Hygroscopic Growth of Multicomponent Aerosol Particles Influenced by Several Cycles of Relative Humidity

2008 ◽  
Vol 112 (11) ◽  
pp. 2378-2385 ◽  
Author(s):  
Thomas Rosenoern ◽  
Julie C. Schlenker ◽  
Scot T. Martin
Keyword(s):  
Relative Humidity ◽  
Aerosol Particles ◽  
Hygroscopic Growth

scholarly journals Effects of relative humidity on aerosol light scattering in the Arctic

2010 ◽  
Vol 10 (8) ◽  
pp. 3875-3890 ◽  
Author(s):  
P. Zieger ◽  
R. Fierz-Schmidhauser ◽  
M. Gysel ◽  
J. Ström ◽  
S. Henne ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Light Scattering ◽  
Relative Humidity ◽  
Aerosol Particles ◽  
Aerosol Size Distribution ◽  
Hygroscopic Growth ◽  
Scattering Coefficients ◽  
Dry Conditions ◽  
Hygroscopic Particles

Abstract. Aerosol particles experience hygroscopic growth in the ambient atmosphere. Their optical properties – especially the aerosol light scattering – are therefore strongly dependent on the ambient relative humidity (RH). In-situ light scattering measurements of long-term observations are usually performed under dry conditions (RH>30–40%). The knowledge of this RH effect is of eminent importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. This study combines measurements and model calculations to describe the RH effect on aerosol light scattering for the first time for aerosol particles present in summer and fall in the high Arctic. For this purpose, a field campaign was carried out from July to October 2008 at the Zeppelin station in Ny-Ålesund, Svalbard. The aerosol light scattering coefficient σsp(λ) was measured at three distinct wavelengths (λ=450, 550, and 700 nm) at dry and at various, predefined RH conditions between 20% and 95% with a recently developed humidified nephelometer (WetNeph) and with a second nephelometer measuring at dry conditions with an average RH<10% (DryNeph). In addition, the aerosol size distribution and the aerosol absorption coefficient were measured. The scattering enhancement factor f(RH, λ) is the key parameter to describe the RH effect on σsp(λ) and is defined as the RH dependent σsp(RH, λ) divided by the corresponding dry σsp(RHdry, λ). During our campaign the average f(RH=85%, λ=550 nm) was 3.24±0.63 (mean ± standard deviation), and no clear wavelength dependence of f(RH, λ) was observed. This means that the ambient scattering coefficients at RH=85% were on average about three times higher than the dry measured in-situ scattering coefficients. The RH dependency of the recorded f(RH, λ) can be well described by an empirical one-parameter equation. We used a simplified method to retrieve an apparent hygroscopic growth factor g(RH), defined as the aerosol particle diameter at a certain RH divided by the dry diameter, using the WetNeph, the DryNeph, the aerosol size distribution measurements and Mie theory. With this approach we found, on average, g(RH=85%) values to be 1.61±0.12 (mean±standard deviation). No clear seasonal shift of f(RH, λ) was observed during the 3-month period, while aerosol properties (size and chemical composition) clearly changed with time. While the beginning of the campaign was mainly characterized by smaller and less hygroscopic particles, the end was dominated by larger and more hygroscopic particles. This suggests that compensating effects of hygroscopicity and size determined the temporal stability of f(RH, λ). During sea salt influenced periods, distinct deliquescence transitions were observed. At the end we present a method on how to transfer the dry in-situ measured aerosol scattering coefficients to ambient values for the aerosol measured during summer and fall at this location.

scholarly journals Effect of mixing structure on the water uptake of mixtures of ammonium sulfate and phthalic acid particles

2021 ◽  
Vol 21 (3) ◽  
pp. 2179-2190
Author(s):  
Weigang Wang ◽  
Ting Lei ◽  
Andreas Zuend ◽  
Hang Su ◽  
Yafang Cheng ◽  
...  
Keyword(s):  
Growth Factor ◽  
Relative Humidity ◽  
Water Uptake ◽  
Phthalic Acid ◽  
Aerosol Particles ◽  
Core Shell ◽  
Hygroscopic Growth ◽  
The Core ◽  
Mass Fractions ◽  
Mixing States

