scholarly journals Aerosol hygroscopicity at Ispra EMEP-GAW station

2012 ◽  
Vol 12 (2) ◽  
pp. 5293-5340 ◽  
Author(s):  
M. Adam ◽  
J. P. Putaud ◽  
S. Martins dos Santos ◽  
A. Dell'Acqua ◽  
C. Gruening
Keyword(s):  
Growth Factor ◽  
Relative Humidity ◽  
Mie Theory ◽  
Data Consistency ◽  
Absorption Enhancement ◽  
Hygroscopic Growth ◽  
Extinction Coefficients ◽  
Aerosol Absorption ◽  
Hygroscopic Properties ◽  
Enhancement Factors

Abstract. This study focuses on the aerosol hygroscopic properties as determined from ground-based measurements and Mie theory. Usually, aerosol ground-based measurements are taken in dry conditions to ensure data consistency within networks. The dependence of the various aerosol optical characteristics (e.g. aerosol absorption, scattering, backscattering or extinction coefficients) on relative humidity has therefore to be established in order to determine their values in the atmosphere, where relative humidity can reach high values. We calculated mean monthly diurnal values of the aerosol hygroscopic growth factor at 90% relative humidity GF(90) based on measurements performed at EMEP-GAW station of Ispra with a Hygroscopicity Tandem Differential Mobility Analyzer over eight months in 2008 and 2009. Particle hygroscopicity increases with particle dry diameter ranging from 35 to 165 nm for all seasons. We observed a clear seasonal variation in GF(90) for particles larger than 75 nm, and a diurnal cycle in spring and winter for all sizes. For 165 nm particles, GF(90) averages 1.32 ± 0.06. The effect of the particle hygroscopic growth on the aerosol optical properties (scattering, extinction, absorption and backscatter coefficients, asymmetry parameter and backscatter faction) was computed using the Mie theory, based on data obtained from a series of instruments running at our station. We found median enhancement factors (defined as ratios between the values of optical variables at 90% and 0% relative humidity) equal to 1.1, 2.1, 1.7, and 1.8, for the aerosol absorption, scattering, backscattering, and extinction coefficients, respectively. All except the absorption enhancement factor show a strong correlation with the hygroscopic growth factor. The enhancement factors observed at our site are among the lowest observed across the world for the aerosol scattering coefficient, and among the highest for the aerosol backscatter fraction.

scholarly journals Aerosol hygroscopicity at a regional background site (Ispra) in Northern Italy

2012 ◽  
Vol 12 (13) ◽  
pp. 5703-5717 ◽  
Author(s):  
M. Adam ◽  
J. P. Putaud ◽  
S. Martins dos Santos ◽  
A. Dell'Acqua ◽  
C. Gruening
Keyword(s):  
Growth Factor ◽  
Relative Humidity ◽  
Mie Theory ◽  
Absorption Enhancement ◽  
Research Station ◽  
Hygroscopic Growth ◽  
Extinction Coefficients ◽  
Aerosol Absorption ◽  
Hygroscopic Properties ◽  
Enhancement Factors

Abstract. This study focuses on the aerosol hygroscopic properties as determined from ground-based measurements and Mie theory. Usually, aerosol ground-based measurements are taken in dry conditions in order to have a consistency within networks. The dependence of the various aerosol optical characteristics (e.g. aerosol absorption, scattering, backscattering or extinction coefficients) on relative humidity has therefore to be established in order to determine their values in the atmosphere, where relative humidity can reach high values. We calculated mean monthly diurnal values of the aerosol hygroscopic growth factor at 90% relative humidity GF(90) based on measurements performed at the atmospheric research station in Ispra (Italy) with a Hygroscopicity Tandem Differential Mobility Analyzer over eight months in 2008 and 2009. Particle hygroscopicity increases with particle dry diameter ranging from 35 to 165 nm for all seasons. We observed a clear seasonal variation in GF(90) for particles larger than 75 nm, and a diurnal cycle in spring and winter for all sizes. For 165 nm particles, GF(90) averages 1.32 ± 0.06. The effect of the particle hygroscopic growth on the aerosol optical properties (scattering, extinction, absorption and backscatter coefficients, asymmetry parameter and backscatter faction) was computed using the Mie theory, based on data obtained from a series of instruments running at our station. We found median enhancement factors (defined as ratios between the values of optical variables at 90% and 0% relative humidity) equal to 1.1, 2.1, 1.7, and 1.8, for the aerosol absorption, scattering, backscattering, and extinction coefficients, respectively. All except the absorption enhancement factors show a strong correlation with the hygroscopic growth factor. The enhancement factors observed at our site are among the lowest observed across the world for the aerosol scattering coefficient, and among the highest for the aerosol backscatter fraction.

