scholarly journals Efficacy of a portable, moderate-resolution, fast-scanning differential mobility analyzer for ambient aerosol size distribution measurements

2021 ◽  
Vol 14 (6) ◽  
pp. 4507-4516
Author(s):  
Stavros Amanatidis​​​​​​​ ◽  
Yuanlong Huang ◽  
Buddhi Pushpawela ◽  
Benjamin C. Schulze ◽  
Christopher M. Kenseth ◽  
...  
Keyword(s):  
Size Distribution ◽  
Size Range ◽  
Aerosol Size Distribution ◽  
Size Distributions ◽  
Differential Mobility Analyzer ◽  
Differential Mobility ◽  
Sheath Flow ◽  
Ambient Aerosol ◽  
Aerosol Flow ◽  
Mobility Resolution

Abstract. Ambient aerosol size distributions obtained with a compact scanning mobility analyzer, the “Spider” differential mobility analyzer (DMA), are compared to those obtained with a conventional mobility analyzer, with specific attention to the effect of mobility resolution on the measured size distribution parameters. The Spider is a 12 cm diameter radial differential mobility analyzer that spans the 10–500 nm size range with 30 s mobility scans. It achieves its compact size by operating at a nominal mobility resolution R=3 (sheath flow = 0.9 L min−1; aerosol flow = 0.3 L min−1) in place of the higher ratio of sheath flow to aerosol flow commonly used. The question addressed here is whether the lower resolution is sufficient to capture key characteristics of ambient aerosol size distributions. The Spider, operated at R=3 with 30 s up- and downscans, was co-located with a TSI 3081 long-column mobility analyzer, operated at R=10 with a 360 s sampling duty cycle. Ambient aerosol data were collected over 26 consecutive days of continuous operation, in Pasadena, CA. Over the 17–500 nm size range, the two instruments exhibit excellent correlation in the total particle number concentrations and geometric mean diameters, with regression slopes of 1.13 and 1.00, respectively. Our results suggest that particle sizing at a lower resolution than typically employed may be sufficient to obtain key properties of ambient size distributions, at least for these two moments of the size distribution. Moreover, it enables better counting statistics, as the wider transfer function for a given aerosol flow rate results in a higher counting rate.

scholarly journals Efficacy of a portable, moderate-resolution, fast-scanning DMA for ambient aerosol size distribution measurements

2021 ◽  
Author(s):  
Stavros Amanatidis ◽  
Yuanlong Huang ◽  
Buddhi Pushpawela ◽  
Benjamin C. Schulze ◽  
Christopher M. Kenseth ◽  
...  
Keyword(s):  
Size Distribution ◽  
Size Range ◽  
Geometric Mean ◽  
Aerosol Size Distribution ◽  
Size Distributions ◽  
Ambient Aerosol ◽  
Aerosol Flow ◽  
Compact Size ◽  
Regression Slopes ◽  
Mobility Resolution

Abstract. Ambient aerosol size distributions obtained with a compact, scanning mobility analyzer, the Spider DMA, are compared to those obtained with a conventional mobility analyzer, with specific attention to the effect of mobility resolution on the measured size distribution parameters. The Spider is a 12-cm diameter radial differential mobility analyzer that spans the 10–500 nm size range with 30s mobility scans. It achieves its compact size by operating at a nominal mobility resolution R = 3 (sheath flow = 0.9 L/min, aerosol flow = 0.3 L/min), in place of the higher sheath-to-aerosol flow commonly used. The question addressed here is whether the lower resolution is sufficient to capture the dynamics and key characteristics of ambient aerosol size distributions. The Spider, operated at R = 3 with 30s up and down scans, was collocated with a TSI 3081 long-column mobility analyzer, operated at R = 10 with a 360s sampling duty cycle. Ambient aerosol data were collected over 26 consecutive days of continuous operation, in Pasadena, CA. Over the 20–500 nm size range, the two instruments exhibit excellent correlation in the total particle number concentrations and geometric mean diameters, with regression slopes of 1.13 and 1.00, respectively. Our results suggest that particle sizing at a lower resolution than typically employed is sufficient in obtaining the key properties of ambient size distributions.

scholarly journals Development of a new Nano-particle sizer equipped with a 12 channel multi-port differential mobility analyzer and multi-condensation particle counters

2019 ◽  
Author(s):  
Hong Ku Lee ◽  
Handol Lee ◽  
Kang-Ho Ahn
Keyword(s):  
Particle Size ◽  
Steady State ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Particle Concentration ◽  
Size Distributions ◽  
Nano Particle ◽  
Differential Mobility Analyzer ◽  
Differential Mobility ◽  
Particle Sizer

