Size distributions of sea-source aerosol particles: A physical explanation of observed nearshore versus open-sea differences

Abstract. Here we present a method to systematically investigate single aerosol particles collected on formvar film supported by a copper grid, with Scanning Electron Microscopy (SEM) operating at low accelerating voltage. The method enabled us to observe the surface of the sample grid at high resolution. Subsequent processing of the images with digital image analysis provided a statistically and quantitative size resolved information on the particle population including their morphology on the film. The quality of the presented method was established using polystyrene nanospheres as standards in the size range expected for ambient aerosol particles over remote marine areas (20–900 nm in diameter). The sizing was found to be critically dependent on the contrasting properties of the particles towards the collection substrate. The relative standard deviation of the diameters of polystyrene nanospheres was better than 10% for sizes larger than 40 nm and 18% for 21 nm particles compared with the manufacturer's certificate. The size distributions derived from the microscope images of airborne aerosols collected during a research expedition to north of 80° N in the summer of 2008 were compared with simultaneously collected number particle size distributions seen by a Twin Differential Mobility Particle Sizer. We captured a representative fraction of the aerosol particles with SEM and were able to causally relate the determined morphological properties of the aerosol under investigation to aerosol transformation processes in air being advected from the marginal ice edge/open sea south of 80° N.

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Inhalers and nebulizers: basic principles and preliminary measurements

EPJ Web of Conferences ◽

10.1051/epjconf/201818002068 ◽

2018 ◽

Vol 180 ◽

pp. 02068

Author(s):

Ondrej Misik ◽

Frantisek Lizal ◽

Vahid Farhikhteh Asl ◽

Miloslav Belka ◽

Jan Jedelsky ◽

...

Keyword(s):

Hospital Care ◽

Aerosol Particles ◽

Experimental Setup ◽

Size Distributions ◽

Particle Size Distributions ◽

Basic Principles ◽

Physical Mechanisms ◽

Inhaled Particles ◽

Human Airways ◽

Inhaled Medication

Inhalers are hand-held devices which are used for administration of therapeutic aerosols via inhalation. Nebulizers are larger devices serving for home and hospital care using inhaled medication. This contribution describes the basic principles of dispersion of aerosol particles used in various types of inhalers and nebulizers, and lists the basic physical mechanisms contributing to the deposition of inhaled particles in the human airways. The second part of this article presents experimental setup, methodology and preliminary results of particle size distributions produced by several selected inhalers and nebulizers.

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Size-resolved particle number emissions in Beijing determined from measured particle size distributions

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-11329-2020 ◽

2020 ◽

Vol 20 (19) ◽

pp. 11329-11348 ◽

Cited By ~ 2

Author(s):

Jenni Kontkanen ◽

Chenjuan Deng ◽

Yueyun Fu ◽

Lubna Dada ◽

Ying Zhou ◽

...

Keyword(s):

Particle Size ◽

Air Quality ◽

Particle Number ◽

Aerosol Particles ◽

Urban Environments ◽

Integrated Assessment Model ◽

Assessment Model ◽

Size Distributions ◽

Particle Size Distributions ◽

Measured Particle

Abstract. The climate and air quality effects of aerosol particles depend on the number and size of the particles. In urban environments, a large fraction of aerosol particles originates from anthropogenic emissions. To evaluate the effects of different pollution sources on air quality, knowledge of size distributions of particle number emissions is needed. Here we introduce a novel method for determining size-resolved particle number emissions, based on measured particle size distributions. We apply our method to data measured in Beijing, China, to determine the number size distribution of emitted particles in a diameter range from 2 to 1000 nm. The observed particle number emissions are dominated by emissions of particles smaller than 30 nm. Our results suggest that traffic is the major source of particle number emissions with the highest emissions observed for particles around 10 nm during rush hours. At sizes below 6 nm, clustering of atmospheric vapors contributes to calculated emissions. The comparison between our calculated emissions and those estimated with an integrated assessment model GAINS (Greenhouse Gas and Air Pollution Interactions and Synergies) shows that our method yields clearly higher particle emissions at sizes below 60 nm, but at sizes above that the two methods agree well. Overall, our method is proven to be a useful tool for gaining new knowledge of the size distributions of particle number emissions in urban environments and for validating emission inventories and models. In the future, the method will be developed by modeling the transport of particles from different sources to obtain more accurate estimates of particle number emissions.