scholarly journals Quantifying the hygroscopic properties of cyclodextrin containing aerosol for drug delivery to the lungs

2020 ◽  
Vol 22 (20) ◽  
pp. 11327-11336
Author(s):  
C. P. F. Day ◽  
A. Miloserdov ◽  
K. Wildish-Jones ◽  
E. Pearson ◽  
A. E. Carruthers
Keyword(s):  
Drug Delivery ◽  
Growth Factor ◽  
Hygroscopic Growth ◽  
Vapour Sorption ◽  
Hygroscopic Properties ◽  
Dynamic Vapour Sorption

The hygroscopic growth factor for individual aqueous 2-hydroxypropyl β-cyclodextrin droplets has been measured and compared with dynamic vapour sorption measurements.

Reconstructed expression for aerosol extinction coefficient by considering mass extinction efficiency and hygroscopic growth for polydipersed aerosol

2020 ◽  
Author(s):  
Chang Hoon Jung ◽  
JiYi Lee ◽  
Junshik Um ◽  
Yong Pyo Kim
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Growth Factor ◽  
Size Distribution ◽  
Enhancement Factor ◽  
Size Range ◽  
Geometric Mean ◽  
Mie Theory ◽  
Hygroscopic Growth ◽  
Particle Size Range

<p>In this study, simplified analytic type of expression for size dependent MEs (Mass efficiencies) are developed. The entire size was considered assuming lognormal size distribution for sulfate, nitrate and NaCl aerosol species and the MEE of each aerosol chemical composition was estimated by fitting Mie’s calculation. The obtained results are compared with the results from the Mie-theory-based calculations and showed comparable results.</p><p>The mass efficiencies of all aerosol components for each size range are compared with Mie’s results and approximated as a function of geometric mean diameter in the form of a power law formula. Finally, harmonic mean type approximation was used to cover entire particle size range.</p><p>Also, analytic expression of approximated scattering enhancement factor which stands for the effect of hygroscopic growth factor for polydispersed aerosol on aerosol optical properties are obtained.</p><p>Based on aerosol thermodynamic models, mass growth factor can be obtained and their optical properties can be obtained by using Mie theory with different aerosol properties and size distribution. Finally, scattering enhancement factor was approximated fRH for polydispersed aerosol as a function of RH.</p><p>Finally, we also compared the simple forcing efficiency (SFE, W/g) of polydisperse aerosols between the developed simple approach and by the method using the Mie theory. The results show that current obtained approximated methods are comparable with existing numercal calculation based results for polydipersed particle size.</p>

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 newly formed ultrafine particles at an urban site surrounded by deciduous forest (Sapporo, northern Japan) during the summer of 2011

2014 ◽  
Vol 14 (14) ◽  
pp. 7519-7531 ◽  
Author(s):  
J. Jung ◽  
K. Kawamura
Keyword(s):  
Growth Factor ◽  
Ultrafine Particles ◽  
Deciduous Forest ◽  
Urban Site ◽  
Hygroscopic Growth ◽  
Organic Vapors ◽  
Nucleation Mode ◽  
Hygroscopic Properties ◽  
Aitken Mode ◽  
Northern Japan