Abstract. Measuring particle size distributions precisely is an important concern in addressing environmental and human health-related issues. To measure particle size distribution, a scanning mobility particle sizer (SMPS) is often used. However, it is difficult to analyze particle size distribution under fast-changing concentration conditions because the SMPS cannot respond fast enough to reflect current conditions due to the time necessary for voltage scanning. In this research, we developed a new Nano-particle sizer (NPS), which consists of a multi-port differential mobility analyzer (MP-DMA) with 12 sampling ports and multi-condensation particle counters (M-CPCs) that simultaneously measure concentrations of particles classified by the sampling ports. The M-CPC can completely condense particles larger than 10 nm, and the total particle concentrations measured by each homemade CPC in the M-CPCs and an electrometer were in agreement up to 20,000 # cm−3. For particle classification tests on the MP-DMA, geometric standard deviations of the size distributions of classified particles were estimated in the range of 1.035–1.066. We conducted size distribution measurements under steady-state conditions using an aerosol generator and under unsteady conditions by switching the aerosol supply on/off. The data obtained by the NPS corresponded closely with the SMPS measurement data for the steady-state particle concentration case. In addition, the NPS could successfully capture the changes in particle size distribution under fast-changing particle concentration conditions. For the last, we presented the NPS measurement results of size distributions in common situation (cooking) as an exemplary real-world application.

scholarly journals Development of a new nanoparticle sizer equipped with a 12-channel multi-port differential mobility analyzer and multi-condensation particle counters

2020 ◽  
Vol 13 (3) ◽  
pp. 1551-1562
Author(s):  
Hong Ku Lee ◽  
Handol Lee ◽  
Kang-Ho Ahn
Keyword(s):  
Particle Size ◽  
Steady State ◽  
Size Distribution ◽  
Particle Concentration ◽  
Measurement Data ◽  
Size Distributions ◽  
Differential Mobility Analyzer ◽  
Particle Size Distributions ◽  
Scanning Mobility Particle Sizer ◽  
Differential Mobility

Abstract. Measuring particle size distributions precisely is an important concern in addressing environmental and human health-related issues. To measure particle size distributions, a scanning mobility particle sizer (SMPS) is often used. However, it is difficult to analyze particle size distributions under fast-changing concentration conditions because the SMPS cannot respond fast enough to reflect current conditions due to the time necessary for voltage scanning. In this research, we developed a new nanoparticle sizer (NPS), which consists of a multi-port differential mobility analyzer (MP-DMA) with 12 sampling ports and multi-condensation particle counters (M-CPCs) that simultaneously measure concentrations of particles classified by the sampling ports. The M-CPC can completely condense particles larger than 10 nm, and the total particle concentrations measured by each CPC in the M-CPCs and an electrometer were in agreement up to 20 000 no.cm-3. We conducted size distribution measurements under steady-state conditions using an aerosol generator and under unsteady conditions by switching the aerosol supply on or off. The data obtained by the NPS corresponded closely to the SMPS measurement data for the steady-state particle concentration case. In addition, the NPS could successfully capture the changes in particle size distribution under fast-changing particle concentration conditions. Finally, we present NPS measurement results of size distributions in a common situation (cooking) as an exemplary real-world application.

Long-term aerosol number size distributions down to 1 nm in urban Beijing

2021 ◽  
Author(s):  
Chenjuan Deng ◽  
Yiran Li ◽  
Xiaotong Chen ◽  
Jingkun Jiang
Keyword(s):  
Size Distribution ◽  
Size Range ◽  
Particle Diameter ◽  
Small Diameter ◽  
Aerosol Size Distribution ◽  
Size Distributions ◽  
Diurnal Patterns ◽  
The Mean ◽  
Meteorological Analysis

<p>To reveal the characteristics of aerosols in polluted environments, we measured aerosol number size distributions in the size range of ~1 nm – 10 μm during 2018- 2020 in urban Beijing. As a vital process influencing the aerosol size distributions, new particle formation (NPF) events were frequently observed in urban Beijing. We classified NPF days into typical NPF days with a burst of sub‑3 nm particles and those with few sub‑3 nm particles. We examined their characteristics and possible reasons. The mean aerosol number size distributions were clearly different and the peak particle diameter was ~1.5 nm and 12 nm, respectively. For those with a burst of sub-3 nm particles, however, the peak diameter shifts from small diameter to larger particle diameters as the aerosol size distribution evolves during the NPF process and then becomes similar to those with few sub-3 nm particles. Meteorological analysis indicates that airmass movement may account for these observations. Despite these differences, similar diurnal patterns were observed on most days in urban Beijing, i.e., drastic change in aerosol size distributions happens around 4:00 a.m. and 4:00 p.m.</p>