Abstract. Aerosol mixing state regulates the interactions between water molecules and particles and thus controls aerosol activation and hygroscopic growth, which thereby influences visibility degradation, cloud formation, and its radiative forcing. There are, however, few current studies on the mixing structure effects on aerosol hygroscopicity. Here, we investigated the hygroscopicity of ammonium sulfate / phthalic acid (AS / PA) aerosol particles with different mass fractions of PA in different mixing states in terms of initial particle generation. Firstly, the effect of PA coatings on the hygroscopic behavior of the core-shell-generated mixtures of AS with PA was studied using a coating hygroscopicity tandem differential mobility analyzer (coating HTDMA). The slow increase in the hygroscopic growth factor of core-shell-generated particles is observed with increasing thickness of the coating PA prior to the deliquescence relative humidity (DRH) of AS. At relative humidity (RH) above 80 %, a decrease in the hygroscopic growth factor of particles occurs as the thickness of the PA shell increases, which indicates that the increase of PA mass fractions leads to a reduction of the overall core-shell-generated particle hygroscopicity. In addition, the use of the Zdanovskii–Stokes–Robinson (ZSR) relation leads to the underestimation of the measured growth factors of core-shell-generated particles without consideration of the morphological effect of core-shell-generated particles, especially at higher RH. Secondly, in the case of the AS / PA initially well-mixed particles, a shift of the DRH of AS (∼80 %, Tang and Munkelwitz, 1994) to lower RH is observed due to the presence of PA in the initially well-mixed particles. The predicted hygroscopic growth factor using the ZSR relation is consistent with the measured hygroscopic growth factor of the initially well-mixed particles. Moreover, we compared and discussed the influence of mixing states on the water uptake of AS / PA aerosol particles. It is found that the hygroscopic growth factor of the core-shell-generated particles is slightly higher than that of the initially well-mixed particles with the same mass fractions of PA at RH above 80 %. The observation of AS / PA particles may contribute to a growing field of knowledge regarding the influence of coating properties and mixing structure on water uptake.

scholarly journals Hygroscopic properties of aerosol particles at high relative humidity and their diurnal variations in the North China Plain

2011 ◽  
Vol 11 (7) ◽  
pp. 3479-3494 ◽  
Author(s):  
P. F. Liu ◽  
C. S. Zhao ◽  
T. Göbel ◽  
E. Hallbauer ◽  
A. Nowak ◽  
...  
Keyword(s):  
Relative Humidity ◽  
North China Plain ◽  
North China ◽  
Aerosol Particles ◽  
Diurnal Variations ◽  
Hygroscopic Growth ◽  
Carbonaceous Particles ◽  
The North ◽  
Hygroscopic Properties ◽  
The North China Plain

Abstract. The hygroscopic properties of submicron aerosol particles were determined at a suburban site (Wuqing) in the North China Plain among a cluster of cities during the period 17 July to 12 August, 2009. A High Humidity Tandem Differential Mobility Analyser (HH-TDMA) instrument was applied to measure the hygroscopic growth factor (GF) at 90%, 95% and 98.5% relative humidity (RH) for particles with dry diameters between 50 and 250 nm. The probability distribution of GF (GF-PDF) averaged over the period shows a distinct bimodal pattern, namely, a dominant more-hygroscopic (MH) group and a smaller nearly-hydrophobic (NH) group. The MH group particles were highly hygroscopic, and their GF was relatively constant during the period with average values of 1.54 ± 0.02, 1.81 ± 0.04 and 2.45 ± 0.07 at 90%, 95% and 98.5% RH (D0 = 100 nm), respectively. The NH group particles grew very slightly when exposed to high RH, with GF values of 1.08 ± 0.02, 1.13 ± 0.06 and 1.24 ± 0.13 respectively at 90%, 95% and 98.5% RH (D0 = 100 nm). The hygroscopic growth behaviours at different RHs were well represented by a single-parameter Köhler model. Thus, the calculation of GF as a function of RH and dry diameter could be facilitated by an empirical parameterization of κ as function of dry diameter. A strong diurnal pattern in number fraction of different hygroscopic groups was observed. The average number fraction of NH particles during the day was about 8%, while during the nighttime fractions up to 20% were reached. Correspondingly, the state of mixing in terms of water uptake varied significantly during a day. Simulations using a particle-resolved aerosol box model (PartMC-MOSAIC) suggest that the diurnal variations of aerosol hygroscopicity and mixing state were mainly caused by the evolution of the atmospheric mixing layer. The shallow nocturnal boundary layer during the night facilitated the accumulation of freshly emitted carbonaceous particles (mainly hydrophobic) near the surface while in the morning turbulence entrained the more aged and more hygroscopic particles from aloft and diluted the NH particles near the surface resulting in a decrease in the fraction of NH particles.

scholarly journals Effects of relative humidity on aerosol light scattering in the Arctic