Abstract. To investigate the hygroscopic properties of ultrafine particles during new particle formation events, the hygroscopic growth factors of size-segregated atmospheric particles were measured at an urban site in Sapporo, northern Japan, during the summer of 2011. The hygroscopic growth factor at 85 % relative humidity [g(85%)] of freshly formed nucleation mode particles was 1.11 to 1.28 (average: 1.16 ± 0.06) at a dry particle diameter (Dp) centered on 20 nm, which is equivalent to 1.17 to 1.35 (1.23 ± 0.06) at a dry Dp centered on 100 nm after considering the Kelvin effect. These values are comparable with those of secondary organic aerosols, suggesting that low-volatility organic vapors are important to the burst of nucleation mode particles. The equivalent g(85%) at a dry Dp of 100 nm for nucleated particles that have grown to Aitken mode sizes (1.24 to 1.34; average: 1.30 ± 0.04) were slightly higher than those of newly formed nucleation mode particles, suggesting that the growth of freshly formed nucleation mode particles to the Aitken mode size can be subjected to condensation of not only low-volatility organic vapors, but also water-soluble inorganic species. Based on this result, and previous measurement of radiocarbon in aerosols, we suggest that the burst of nucleation mode particles and their subsequent growth were highly affected by biogenic organic emissions at this measurement site, which is surrounded by deciduous forest. Gradual increases in mode diameter after the burst of nucleation mode particles were observed under southerly wind conditions, with a dominant contribution of intermediately hygroscopic particles. However, sharp increases in mode diameter were observed when the wind direction shifted to northwesterly or northeasterly, with a sharp increase in the highly hygroscopic particle fraction of the Aitken mode particles, indicating that the hygroscopic growth factor of newly formed particles is perturbed by the local winds that deliver different air masses to the measurement site.

scholarly journals Design and Application of an Unattended Multifunctional H-TDMA System

2013 ◽  
Vol 30 (6) ◽  
pp. 1136-1148 ◽  
Author(s):  
Haobo Tan ◽  
Hanbing Xu ◽  
Qilin Wan ◽  
Fei Li ◽  
Xuejiao Deng ◽  
...  
Keyword(s):  
Particle Size ◽  
Growth Factor ◽  
Cloud Condensation Nuclei ◽  
Polystyrene Latex ◽  
Hygroscopic Growth ◽  
Differential Mobility Analyzer ◽  
Differential Mobility ◽  
China Meteorological Administration ◽  
Hygroscopic Properties ◽  
Calibration Methods

Abstract The hygroscopic properties of aerosols have a significant impact on aerosol particle number size distributions (PNSD), formation of cloud condensation nuclei, climate forcing, and atmospheric visibility, as well as human health. To allow for the observation of the hygroscopic growth of aerosols with long-term accuracy, an unattended multifunctional hygroscopicity-tandem differential mobility analyzer (H-TDMA) system was designed and built by the Institute of Tropical and Marine Meteorology (ITMM), China Meteorological Administration (CMA), in Guangzhou, China. The system is capable of measuring dry and wet PNSD, hygroscopic growth factor by particle size, and mixing states. This article describes in detail the working principles, components, and calibration methods of the system. Standard polystyrene latex (PSL) spheres with five different diameters were chosen to test the system’s precision and accuracy of particle size measurement. Ammonium sulfate was used to test the hygroscopic response of the system for accurate growth factor measurement. The test results show that the deviation of the growth factor measured by the system is within a scope of −0.01 to −0.03 compared to Köhler theoretical curves. Results of temperature and humidity control performance tests indicate that the system is robust. An internal temperature gradient of less than 0.2 K for a second differential mobility analyzer (DMA2) makes it possible to reach a set-point relative humidity (RH) value of 90% and with a standard deviation of ±0.44%, sufficient for unattended field observation.

scholarly journals Hygroscopic properties and mixing state of aerosol measured at the high altitude site Puy de Dôme (1465 m a.s.l.), France

2014 ◽  
Vol 14 (5) ◽  
pp. 6759-6802
Author(s):  
H. Holmgren ◽  
K. Sellegri ◽  
M. Hervo ◽  
C. Rose ◽  
E. Freney ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Particle Size ◽  
Growth Factor ◽  
High Altitude ◽  
Hygroscopic Growth ◽  
Mixing State ◽  
Air Mass ◽  
Hygroscopic Properties ◽  
Seasonal And Diurnal Variations ◽  
Mass Type