Determination of atmospheric aerosol particle size distribution and visibility using a mobile laboratory

1982 ◽  
Vol 60 (8) ◽  
pp. 1101-1107
Author(s):  
C. V. Mathai ◽  
A. W. Harrison
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Atmospheric Aerosols ◽  
Suspended Particle ◽  
Aerosol Size Distribution ◽  
Size Distributions ◽  
Mobile Laboratory ◽  
Mean Values ◽  
The City

As part of an ongoing general research program on the effects of atmospheric aerosols on visibility and its dependence on aerosol size distributions in Calgary, this paper presents the results of a comparative study of particle size distribution and visibility in residential (NW) and industrial (SE) sections of the city using a mobile laboratory. The study was conducted in the period October–December, 1979. An active scattering aerosol spectrometer measured the size distributions and the corresponding visibilities were deduced from scattering coefficients measured with an integrating nephelometer.The results of this transit study show significantly higher suspended particle concentrations and reduced visibilities in the SE than in the NW. The mean values of the visibilities are 44 and 97 km for the SE and the NW respectively. The exponent of R (particle radius) in the power law aerosol size distribution has a mean value of −3.36 ± 0.24 in the SE compared with the corresponding value of −3.89 ± 0.39 for the NW. These results arc in good agreement with the observations of Alberta Environment; however, they are in contradiction with a recent report published by the City of Calgary.

scholarly journals An investigation of processes controlling the evolution of the boundary layer aerosol size distribution properties at the Swedish background station Aspvreten

2004 ◽  
Vol 4 (4) ◽  
pp. 4507-4543 ◽  
Author(s):  
P. Tunved ◽  
J. Ström ◽  
H.-C. Hansson
Keyword(s):  
Size Distribution ◽  
Wet Deposition ◽  
Source Area ◽  
Aerosol Size Distribution ◽  
Back Trajectory ◽  
Main Process ◽  
Size Distributions ◽  
Back Trajectory Analysis ◽  
The One ◽  
Precipitating Clouds

Abstract. Aerosol size distributions have been measured at the Swedish background station Aspvreten (58.8° N, 17.4° E). Different states of the aerosol were determined using a novel application of cluster analysis. The analysis resulted in eight different clusters capturing the different stages of the aerosol lifecycle. The aerosol was interpreted as belonging to fresh, intermediate and aged type of size distribution and different magnitudes thereof. With aid of back trajectory analysis we present statistics concerning the relation of source area and different meteorological parameters using a non-lagrangian approach. Source area is argued to be important although not sufficient to describe the observed aerosol properties. Especially processing by clouds and precipitation is shown to be crucial for the evolution of the aerosol size distribution. As much as 60% of the observed size distributions present features likely related to cloud processes or wet deposition. The lifetime properties of different sized aerosols are discussed by means of measured variability. Processing by non-precipitating clouds most obviously affect aerosols in the size range 100 nm and larger. This indicates an approximate limit for activation in clouds to 100 nm in this type of environment. The aerosol lifecycle is discussed. Size distributions bearing signs of recent new particle formation (~30% of the observed size distributions) represent the first stage in the lifecycle. Aging may proceed in two directions: either growth by condensation and coagulation or processing by non-precipitating clouds. In both cases mass is accumulated. Wet removal is the main process capable of removing aerosol mass. Wet deposition is argued to be an important mechanism in reaching a state where nucleation may occur (i.e. sufficiently low aerosol surface area) in environments similar to the one studied.

scholarly journals Quantifying aerosol size distributions and their temporal variability in the Southern Great Plains, USA

2019 ◽  
Vol 19 (18) ◽  
pp. 11985-12006 ◽  
Author(s):  
Peter J. Marinescu ◽  
Ezra J. T. Levin ◽  
Don Collins ◽  
Sonia M. Kreidenweis ◽  
Susan C. van den Heever
Keyword(s):  
Size Distribution ◽  
Great Plains ◽  
Diurnal Cycle ◽  
Particle Formation ◽  
Aerosol Size Distribution ◽  
Size Distributions ◽  
New Particle Formation ◽  
Scanning Mobility Particle Sizer ◽  
Southern Great Plains ◽  
Particle Sizer