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In situ observations of aerosol particles remaining from evaporated cirrus crystals: Comparing clean and polluted air masses

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-2-1599-2002 ◽

2002 ◽

Vol 2 (5) ◽

pp. 1599-1633 ◽

Cited By ~ 5

Author(s):

M. Seifert ◽

J. Ström ◽

R. Krejci ◽

A. Minikin ◽

A. Petzold ◽

...

Keyword(s):

Southern Hemisphere ◽

Northern Hemisphere ◽

Aerosol Particles ◽

Pollution Level ◽

Size Distributions ◽

Number Density ◽

Particle Volume ◽

The North ◽

In Situ Observations

Abstract. In situ observations of aerosol particles contained in cirrus crystals are presented and compared to interstitial aerosol size distributions (non-activated particles in between the cirrus crystals). The observations were conducted in cirrus clouds in the Southern and Northern Hemisphere mid-latitudes during the INCA project. The first campaign in March and April 2000 was performed from Punta Arenas, Chile (54° S) in pristine air. The second campaign in September and October 2000 was performed from Prestwick, Scotland (53° N) in the vicinity of the North Atlantic flight corridor. Size distribution measurements of crystal residuals (particles remaining after evaporation of the crystals) show that small aerosol particles (Dp < 0.1µm) dominate the number density of residuals. The crystal residual size distributions were significantly different in the two campaigns. On average the residual size distributions were shifted towards larger sizes in the Southern Hemisphere. For a given integral residual number density, the calculated particle volume was on average three times larger in the Southern Hemisphere. This may be of significance to the vertical redistribution of aerosol mass by clouds in the tropopause region. In both campaigns the mean residual size increased with increasing crystal number density. The observations of ambient aerosol particles were consistent with the expected higher pollution level in the Northern Hemisphere. The fraction of residual particles only contributes to approximately a percent or less of the total number of particles, which is the sum of the residual and interstitial particles.

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Mass Extinction Efficiency Approximation for Polydispersed Aerosol Using Harmonic Mean-Type Approximation

Applied Sciences ◽

10.3390/app10238637 ◽

2020 ◽

Vol 10 (23) ◽

pp. 8637

Author(s):

Junshik Um ◽

Seonghyeon Jang ◽

Young Jun Yoon ◽

Seoung Soo Lee ◽

Ji Yi Lee ◽

...

Keyword(s):

Optical Properties ◽

Chemical Composition ◽

Extinction Coefficient ◽

Mass Extinction ◽

Aerosol Particles ◽

Size Distributions ◽

Extinction Efficiency ◽

Type Approximation ◽

Aerosol Mass ◽

Mass Extinction Efficiency

Among many parameters characterizing atmospheric aerosols, aerosol mass extinction efficiency (MEE) is important for understanding the optical properties of aerosols. MEE is expressed as a function of the refractive indices (i.e., composition) and size distributions of aerosol particles. Aerosol MEE is often considered as a size-independent constant that depends only on the chemical composition of aerosol particles. The famous Malm’s reconstruction equation and subsequent revised methods express the extinction coefficient as a function of aerosol mass concentration and MEE. However, the used constant MEE does not take into account the effect of the size distribution of polydispersed chemical composition. Thus, a simplified expression of size-dependent MEE is required for accurate and conventional calculations of the aerosol extinction coefficient and also other optical properties. In this study, a simple parameterization of MEE of polydispersed aerosol particles was developed. The geometric volume–mean diameters of up to 10 µm with lognormal size distributions and varying geometric standard deviations were used to represent the sizes of various aerosol particles (i.e., ammonium sulfate and nitrate, elemental carbon, and sea salt). Integrating representations of separate small mode and large mode particles using a harmonic mean-type approximation generated the flexible and convenient parameterizations of MEE that can be readily used to process in situ observations and adopted in large-scale numerical models. The calculated MEE and the simple forcing efficiency using the method developed in this study showed high correlations with those calculated using the Mie theory without losing accuracy.

