of the AeroCom phase III INSITU project: Evaluation of hygroscopicity of aerosol optical properties. Here, we present a comprehensive model-measurement evaluation of <em>f</em>(RH) for ten different earth system models. Modelled and measured scattering enhancement factors are compared for 22 sites, representative of Arctic, marine, rural, mountain, urban and desert aerosols.</p><p>Overall, a large variability and diversity in the magnitude of predicted <em>f</em>(RH) amongst the models is found and the modelled <em>f</em>(RH) tends to be overestimated relative to the measurement values. This difference cannot be explained by the aerosol type. Agreement between models and measurements was strongly influenced by the choice of RH<sub>ref</sub>. Models show a significantly larger discrepancy with the observations if model dry conditions are set to RH=0% instead of RH=40%. Model parameterizations of aerosol hygroscopicity and mixing state may be driving the observed diversity among models as well as the discrepancy with measurements. Measurement conditions have to be considered in this type of evaluation, specifically the fact that “dry” measurements may not be “dry” in model terms.</p><p>This work has been submitted to ACPD.</p><p>Burgos, M., Andrews, E., Titos, G., Alados-Arboledas, L., Baltensperger, U., Day, D., Jefferson, A., Kalivitis, N., Mihalopoulos, N., Sherman, J., Sun, J., Weingartner, E., and Zieger, P.: A global view on the effect of water uptake on aerosol particle light scattering, Scientific Data, 6, https://doi.org/10.1038/s41597-019-0158-7, 2019.</p>

scholarly journals Mass-based hygroscopicity parameter interaction model and measurement of atmospheric aerosol water uptake

2013 ◽  
Vol 13 (2) ◽  
pp. 717-740 ◽  
Author(s):  
E. Mikhailov ◽  
S. Vlasenko ◽  
D. Rose ◽  
U. Pöschl
Keyword(s):  
Water Vapor ◽  
Sodium Chloride ◽  
Ammonium Sulfate ◽  
Water Uptake ◽  
Malonic Acid ◽  
Atmospheric Aerosol ◽  
Interaction Model ◽  
Inorganic Particles ◽  
Vapor Supersaturation ◽  
Good Agreement

Abstract. In this study we derive and apply a mass-based hygroscopicity parameter interaction model for efficient description of concentration-dependent water uptake by atmospheric aerosol particles with complex chemical composition. The model approach builds on the single hygroscopicity parameter model of Petters and Kreidenweis (2007). We introduce an observable mass-based hygroscopicity parameter κm which can be deconvoluted into a dilute hygroscopicity parameter (κm0) and additional self- and cross-interaction parameters describing non-ideal solution behavior and concentration dependencies of single- and multi-component systems. For reference aerosol samples of sodium chloride and ammonium sulfate, the κm-interaction model (KIM) captures the experimentally observed concentration and humidity dependence of the hygroscopicity parameter and is in good agreement with an accurate reference model based on the Pitzer ion-interaction approach (Aerosol Inorganic Model, AIM). Experimental results for pure organic particles (malonic acid, levoglucosan) and for mixed organic-inorganic particles (malonic acid – ammonium sulfate) are also well reproduced by KIM, taking into account apparent or equilibrium solubilities for stepwise or gradual deliquescence and efflorescence transitions. The mixed organic-inorganic particles as well as atmospheric aerosol samples exhibit three distinctly different regimes of hygroscopicity: (I) a quasi-eutonic deliquescence & efflorescence regime at low-humidity where substances are just partly dissolved and exist also in a non-dissolved phase, (II) a gradual deliquescence & efflorescence regime at intermediate humidity where different solutes undergo gradual dissolution or solidification in the aqueous phase; and (III) a dilute regime at high humidity where the solutes are fully dissolved approaching their dilute hygroscopicity. For atmospheric aerosol samples collected from boreal rural air and from pristine tropical rainforest air (secondary organic aerosol) we present first mass-based measurements of water uptake over a wide range of relative humidity (1–99.4%) obtained with a new filter-based differential hygroscopicity analyzer (FDHA) technique. For these samples the concentration dependence of κm can be described by a simple KIM model equation based on observable mass growth factors and a total of only six fit parameters summarizing the combined effects of the dilute hygroscopicity parameters, self- and cross-interaction parameters, and solubilities of all involved chemical components. One of the fit parameters represents κm0 and can be used to predict critical dry diameters for the activation of cloud condensation nuclei (CCN) as a function of water vapor supersaturation according to Köhler theory. For sodium chloride and ammonium sulfate reference particles as well as for pristine rainforest aerosols consisting mostly of secondary organic matter, we obtained good agreement between the KIM predictions and measurement data of CCN activation. The application of KIM and mass-based measurement techniques shall help to bridge gaps in the current understanding of water uptake by atmospheric aerosols: (1) the gap between hygroscopicity parameters determined by hygroscopic growth measurements under sub-saturated conditions and by CCN activation measurements at water vapor supersaturation, and (2) the gap between the results of simplified single parameter models widely used in atmospheric or climate science and the results of complex multi-parameter ion- and molecule-interaction models frequently used in physical chemistry and solution thermodynamics (e.g., AIM, E-AIM, ADDEM, UNIFAC, AIOMFAC).