2010 ◽  
Vol 10 (2) ◽  
pp. 3659-3698 ◽  
Author(s):  
P. Zieger ◽  
R. Fierz-Schmidhauser ◽  
M. Gysel ◽  
J. Ström ◽  
S. Henne ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Light Scattering ◽  
Relative Humidity ◽  
Aerosol Particles ◽  
Aerosol Size Distribution ◽  
Hygroscopic Growth ◽  
Scattering Coefficients ◽  
Dry Conditions ◽  
Hygroscopic Particles

Abstract. Aerosol particles experience hygroscopic growth in the ambient atmosphere. Their optical properties – especially the aerosol light scattering – are therefore strongly dependent on the ambient relative humidity (RH). In-situ light scattering measurements of long-term observations are usually performed under dry conditions (RH<30–40%). The knowledge of this RH effect is of eminent importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. This study combines measurements and model calculations to describe the RH effect on aerosol light scattering for the first time of aerosol particles present in summer and fall at the high Arctic. For this purpose, a field campaign was carried out from July to October 2008 at the Zeppelin station in Ny-Ålesund, Svalbard. The aerosol light scattering coefficient σsp(λ) was measured at three distinct wavelengths (λ=450, 550, and 700 nm) at dry and at various, predefined RH conditions between 20% and 95% with a recently developed humidified nephelometer (WetNeph) and with a second nephelometer measuring at dry conditions (DryNeph). In addition, the aerosol size distribution and the aerosol absorption coefficient were measured. The scattering enhancement factor f(RH,λ) is the key parameter to describe the RH effect on σsp(λ) and is defined as the RH dependent σsp(RH,λ) divided by the corresponding dry σsp(RHdry,λ). During our campaign the average f(RH=85%, λ=550 nm) was 3.24±0.63 (mean ± standard deviation), and no clear wavelength dependence of f(RH,λ) was observed. This means that the ambient scattering coefficients at RH=85% were on average about three times higher than the dry measured in-situ scattering coefficients. The RH dependency of the recorded f(RH,λ) can be well described by an empirical one-parameter equation. We used a simplified method to retrieve an apparent hygroscopic growth factor g, defined as the aerosol particle diameter at a certain RH divided by the dry diameter, using the WetNeph, the DryNeph, the aerosol size distribution measurements and Mie theory. With this approach we found on average for g values of 1.61±0.12 (mean ± standard deviation). No clear seasonal shift of f(RH,λ) was observed during the 3-month period, while aerosol properties (size and chemical composition) clearly changed with time. While the beginning of the campaign was mainly characterized by smaller and less hygroscopic particles, the end was dominated by larger and more hygroscopic particles. This suggests that compensating effects of hygroscopicity and size determined the temporal stability of f(RH,λ). During sea salt influenced periods, distinct deliquescence transitions were observed. At the end we give a method on how to transfer the dry in-situ measured aerosol scattering coefficients to ambient values for the aerosol measured during summer and fall at this location.

scholarly journals Amorphous and crystalline aerosol particles interacting with water vapor: conceptual framework and experimental evidence for restructuring, phase transitions and kinetic limitations

2009 ◽  
Vol 9 (24) ◽  
pp. 9491-9522 ◽  
Author(s):  
E. Mikhailov ◽  
S. Vlasenko ◽  
S. T. Martin ◽  
T. Koop ◽  
U. Pöschl
Keyword(s):  
Phase Transitions ◽  
Water Vapor ◽  
Relative Humidity ◽  
Atmospheric Aerosols ◽  
Aerosol Particles ◽  
Organic Substances ◽  
Hygroscopic Growth ◽  
Amorphous Phases ◽  
Semi Solid ◽  
Hydration And Dehydration

