Comment on “High humidity tandem differential mobility analyzer for accurate determination of aerosol hygroscopic growth, microstructure and activity coefficients over a wide range of relative humidity” by Mikhailov et al.

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.

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

10.5194/amt-2019-478 ◽

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.

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

Aerosol Science and Technology ◽

10.1080/02786826.2013.807906 ◽

2013 ◽

Vol 47 (9) ◽

pp. 991-1000 ◽

Cited By ~ 27

Author(s):

Sarah R. Suda ◽

Markus D. Petters

Keyword(s):

Activity Coefficients ◽

Accurate Determination ◽

Differential Mobility Analyzer ◽

Differential Mobility

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Hygroscopic growth and activation of HULIS particles: experimental data and a new iterative parameterization scheme for complex aerosol particles

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-13773-2007 ◽

2007 ◽

Vol 7 (5) ◽

pp. 13773-13803 ◽

Cited By ~ 3

Author(s):

M. Ziese ◽

H. Wex ◽

E. Nilsson ◽

I. Salma ◽

R. Ocskay ◽

...

Keyword(s):

Experimental Data ◽

Aerosol Particles ◽

Water Extract ◽

High Humidity ◽

Hygroscopic Growth ◽

Differential Mobility Analyzer ◽

Growth Behaviour ◽

Differential Mobility ◽

Three Samples ◽

Activation Behavior

Abstract. The hygroscopic growth and activation of two HULIS and one Aerosol-Water-Extract sample, prepared from urban-type aerosol, were investigated. All samples were extracted from filters, redissolved in water and atomized for the investigations presented here. The hygroscopic growth measurements were done using LACIS (Leipzig Aerosol Cloud Interaction Simulator) together with a HH-TDMA (High Humidity Tandem Differential Mobility Analyzer). Hygroscopic growth was determined for relative humidities up to 99.75%. The critical diameters for activation were measured using LACIS for supersaturations between 2 and 10 per mill. All three samples showed a similar hygroscopic growth behaviour, and the two HULIS samples also were similar in their activation behavior, while the Aerosol-Water-Extract turned out to be more CCN active than the HULIS samples. The experimental data was used to derive parameterizations for the hygroscopic growth and activation of HULIS particles. The concept of ρion (Wex et al., 2007a) and the Szyszkowski-equation (Szyszkowski, 1908; Facchini et al., 1999) were used for parameterizing the Raoult and the Kelvin (surface tension) terms of the Köhler equation, respectively. This concept proved to be very successful for the HULIS samples in the saturation range from relative humidities larger than 98% up to activation. However it failed for the Aerosol-Water extract.

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Water uptake and chemical composition of fresh aerosols generated in open burning of biomass

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-5165-2010 ◽

2010 ◽

Vol 10 (11) ◽

pp. 5165-5178 ◽

Cited By ~ 74

Author(s):

C. M. Carrico ◽

M. D. Petters ◽

S. M. Kreidenweis ◽

A. P. Sullivan ◽

G. R. McMeeking ◽

...

Keyword(s):

Growth Factors ◽

Chemical Composition ◽

Relative Humidity ◽

Water Uptake ◽

Particle Sizes ◽

Differential Mobility Analyzer ◽

Differential Mobility ◽

Biomass Smoke ◽

Hygroscopic Properties ◽

Wide Range

Abstract. As part of the Fire Lab at Missoula Experiments (FLAME) in 2006–2007, we examined hygroscopic properties of particles emitted from open combustion of 33 select biomass fuels. Measurements of humidification growth factors for subsaturated water relative humidity (RH) conditions were made with a hygroscopic tandem differential mobility analyzer (HTDMA) for dry particle sizes of 50, 100 and 250 nm. Results were then fit to a single-parameter model to obtain the hygroscopicity parameter, κ. Particles in freshly emitted biomass smoke exhibited a wide range of hygroscopicity (individual modes with 0

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Determining Girard Form Class in Central Hardwoods

Northern Journal of Applied Forestry ◽

10.1093/njaf/14.4.202 ◽

1997 ◽

Vol 14 (4) ◽

pp. 202-206 ◽

Cited By ~ 1

Author(s):

John C. Rennie ◽

Jack D. Leake

Keyword(s):

Direct Measurement ◽

Accurate Determination ◽

Tree Form ◽

Form Class ◽

Wide Range ◽

Close Proximity ◽

Wedge Prism ◽

The Cost ◽

Volume Estimates

Abstract Girard form class is widely used to describe tree form. Tree volume estimates change about 3% per unit change of Girard form class (Mesavage and Girard 1946). Hardwoods growing in close proximity have been observed to have a wide range in Girard form class. Accurate determination of Girard form class can therefore be important in getting accurate estimates of hardwood timber volume. However, the cost of estimating Girard form class for every tree being measured in the stand would be prohibitively expensive. Thus, estimation of average Girard form class for a stand is considered here. Three instruments used to estimate Girard form class—a Wheeler pentaprism optical caliper, a wedge prism, and a Spiegel relaskop—were compared to direct measurement. Number of sample trees to achieve desired half-widths of the confidence interval of ±1 and ±1 1/2 units of Girard form class was calculated for each method. Direct measurement requires the fewest trees to achieve the desired results. However, it requires considerably more time per tree than any of the instruments tested. The Wheeler pentaprism requires only a few more trees than direct measurement, and considerably fewer trees than either the wedge prism or the Spiegel relaskop. Use of all three instruments is hindered when understory vegetation obscures the top of the first log. North. J. Appl. For. 14(4):202-206.

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