Abstract. A Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) was used to evaluate the hygroscopic properties of aerosol particles measured at the Puy de Dôme research station in central France from September 2008 to December 2012. This high-altitude site is ideally situated to allow for both the upper part of the planetary boundary layer and the lower free troposphere to be sampled. The aim of the study is to investigate both the influence of year-to-year, seasonal, and diurnal cycles, as well as the influence of air mass type on particle hygroscopicity and mixing state. Results show that particle hygroscopicity increases with particle size and depends both on air mass type and on season. Average growth factor values are lowest in winter (1.21 ± 0.13, 1.23 ± 0.18 and 1.38 ± 0.25 for 25, 50 and 165 nm particles, respectively) and highest in autumn (1.27 ± 0.11, 1.32 ± 0.12 and 1.49 ± 0.15 for 25, 50 and 165 nm particles, respectively). Particles are generally more hygroscopic at night than during the day. The seasonal and diurnal variations are likely to be strongly influenced by boundary layer dynamics. Furthermore, particles originating from oceanic and continental regions tend to be more hygroscopic than those measured in African and local air masses. The high hygroscopicity of marine aerosol may be explained by large proportions of inorganic aerosol and sea salts, and it is speculated that continental particles are more hygroscopic than local and African ones due to ageing of fresh combustion aerosol. Aerosol measured at the Puy de Dôme display a high degree of external mixing, and hygroscopic growth spectra can be divided into three different hygroscopic modes: a less hygroscopic mode (GF < 1.3), a hygroscopic mode (GF 1.3–1.7) and a more hygroscopic mode (GF > 1.7). The majority of particles measured can be classified as being in either the less hygroscopic mode or the hygroscopic mode, and only few of them have more hygroscopic properties. The degree of external mixing, evaluated as the fraction of time when the aerosol is found with two or more populations with different hygroscopic properties, is found to increase with particle size (average yearly values are 22, 33 and 49% for 25, 50, and 165 nm particles, respectively). The degree of external mixing is more sensitive to season than to air mass type, and it is higher in the cold seasons than in the warm seasons. This study gathers the results from one of the longest data sets of hygroscopic growth factor measurements to date, allowing a statistically relevant hygroscopic growth parameterization to be determined as a function of both air mass type and season.

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

2020 ◽  
Author(s):  
Weigang Wang ◽  
Ting Lei ◽  
Andreas Zuend ◽  
Hang Su ◽  
Yafang Cheng ◽  
...  
Keyword(s):  
Growth Factor ◽  
Relative Humidity ◽  
Ammonium Sulfate ◽  
Water Uptake ◽  
Phthalic Acid ◽  
Core Shell ◽  
Hygroscopic Growth ◽  
The Core ◽  
Mass Fractions ◽  
Shell Particles

Abstract. Aerosol mixing state regulates the interactions between water molecules and particles and thus controls the aerosol activation and hygroscopic growth, which thereby influences the visibility degradation, cloud formation, and its radiative forcing. Current studies on the mixing structure effects on aerosol hygroscopicity, however, is few reported. Here we investigated the effect of phthalic acid (PA) coatings on the hygroscopic behavior of the core-shell mixtures of ammonium sulfate (AS) with PA using a coating-hygroscopicity tandem differential mobility analyzer (coating-HTDMA). The slow increase in the hygroscopic growth factor of core-shell particles is observed with increasing thickness of coating PA prior to the DRH of AS. At RH above 80 %, a decrease in hygroscopic growth factor of particles occurs as the thickness of PA shell increases, which indicates that the increase of PA mass fractions leads to a reduction of the overall core-shell particle hygroscopicity. In addition, the use of the ZSR relation leads to the underestimation for the measured growth factors of core-shell particles without consideration of the morphological effect of core-shell particles. For the AS/PA well mixed particles, a shift of deliquescence relative humidity (DRH) of AS to lower relative humidity (RH) is observed due to the presence of PA in the well-mixed particles. The predicted hygroscopic growth factor using the ZSR relation is consistent with the measured hygroscopic growth factor of the 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 particles is slightly higher than that of the well-mixed particles with the same mass fractions of PA at RH above 80 %. For our 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 Development of an H-TDMA for long-term unattended measurement of the hygroscopic properties of atmospheric aerosol particles