Abstract. Interactions with water are crucial for the properties, transformation and climate effects of atmospheric aerosols. Here we present a conceptual framework for the interaction of amorphous aerosol particles with water vapor, outlining characteristic features and differences in comparison to crystalline particles. We used a hygroscopicity tandem differential mobility analyzer (H-TDMA) to characterize the hydration and dehydration of crystalline ammonium sulfate, amorphous oxalic acid and amorphous levoglucosan particles (diameter ~100 nm, relative humidity 5–95% at 298 K). The experimental data and accompanying Köhler model calculations provide new insights into particle microstructure, surface adsorption, bulk absorption, phase transitions and hygroscopic growth. The results of these and related investigations lead to the following conclusions: (1) Many organic substances, including carboxylic acids, carbohydrates and proteins, tend to form amorphous rather than crystalline phases upon drying of aqueous solution droplets. Depending on viscosity and microstructure, the amorphous phases can be classified as glasses, rubbers, gels or viscous liquids. (2) Amorphous organic substances tend to absorb water vapor and undergo gradual deliquescence and hygroscopic growth at lower relative humidity than their crystalline counterparts. (3) In the course of hydration and dehydration, certain organic substances can form rubber- or gel-like structures (supramolecular networks) and undergo transitions between swollen and collapsed network structures. (4) Organic gels or (semi-)solid amorphous shells (glassy, rubbery, ultra-viscous) with low molecular diffusivity can kinetically limit the uptake and release of water and may influence the hygroscopic growth and activation of aerosol particles as cloud condensation nuclei (CCN) and ice nuclei (IN). Moreover, (semi-)solid amorphous phases may influence the uptake of gaseous photo-oxidants and the chemical transformation and aging of atmospheric aerosols. (5) The shape and porosity of amorphous and crystalline particles formed upon dehydration of aqueous solution droplets depend on chemical composition and drying conditions. The apparent volume void fractions of particles with highly porous structures can range up to ~50% or more (xerogels, aerogels). (6) For efficient description of water uptake and phase transitions of aerosol particles, we propose not to limit the terms deliquescence and efflorescence to equilibrium phase transitions of crystalline substances. Instead we propose generalized definitions according to which amorphous and crystalline components can undergo gradual or prompt, partial or full deliquescence or efflorescence. We suggest that (semi-)solid amorphous phases may be important not only in the upper atmosphere as suggested in recent studies of glass formation at low temperatures. Depending on relative humidity, (semi-)solid phases and moisture-induced glass transitions may also play a role in gas-particle interactions at ambient temperatures in the lower atmosphere.

scholarly journals High-humidity tandem differential mobility analyzer for accurate determination of aerosol hygroscopic growth, microstructure, and activity coefficients over a wide range of relative humidity

2020 ◽  
Vol 13 (4) ◽  
pp. 2035-2056 ◽  
Author(s):  
Eugene F. Mikhailov ◽  
Sergey S. Vlasenko
Keyword(s):  
Growth Factors ◽  
Relative Humidity ◽  
Activity Coefficients ◽  
Aerosol Particles ◽  
Accurate Determination ◽  
High Humidity ◽  
Optimal Parameters ◽  
Hygroscopic Growth ◽  
Average Deviation ◽  
Wide Range

Abstract. Interactions with water are crucial for the properties, transformation, and climate effects of atmospheric aerosols. Here we present the high-humidity tandem differential hygroscopicity analyzer (HHTDMA) and a new method to measure the hygroscopic growth of aerosol particles with in situ restructuring to minimize the influence of particle shape. With this approach, growth factors can be measured with an uncertainty of 0.3 %–0.9 % over a relative humidity (RH) range of 2 %–99.6 % and with an RH measurement accuracy better than 0.4 %. The HHTDMA instrument can be used in hydration, dehydration, and restructuring modes of operation. The restructuring mode allows us to investigate the effects of drying conditions on the initial microstructure of aerosol particles and specifies the optimal parameters that provide their rearrangements into compact structures with a nearly spherical shape. These optimal parameters were used in hygroscopic growth experiments by combining the restructuring mode with a conventional hydration or dehydration mode. The tandem of two modes allowed us to measure the particle growth factors with high precision as well as to determine the thickness of the water adsorption layer on the surface of compact crystalline particles. To verify the HHTDMA instrument we compared the measured ammonium sulfate growth factors with those obtained from the E-AIM-based Köhler model (E-AIM: Extended Aerosol Inorganics Model). Averaged over the range of 38 %–96 % RH, the mean relative deviations between measurements and model results is less than 0.5 %. We demonstrate this precision by presenting data for glucose, for which bulk thermodynamic coefficients are available. The HHTDMA-derived activity coefficients of water and glucose were obtained for both dilute and supersaturated solutions and are in good agreement with those reported in the literature. The average deviation between the measured activity coefficients and those obtained by the bulk method is less than 4 %. For dilute solution in water with an activity range of 0.98–0.99, the hygroscopicity parameter of glucose and the molal osmotic coefficient were obtained with an uncertainty of 0.4 % and 2.5 %, respectively.

scholarly journals High humidity tandem differential mobility analyzer for accurate determination of aerosol hygroscopic growth, microstructure and activity coefficients over a wide range of relative humidity

2019 ◽  
Author(s):  
Eugene F. Mikhailov ◽  
Sergey S. Vlasenko
Keyword(s):  
Growth Factors ◽  
Relative Humidity ◽  
Activity Coefficients ◽  
Aerosol Particles ◽  
Accurate Determination ◽  
Spherical Shape ◽  
High Humidity ◽  
Optimal Parameters ◽  
Hygroscopic Growth ◽  
Wide Range

