Hygroscopic growth and water uptake kinetics of two-phase aerosol particles consisting of ammonium sulfate, adipic and humic acid mixtures

Sjögren, S.; Gysel, M.; Weingärtner, E.; Baltensperger, Urs; Cubison, M. J.; Coe, Hugh; Zardini, Alessandro; Marcolli, Claudia; Krieger, Ulrich K.; Peter, Thomas

doi:10.1016/j.jaerosci.2006.11.005

Cited by 220 publications

(244 citation statements)

References 44 publications

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“…The set temperature of the Nafion corresponds to the dew point needed to create the desired RH, given the temperature of DMA-II and with an empirically determined offset to account for imperfect efficiency of humidification. The residence time between the humidifier and DMA-II is ∼6 s, which is enough time to equilibrate to this new RH such that the measured size reflects the growth factor at the measured RH (Snider and Petters 2008), provided that there are no kinetic limitations to water uptake which may bias HTDMA results (Sjogren et al 2007). The humidity in the Nafion flow area approaches 100% RH, as a function of the flow rate and Nafion age.…”

Section: Humidificationmentioning

confidence: 99%

Accurate Determination of Aerosol Activity Coefficients at Relative Humidities up to 99% Using the Hygroscopicity Tandem Differential Mobility Analyzer Technique

Petters

2013

Aerosol Science and Technology

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Aerosol water content plays an important role in aqueous phase reactions, in controlling visibility, and in cloud formation processes. One way to quantify aerosol water content is to measure hygroscopic growth using the hygroscopicity tandem differential mobility analyzer (HTDMA) technique. However, the HTDMA technique becomes less reliable at relative humidity (RH) >90% due to the difficulty of controlling temperature and RH inside the second DMA. For this study, we have designed and implemented a new HTDMA system with improved temperature and RH control. Temperature stability in the second DMA was achieved to ±0.02• C tolerance by implementing active control using thermoelectric heat exchangers and PID control loops. The DMA size resolution was increased by operating high-flow DMA columns at a sheath:sample flow ratio of 15:0.5. This improved size resolution allowed for improving the accuracy of the RH sensors by interspersing ammonium sulfate reference scans at high frequency. We present growth factor data for pure compounds at RH up to 99% and compare the data to theoretical values and to available bulk water activity data. With this HTDMA instrument and method, the osmotic coefficients of spherical, nonvolatile aerosols of known composition between 30 and 200 nm in diameter can be determined within ±20%. We expect that data from this instrument will lead to an improvement of aerosol water content models by contributing to the understanding of aerosol water uptake at high RH.

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Section: Humidificationmentioning

confidence: 99%

Accurate Determination of Aerosol Activity Coefficients at Relative Humidities up to 99% Using the Hygroscopicity Tandem Differential Mobility Analyzer Technique

Petters

2013

Aerosol Science and Technology

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“…It is worth mentioning that the normalization of f (RH) (see Sect. 2.2) may underestimate f (RH) to some extent, since some organics (e.g., humic acid sodium) take up water even when RH < 40 % (Sjogren et al, 2007;Dick et al, 2000). To evaluate its impact, we calculated the raw f (40 %) value without the normalization.…”

Section: Measurement System and Data Processingmentioning

confidence: 99%

Observations of relative humidity effects on aerosol light scattering in the Yangtze River Delta of China