scholarly journals Aircraft profiles of aerosol microphysics and optical properties over North America: Aerosol optical depth and its association with PM2.5 and water uptake

2007 ◽  
Vol 112 (D12) ◽  
Author(s):  
Yohei Shinozuka ◽  
Antony D. Clarke ◽  
Steven G. Howell ◽  
Vladimir N. Kapustin ◽  
Cameron S. McNaughton ◽  
...  
Keyword(s):  
Optical Properties ◽  
North America ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Water Uptake

scholarly journals The role of organic aerosols in homogeneous ice formation

2004 ◽  
Vol 4 (5) ◽  
pp. 6719-6745
Author(s):  
B. Kärcher ◽  
T. Koop
Keyword(s):  
Sulfuric Acid ◽  
Water Uptake ◽  
Organic Aerosols ◽  
Supercooled Liquid ◽  
Accommodation Coefficient ◽  
Model Calculations ◽  
Inorganic Particles ◽  
Organic Particles ◽  
Homogeneous Freezing ◽  
Cooling Air

Abstract. Recent field observations suggest that the fraction of organics containing aerosol particles in ice cloud particles is diminished when compared to the background aerosol prior to freezing. In this work, we use model calculations to investigate possible causes for the observed behavior. In particular, homogeneous freezing processes in cooling air parcels containing aqueous inorganic particles (represented by sulfuric acid) and organic particles (represented by pure malonic acid and mixed malonic/sulfuric acid) are studied with a detailed microphysical model. A disparate water uptake and resulting size differences that occur between organic and inorganic particles prior to freezing are identified as the most likely reason for the poor partitioning of organic aerosols into the ice phase. The differences in water uptake can be caused by changes in the relationship between solute mass fraction and water activity of the supercooled liquid phase, by modifications of the accommodation coefficient for water molecules, or by a combination thereof. The behavior of peak ice saturation ratios and total ice crystal number concentrations is examined, and the dependence of the results on cooling rate is investigated. Finally, processes are discussed that could possibly modify the homogeneous freezing behavior of organic particles.

scholarly journals Optical Properties of Moderately-Absorbing Organic and Mixed Organic/Inorganic Particles at Very High Humidities

2012 ◽  
Author(s):  
Tami C Bond ◽  
Mark J Rood ◽  
Benjamin T Brem ◽  
Francisco C Mena-Gonzalez ◽  
Yanju Chen
Keyword(s):  
Optical Properties ◽  
Inorganic Particles ◽  
Very High

Papermaking Potential of Novel Structured PCC Fillers with Enhanced Refractive Index

TAPPI Journal ◽  
2010 ◽  
Vol 9 (1) ◽  
pp. 4-12 ◽  
Author(s):  
KIMMO KOIVUNEN ◽  
HANNU PAULAPURO
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Light Scattering ◽  
Particle Morphology ◽  
Strength Properties ◽  
Inorganic Particles ◽  
Refractive Index Contrast ◽  
Distribution Shape ◽  
Before And After ◽  
Index Contrast

While much effort has been focused on optical properties imparted by particle size distribution, shape, and packing of inorganic particles, the refractive index contrasts within the paper matrix have received less attention. PCC fillers can be used as tools for increasing the refractive index contrast, which further improves paper optical properties. We studied the papermaking potential of novel PCC fillers with an enhanced refractive index. PCC samples were fabricated by conventional carbonation method in the presence of refractive-index enhancing additives. We had previously found that introduction of ZnO as fine spots, including nano-sized structures, on host PCC surfaces improved the effective refractive index and optical performance of PCC. Now, we have studied the papermaking potential of this approach in experiments with handsheets using moderate Zn modification. In addition to Zn, we studied the effect of Sr as an additive and found that Sr inclusion alters the host particle morphology and crystal structure. We report effects of such modifications on light scattering coefficient, brightness, opacity, tensile strength, bulk, and porosity of paper, both before and after calendering. Our results suggest beneficial optical properties, as well as combination of light scattering with strength properties, especially in the case of Sr modified filler. Zn modified fillers opened the sheet structure, while Sr structuring closed the sheets. Calendering resulted in reduced bulk with all fillers, while optical properties were maintained with the Sr modified PCC, but reduced benefit was observed in the combination of light scattering and strength. Calendering conditions should therefore be optimized for these fillers. A higher modification degree of the fillers should also be considered to achieve a more significant refractive index contrast.

scholarly journals The role of organic aerosols in homogeneous ice formation

2005 ◽  
Vol 5 (3) ◽  
pp. 703-714 ◽  
Author(s):  
B. Kärcher ◽  
T. Koop
Keyword(s):  
Water Uptake ◽  
Organic Aerosols ◽  
Supercooled Liquid ◽  
Accommodation Coefficient ◽  
Model Calculations ◽  
Inorganic Particles ◽  
Ice Cloud ◽  
Organic Particles ◽  
Homogeneous Freezing ◽  
Cooling Air