Abstract. A quality-controlled, 5-year dataset of aerosol number size distributions (particles with diameters (Dp) from 7 nm through 14 µm) was developed using observations from a scanning mobility particle sizer, aerodynamic particle sizer, and a condensation particle counter at the Department of Energy's Southern Great Plains (SGP) site. This dataset was used for two purposes. First, typical characteristics of the aerosol size distribution (number, surface area, and volume) were calculated for the SGP site, both for the entire dataset and on a seasonal basis, and size distribution lognormal fit parameters are provided. While the median size distributions generally had similar shapes (four lognormal modes) in all the seasons, there were some significant differences between seasons. These differences were most significant in the smallest particles (Dp<30 nm) and largest particles (Dp>800 nm). Second, power spectral analysis was conducted on this long-term dataset to determine key temporal cycles of total aerosol concentrations, as well as aerosol concentrations in specified size ranges. The strongest cyclic signal was associated with a diurnal cycle in total aerosol number concentrations that was driven by the number concentrations of the smallest particles (Dp<30 nm). This diurnal cycle in the smallest particles occurred in all seasons in ∼50 % of the observations, suggesting a persistent influence of new particle formation events on the number concentrations observed at the SGP site. This finding is in contrast with earlier studies that suggest new particle formation is observed primarily in the springtime at this site. The timing of peak concentrations associated with this diurnal cycle was shifted by several hours depending on the season, which was consistent with seasonal differences in insolation and boundary layer processes. Significant diurnal cycles in number concentrations were also found for particles with Dp between 140 and 800 nm, with peak concentrations occurring in the overnight hours, which were primarily associated with both nitrate and organic aerosol cycles. Weaker cyclic signals were observed for longer timescales (days to weeks) and are hypothesized to be related to the timescales of synoptic weather variability. The strongest periodic signals (3.5–5 and 7 d cycles) for these longer timescales varied depending on the season, with no cyclic signals and the lowest variability in the summer.

scholarly journals Cloud Activating Properties of Aerosol Observed during CELTIC

2007 ◽  
Vol 64 (2) ◽  
pp. 441-459 ◽  
Author(s):  
Craig A. Stroud ◽  
Athanasios Nenes ◽  
Jose L. Jimenez ◽  
Peter F. DeCarlo ◽  
J. Alex Huffman ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Size Distribution ◽  
Organic Aerosol ◽  
Aerosol Size Distribution ◽  
Model Bias ◽  
Aerosol Composition ◽  
Ambient Aerosol ◽  
Aerosol Mass ◽  
Mass Fractions ◽  
Mass Size

Abstract Measurements of aerosol size distribution, chemical composition, and cloud condensation nuclei (CCN) concentration were performed during the Chemical Emission, Loss, Transformation, and Interactions with Canopies (CELTIC) field program at Duke Forest in North Carolina. A kinetic model of the cloud activation of ambient aerosol in the chamber of the CCN instrument was used to perform an aerosol–CCN closure study. This study advances prior investigations by employing a novel fitting algorithm that was used to integrate scanning mobility particle sizer (SMPS) measurements of aerosol number size distribution and aerosol mass spectrometer (AMS) measurements of the mass size distribution for sulfate, nitrate, ammonium, and organics into a single, coherent description of the ambient aerosol in the size range critical to aerosol activation (around 100-nm diameter). Three lognormal aerosol size modes, each with a unique internally mixed composition, were used as input into the kinetic model. For the two smaller size modes, which control CCN number concentration, organic aerosol mass fractions for the defined cases were between 58% and 77%. This study is also unique in that the water vapor accommodation coefficient was estimated based on comparing the initial timing for CCN activation in the instrument chamber with the activation predicted by the kinetic model. The kinetic model overestimated measured CCN concentrations, especially under polluted conditions. Prior studies have attributed a positive model bias to an incomplete understanding of the aerosol composition, especially the role of organics in the activation process. This study shows that including measured organic mass fractions with an assumed organic aerosol speciation profile (pinic acid, fulvic acid, and levoglucosan) and an assumed organic aerosol solubility of 0.02 kg kg−1 still resulted in a significant model positive bias for polluted case study periods. The slope and y intercept for the CCN predicted versus CCN observed regression was found to be 1.9 and −180 cm−3, respectively. The overprediction generally does not exceed uncertainty limits but is indicative that a bias exists in the measurements or application of model. From this study, uncertainties in the particle number and mass size distributions as the cause for the model bias can be ruled out. The authors are also confident that the model is including the effects of growth kinetics on predicted activated number. However, one cannot rule out uncertainties associated with poorly characterized CCN measurement biases, uncertainties in assumed organic solubility, and uncertainties in aerosol mixing state. Sensitivity simulations suggest that assuming either an insoluble organic fraction or external aerosol mixing were both sufficient to reconcile the model bias.

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