et al. 2015

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Abstract. Scattering of solar radiation by aerosol particles is highly dependent on relative humidity (RH) as hygroscopic particles take up water with increasing RH. To achieve a better understanding of the effect of aerosol hygroscopic growth on light scattering properties and radiative forcing, the aerosol scattering coefficients at RH in the range of 40 to ∼ 90 % were measured using a humidified nephelometer system in the Yangtze River Delta of China in March 2013. In addition, the aerosol size distribution and chemical composition were measured. During the observation period, the mean and standard deviation (SD) of enhancement factors at RH = 85 % for the scattering coefficient (f (85 %)), backscattering coefficient (f b (85 %)), and hemispheric backscatter fraction (f β (85 %)) were 1.58 ± 0.12, 1.25 ± 0.07, and 0.79 ± 0.04, respectively, i.e., aerosol scattering coefficient and backscattering coefficient increased by 58 and 25 % as the RH increased from 40 to 85 %. Concurrently, the aerosol hemispheric backscatter fraction decreased by 21 %. The relative amount of organic matter (OM) or inorganics in PM 1 was found to be a main factor determining the magnitude of f (RH). The highest values of f (RH) corresponded to the aerosols with a small fraction of OM, and vice versa. The relative amount of NO − 3 in fine particles was strongly correlated with f (85 %), which suggests that NO − 3 played a vital role in aerosol hygroscopic growth during this study. The mass fraction of nitrate also had a close relationship to the curvature of the humidograms; higher mass fractions of nitrate were associated with humidograms that had the least curvature. Aerosol hygroscopic growth caused a 47 % increase in the calculated aerosol direct radiative forcing at 85 % RH, compared to the forcing at 40 % RH.

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“…The growth factor (GF) of a mixture (GF mix ) can be estimated from the GFs of the pure components and their respective volume fractions (ε) using the Zdanovskii-Stokes-Robinson relation (ZSR relation; Sjogren et al, 2007;Stokes and Robinson, 1966):…”

Section: Hygroscopic and Optical Growth Calculationsmentioning

confidence: 99%

Absorbing aerosols at high relative humidity: linking hygroscopic growth to optical properties

et al. 2012

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Abstract. One of the major uncertainties in the understanding of Earth's climate system is the interaction between solar radiation and aerosols in the atmosphere. Aerosols exposed to high humidity will change their chemical, physical, and optical properties due to their increased water content. To model hydrated aerosols, atmospheric chemistry and climate models often use the volume weighted mixing rule to predict the complex refractive index (RI) of aerosols when they interact with high relative humidity, and, in general, assume homogeneous mixing. This study explores the validity of these assumptions. A humidified cavity ring down aerosol spectrometer (CRD-AS) and a tandem hygroscopic DMA (differential mobility analyzer) are used to measure the extinction coefficient and hygroscopic growth factors of humidified aerosols, respectively. The measurements are performed at 80 % and 90 %RH at wavelengths of 532 nm and 355 nm using size-selected aerosols with different degrees of absorption; from purely scattering to highly absorbing particles. The ratio of the humidified to the dry extinction coefficients (f RH ext (%RH, Dry)) is measured and compared to theoretical calculations based on Mie theory. Using the measured hygroscopic growth factors and assuming homogeneous mixing, the expected RIs using the volume weighted mixing rule are compared to the RIs derived from the extinction measurements.We found a weak linear dependence or no dependence of f RH(%RH, Dry) with size for hydrated absorbing aerosols in contrast to the non-monotonically decreasing behavior with size for purely scattering aerosols. No discernible difference could be made between the two wavelengths used. Less than 7 % differences were found between the real parts of the complex refractive indices derived and those calculated using the volume weighted mixing rule, and the imaginary parts had up to a 20 % difference. However, for substances with growth factor less than 1.15 the volume weighted mixing rule assumption needs to be taken with caution as the imaginary part of the complex RI can be underestimated.

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Hygroscopic growth and water uptake kinetics of two-phase aerosol particles consisting of ammonium sulfate, adipic and humic acid mixtures

Cited by 220 publications

References 44 publications

Accurate Determination of Aerosol Activity Coefficients at Relative Humidities up to 99% Using the Hygroscopicity Tandem Differential Mobility Analyzer Technique

Accurate Determination of Aerosol Activity Coefficients at Relative Humidities up to 99% Using the Hygroscopicity Tandem Differential Mobility Analyzer Technique

Observations of relative humidity effects on aerosol light scattering in the Yangtze River Delta of China

Absorbing aerosols at high relative humidity: linking hygroscopic growth to optical properties

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