2009 ◽  
Vol 2 (2) ◽  
pp. 1057-1073
Author(s):  
E. Nilsson ◽  
E. Swietlicki ◽  
S. Sjogren ◽  
J. Löndahl ◽  
M. Nyman ◽  
...  
Keyword(s):  
Growth Factor ◽  
Ammonium Sulphate ◽  
Atmospheric Aerosol ◽  
Aerosol Particles ◽  
Temperature Stability ◽  
Hygroscopic Growth ◽  
Hygroscopic Properties ◽  
Atmospheric Aerosol Particles ◽  
New Generation

Abstract. A new hygroscopic tandem differential mobility analyzer (H-TDMA) has been constructed at Lund University within the frameworks of the EU FP6 Infrastructure Project EUSAAR (http://www.eusaar.org/). The aim of this coordinated H-TDMA development is to design and evaluate a new generation of H-TDMAs that are capable of conducting long term measurements of the hygroscopic growth and state of mixing of sub-micrometer atmospheric aerosol particles at the EUSAAR aerosol super-sites across Europe. The H-TDMA constructed for this project has been validated with respect to hygroscopic growth factor, stability of relative humidity (RH), temperature stability and its ability to operate unattended for longer periods of time. When measuring growth factors of ammonium sulphate, the new H-TDMA system was found to measure within a growth factor deviation of ±0.05 compared to previously recorded data by Tang et al. (1994). The long term RH of the system has been found stable at 90.0% with a standard deviation of ±0.23% and an average temperature variability of the second DMA less than ±0.1 K. Daily automated ammonium sulphate measurements have validated the ambient measurements. The instrument is operated at the EMEP/EUSAAR background station Vavihill in the southern part of Sweden.

Determination of hygroscopic aerosol growth based on the OPC-N3 counter

2021 ◽  
Author(s):  
Katarzyna Nurowska ◽  
Grzegorz Florczyk ◽  
Agata Han ◽  
Michał Chiliński ◽  
Krzysztof Markowicz
Keyword(s):  
Growth Factor ◽  
Relative Humidity ◽  
Low Cost ◽  
City Center ◽  
Hygroscopic Properties ◽  
Particle Matter ◽  
First Results ◽  
The University ◽  
The City

&lt;p&gt;In this study the OPC-N3 low-cost particle matter counter was used to determine the hygroscopic properties of the aerosol. The work shows the first results of aerosol hygroscopicity conducted in Poland. The study was performed during Spring 2020 (lock-down period) and Winter 2020/2021. The research was conducted in the Geophysics Institute at the University of Warsaw, close to the city center.&amp;#160;&lt;/p&gt;&lt;p&gt;Two OPC-N3 sensors were connected to the outlet from two legs of the Aerosol Conditioning System ACS1000. In one of them, low relative humidity was kept at the level of 20%, and in the other, the relative humidity was changed in the range of 50-90% in cycles.&lt;/p&gt;&lt;p&gt;The calculation of growth factor was done by dividing the PM1 measured from wet pipe by PM1 measured in the dry channel. The hygroscopicity parameter &amp;#954; was calculated from &amp;#954;-K&amp;#246;hler theory, showing a fluctuation of the &amp;#954; parameter which depends on aerosol type.&lt;/p&gt;&lt;p&gt;The variability of &amp;#954; during Spring was ranging from values of 0.075 up to 0.437 (growth factor range 1.294 &amp;#8211; 2.625).&amp;#160; The observed &amp;#954; for Winter oscillates between 0.018 - 0.077 (growth factor range 1.057 &amp;#8211; 1.246). The values of hygroscopicity of aerosol in winter are smaller than the ones corresponding to Spring, in line with respect to previous literature reports.&lt;/p&gt;&lt;p&gt;The study shows possibility to use OPC-N3 for calculation of the hygroscopic properties of the aerosol, however it means that the measurements of PM done by OPC-N3 can be biased by high relative humidity.&lt;/p&gt;

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