Abstract. Interactions with water are crucial for the properties, transformation and climate effects of atmospheric aerosols. Here we present high humidity tandem differential hygroscopicity analyzer (HHTDMA) and a new method to measure the hygroscopic growth of aerosol particles with in-situ restructuring to minimize the influence of particle shape. With this approach, growth factors can be measured with an uncertainty 0.3–0.9 % over a relative humidity (RH) range of 2–99.6 % and with an RH measurement accuracy better than 0.4 %. The HHTDMA instrument can be used in hydration, dehydration and restructuring modes of operation. The restructuring mode allows to investigate the effects of drying conditions on the initial microstructure of aerosol particles and specified the optimal parameters that provide their rearrangements into compact structures with near-spherical shape. These optimal parameters were then used in hygroscopic growth experiments by combining restructuring mode with conventional hydration or dehydration mode. The tandem of two modes allowed us to measure the particle growth factors with high precision as well as to determine the thickness of the water adsorption layer on the surface of compact crystalline particles. To verify HHTDMA instrument we compared the measured ammonium sulfate growth factors with these obtained from E-AIM-based Köhler model. Averaged over the range of 38–96 % RH, the mean relative deviations between measurement and model results is less than 0.5 %. We demonstrate this precision by presenting data for glucose for which bulk thermodynamic coefficients are available. The HHTDMA-derived activity coefficients of water and glucose were obtained for both dilute and supersaturated solutions and are in a good agreement with these reported in literature. Averaged deviation between the measured activity coefficients and these obtained by bulk method is less than 4 %. For dilute solution in water activity range of 0.98–0.99 the hygroscopicity parameter of glucose and molal osmotic coefficient were obtained with uncertainty of 0.4 % and 2.5 %, respectively.

scholarly journals Hygroscopic properties of aerosol particles at high relative humidity and their diurnal variations in the North China Plain

2011 ◽  
Vol 11 (1) ◽  
pp. 2991-3040 ◽  
Author(s):  
P. F. Liu ◽  
C. S. Zhao ◽  
T. Göbel ◽  
E. Hallbauer ◽  
A. Nowak ◽  
...  
Keyword(s):  
Relative Humidity ◽  
North China Plain ◽  
North China ◽  
Aerosol Particles ◽  
Diurnal Variations ◽  
Hygroscopic Growth ◽  
Mixing State ◽  
The North ◽  
Hygroscopic Properties ◽  
The North China Plain

Abstract. The hygroscopic properties of submicron aerosol particles were determined at a suburban site (Wuqing) in the North China Plain among a cluster of cities during the period 17 July to 12 August 2009. A High Humidity Tandem Differential Mobility Analyser (HH-TDMA) instrument was applied to measure the hygroscopic growth factor (GF) at 90%, 95% and 98.5% relative humidity (RH) for particles with dry diameter between 50–250 nm. The probability distribution of GF (GF-PDF) averaged over the period shows a distinct bimodal pattern, namely, a dominant more-hygroscopic (MH) group and a smaller nearly-hydrophobic (NH) group. The MH group particles were highly hygroscopic, and their GF was relatively constant during the period with average values of 1.54±0.02, 1.81±0.04 and 2.45±0.07 at 90%, 95% and 98.5% RH (D0=100 nm), respectively. The NH group particles grew very slightly when exposed to high RH, with GF values of 1.08±0.02, 1.13±0.06 and 1.24±0.13, respectively at 90%, 95% and 98.5% RH (D0=100 nm). The hygroscopic growth behaviours at different RHs were well represented by the hygroscopicity parameter κ with a single-parameter Köhler model. Thus, the calculation of GF as a function of RH and dry diameter could be facilitated by an empirical parameterization of κ as function of dry diameter. A strong diurnal pattern in number fraction of different hygroscopic groups was observed, indicating a diurnal variation of aerosol mixing state and/or chemical composition. The average number fraction of NH particles during the day was about 8%, while during the nighttime fractions up to 20% were reached. Correspondingly, the state of mixing in terms of water uptake varied significantly during a day. The high fraction of NH particles measured during the night denotes a high degree of external mixing of ambient aerosols, while during the day the degree of external mixing decreased. Simulations using a particle-resolved aerosol box model (PartMC-MOSAIC) suggest that the diurnal variations of aerosol hygroscopicity and mixing state were mainly caused by the evolution of the atmospheric mixing layer. The shallow nocturnal boundary layer during the night facilitated the accumulation of freshly emitted carbonaceous particles (mainly hydrophobic) near the surface while in the morning turbulence entrained the more aged and more hygroscopic particles from aloft and diluted the NH particles near the surface resulting in a decrease in the fraction of NH particles.

Sign in / Sign up

Export Citation Format

Share Document