Abstract. Recent field observations suggest that the fraction of organic-containing aerosol particles in ice cloud particles is diminished when compared to the background aerosol prior to freezing. In this work, we use model calculations to investigate possible causes for the observed behavior. In particular, homogeneous freezing processes in cooling air parcels containing aqueous inorganic particles and organic particles are studied with a detailed microphysical model. A disparate water uptake and resulting size differences that occur between organic and inorganic particles prior to freezing are identified as the most likely reason for the poor partitioning of organic aerosols into the ice phase. The differences in water uptake can be caused by changes in the relationship between solute mass fraction and water activity of the supercooled liquid phase, by modifications of the accommodation coefficient for water molecules, or by a combination thereof. The behavior of peak ice saturation ratios and total ice crystal number concentrations is examined, and the dependence of the results on cooling rate is investigated. Finally, processes are discussed that could possibly modify the homogeneous freezing behavior of organic particles.

scholarly journals Influence of particle-phase state on the hygroscopic behavior of mixed organic–inorganic aerosols

2015 ◽  
Vol 15 (9) ◽  
pp. 5027-5045 ◽  
Author(s):  
N. Hodas ◽  
A. Zuend ◽  
W. Mui ◽  
R. C. Flagan ◽  
J. H. Seinfeld
Keyword(s):  
Phase Behavior ◽  
Water Uptake ◽  
Indirect Evidence ◽  
Growth Curves ◽  
Radiative Properties ◽  
Particle Phase ◽  
Hygroscopic Growth ◽  
Inorganic Particles ◽  
Modeling Approaches ◽  
Simplified Modeling

Abstract. Recent work has demonstrated that organic and mixed organic–inorganic particles can exhibit multiple phase states depending on their chemical composition and on ambient conditions such as relative humidity (RH). To explore the extent to which water uptake varies with particle-phase behavior, hygroscopic growth factors (HGFs) of nine laboratory-generated, organic and organic–inorganic aerosol systems with physical states ranging from well-mixed liquids to phase-separated particles to viscous liquids or semi-solids were measured with the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe at RH values ranging from 40 to 90%. Water-uptake measurements were accompanied by HGF and RH-dependent thermodynamic equilibrium calculations using the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model. In addition, AIOMFAC-predicted growth curves are compared to several simplified HGF modeling approaches: (1) representing particles as ideal, well-mixed liquids; (2) forcing a single phase but accounting for non-ideal interactions through activity coefficient calculations; and (3) a Zdanovskii–Stokes–Robinson-like calculation in which complete separation of the inorganic and organic components is assumed at all RH values, with water uptake treated separately in each of the individual phases. We observed variability in the characteristics of measured hygroscopic growth curves across aerosol systems with differing phase behaviors, with growth curves approaching smoother, more continuous water uptake with decreasing prevalence of liquid–liquid phase separation and increasing oxygen : carbon ratios of the organic aerosol components. We also observed indirect evidence for the dehydration-induced formation of highly viscous semi-solid phases and for kinetic limitations to the crystallization of ammonium sulfate at low RH for sucrose-containing particles. AIOMFAC-predicted growth curves are generally in good agreement with the HGF measurements. The performances of the simplified modeling approaches, however, differ for particles with differing phase states. This suggests that no single simplified modeling approach can be used to capture the water-uptake behavior for the diversity of particle-phase behavior expected in the atmosphere. Errors in HGFs calculated with the simplified models are of sufficient magnitude to produce substantial errors in estimates of particle optical and radiative properties, particularly for the assumption that water uptake is driven by absorptive equilibrium partitioning with ideal particle-phase mixing.

Physical Properties of Poly(urethane-methacrylate)s Plastic Sheets Produced from Different Polyols

2009 ◽  
Vol 87-88 ◽  
pp. 481-486 ◽  
Author(s):  
Li Jun Gao ◽  
Li Ming Zhou ◽  
Shao Ming Fang ◽  
Hua Zheng ◽  
Min Hu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Optical Properties ◽  
Water Uptake ◽  
Mechanical Performance ◽  
Mechanical Analysis ◽  
Hydroxyethyl Methacrylate ◽  
Isophorone Diisocyanate ◽  
Performance Measurements ◽  
Optical Polymer

Poly (urethane-methacrylate) (PUA) plastic sheets were prepared from isophorone diisocyanate(IPDI), different kinds of polyols, and ß-hydroxyethyl methacrylate(HEMA) in the presence of dibutytin dilaurate(DBTL) as catalyst and 2,2-azo-bis-iso-butyro-nitrile(AIBN) as initiator. The properties of PUAs were measured by dynamic mechanical analysis (DMA), water uptake and optical properties testing, and mechanical performance measurements. The effect of kinds of polyols, which own the same molecular weight, on the properties of PUAs was evaluated. The results show the obtained PUAs present the good mechanical properties, low water uptake (below 2.5 %) and high transparence (above 85 %). The diversity of properties suggests that these PUAs can be used in optical polymer applications.

Sign in / Sign up

Export Citation Format

Share Document