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The mathematical principles and design of the NAIS – a spectrometer for the measurement of cluster ion and nanometer aerosol size distributions

Atmospheric Measurement Techniques ◽

10.5194/amt-6-1061-2013 ◽

2013 ◽

Vol 6 (4) ◽

pp. 1061-1071 ◽

Cited By ~ 69

Author(s):

S. Mirme ◽

A. Mirme

Keyword(s):

Size Range ◽

Aerosol Particles ◽

Charged Particles ◽

Cluster Ions ◽

Size Distributions ◽

Neutral Cluster ◽

Design Data ◽

Cluster Ion ◽

Principles Of Design ◽

Spectrum Deconvolution

Abstract. The paper describes the Neutral cluster and Air Ion Spectrometer (NAIS) – a multichannel aerosol instrument capable of measuring the distribution of ions (charged particles and cluster ions) of both polarities in the electric mobility range from 3.2 to 0.0013 cm2 V−1 s−1 and the distribution of aerosol particles in the size range from 2.0 to 40 nm. We introduce the principles of design, data processing and spectrum deconvolution of the instrument.

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Change in Mass Size Distributions of Ambient Aerosol Particles during Asian Dust Storm Event in Late Fall at an Urban Site of Gwangju

Journal of Korean Society for Atmospheric Environment ◽

10.5572/kosae.2019.35.4.502 ◽

2019 ◽

Vol 35 (4) ◽

pp. 502-515 ◽

Cited By ~ 1

Author(s):

Seungshik Park

Keyword(s):

Dust Storm ◽

Aerosol Particles ◽

Asian Dust ◽

Urban Site ◽

Storm Event ◽

Size Distributions ◽

Asian Dust Storm ◽

Late Fall ◽

Dust Storm Event ◽

Mass Size

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On the Variability of Drop Size Distributions over Areas

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-14-0258.1 ◽

2015 ◽

Vol 72 (4) ◽

pp. 1386-1397 ◽

Cited By ~ 14

Author(s):

A. R. Jameson ◽

M. L. Larsen ◽

A. B. Kostinski

Keyword(s):

Drop Size ◽

Network Size ◽

Drop Diameter ◽

Size Distributions ◽

Physical Explanation ◽

Spatial Correlation Function ◽

Drop Size Distributions ◽

The Fourier Transform ◽

D Values ◽

Physical Reasons

Abstract Past studies of the variability of drop size distributions (DSDs) have used moments of the distribution such as the mass-weighted mean drop size as proxies for the entire size distribution. In this study, however, the authors separate the total number of drops Nt from the DSD leaving the probability size distributions (PSDs); that is, DSD = Nt × PSD. The variability of the PSDs are then considered using the frequencies of size [P(D)] values at each different drop diameter P(PD | D) over an ensemble of observations collected using a network of 21 optical disdrometers. The relative dispersions RD of P(PD | D) over all the drop diameters are used as a measure of PSD variability. An intrinsic PSD is defined as an average over one or more instruments excluding zero drop counts. It is found that variability associated with an intrinsic PSD fails to characterize its true variability over an area. It is also shown that this variability is not due to sampling limitations but rather originates for physical reasons. Furthermore, this variability increases with the expansion of the network size and with increasing drop diameter. A physical explanation is that the network acts to integrate the Fourier transform of the spatial correlation function from smaller toward larger wavelengths as the network size increases so that the contributions to the variance by all spatial wavelengths being sampled also increases. Consequently, RD and, hence, PSD variability will increase as the size of the area increases.

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