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

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.

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-4-2581-2004 ◽

2004 ◽

Vol 4 (11/12) ◽

pp. 2581-2592 ◽

Cited By ~ 46

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 ◽

Aerosol Mass ◽

The One

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 different stages of the aerosol lifecycle. The atmospheric aerosol size distributions were interpreted as belonging to fresh, intermediate and aged types of size distribution. 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 that are likely to be related to cloud processes or wet deposition. The lifetime properties of different sized aerosols are discussed by means of measured variability of the aerosol size distribution. Processing by clouds and precipitation is shown to be especially crucial 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 indicating signs of recent new particle formation (~30% of the observed size distributions) represent the first stage in the lifecycle. Aging of the aerosol size distribution may follow two branches: 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.

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

Canadian Journal of Physics ◽

10.1139/p82-150 ◽

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.

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Size distribution and coating thickness of black carbon from the Canadian oil sands operations

10.5194/acp-2017-1015 ◽

2017 ◽

Author(s):

Yuan Cheng ◽

Shao-Meng Li ◽

Mark Gordon ◽

Peter Liu

Keyword(s):

Size Distribution ◽

Black Carbon ◽

Coating Thickness ◽

Oil Sands ◽

Radiative Forcing ◽

Climate Models ◽

Source Area ◽

Size Distributions ◽

Mixing State ◽

Earth’S Climate

Abstract. Black carbon (BC) plays an important role in the Earth’s climate system. However, parameterization of BC size and mixing state have not been well addressed in aerosol-climate models, introducing substantial uncertainties into the estimation of radiative forcing by BC. In this study, we focused on BC emissions from the massive oil sands (OS) industry in northern Alberta, based on an aircraft campaign conducted over the Athabasca OS region in 2013. A total of 14 flights were made over the OS source area, in which the aircraft was typically flown in a 4- or 5-sided polygon pattern along flight tracks encircling an OS facility. Another 3 flights were performed downwind of the OS source area, each of which involved at least three intercepting locations where the well-mixed OS plume was measured along flight tracks perpendicular to the wind direction. Comparable size distributions were observed for refractory black carbon (rBC) over and downwind of the OS facilities, with rBC mass median diameters (MMD) between ~ 135 and 145 nm that were characteristic of fresh urban emissions. This MMD range corresponded to rBC number median diameters (NMD) of ~ 60–70 nm, approximately 100 % higher than the NMD settings in some aerosol-climate models. The typical in- and out-of-plume segments of a flight, which had different rBC concentrations and photochemical ages, showed consistent rBC size distributions. Moreover, rBC size distributions remained unchanged at different downwind distances from the source area, suggesting that atmospheric aging would not necessarily change rBC size distribution. However, aging indeed influenced rBC mixing state. Coating thickness for rBC cores in the diameter range of 130–160 nm was nearly doubled within three hours when the OS plume was transported over a distance of 90 km from the source area.

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-11985-2019 ◽

2019 ◽

Vol 19 (18) ◽

pp. 11985-12006 ◽

Cited By ~ 4

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.

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Using ATom observations and models to understand what precursors drive NPF in the remote free troposphere

10.5194/egusphere-egu2020-13313 ◽

2020 ◽

Author(s):

Agnieszka Kupc ◽

Christina Williamson ◽

Anna L. Hodshire ◽

Jeffrey R. Pierce ◽

Jan Kazil ◽

...

Keyword(s):

Size Distribution ◽

Cloud Condensation Nuclei ◽

Aerosol Size Distribution ◽

Back Trajectory ◽

Initial Growth ◽

Free Troposphere ◽

Trajectory Data ◽

Organic Precursor ◽

Box Models ◽

New Particles

Current estimates suggest that globally, about one third of low-level cloud condensation nuclei (CCN) originate from new particle formation (NPF) in the free troposphere. However, the exact mechanisms of how these new particles form and grow to CCN sizes are not yet well quantified. We investigate the formation of new particles and their initial growth in the remote marine atmosphere over the Pacific and Atlantic basins (~80 &#176;N to ~86 &#176;S using (1) gas-phase and size distribution measurements (0.003-4.8 &#181;m) from the airborne-based NASA Atmospheric Tomography global survey (ATom; 2016-2018), (2) back trajectory data, and (3) two aerosol microphysics box models.In the ATom observations, newly formed particles were ubiquitous at high altitudes throughout broad regions of the tropics and subtropics under low condensation sink conditions and were associated with upwelling in convective clouds. This pattern was observed over four seasons and both ocean basins.In this study, we explore processes that govern NPF and growth in the tropical and subtropical free troposphere, discuss similarities and differences in NPF over both ocean basins, use box models to examine which nucleation schemes (e.g. binary, ternary, or charged) best explain the observations, and evaluate whether sulfuric acid precursors alone can explain the NPF and the initial particle growth. Comparing aerosol size distribution measurements with box model simulations shows that none of the NPF schemes commonly used in global models are consistent with observations, regardless of precursor concentrations. Newer schemes that incorporate organic compounds as nucleating or growth agents can plausibly replicate the observed size distributions. We conclude that organic precursor species may be particularly important in NPF in the tropical upper troposphere, even above marine regions.

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On the Quantitative Low-Level Aerosol Measurements Using Ceilometer-Type Lidar

Journal of Atmospheric and Oceanic Technology ◽

10.1175/2009jtecha1252.1 ◽

2009 ◽

Vol 26 (11) ◽

pp. 2340-2352 ◽

Cited By ~ 19

Author(s):

Anu-Maija Sundström ◽

Timo Nousiainen ◽

Tuukka Petäjä

Keyword(s):

Size Distribution ◽

Theoretical Calculations ◽

Measurement Instrument ◽

Aerosol Size Distribution ◽

Lidar Measurement ◽

Size Distributions ◽

Absolute Accuracy ◽

Particle Composition ◽

Aerosol Measurement

Abstract The objective of this work is to investigate whether a commercial ceilometer-type lidar can be used as a quantitative aerosol measurement instrument. To this end, lidar backscattering measurements are compared with exact theoretical calculations of backscattering, which are based on in situ–measured size distributions and account for uncertainties in particle composition and shape. The results show that the differences between simulated and measured backscattering remain nearly constant and within the uncertainties involved. The differences are most plausibly explained by an error in the overlap function of the lidar and/or errors in the calibration of either the lidar or the in situ instruments used to measure the aerosol size distribution. Occasionally, large differences occur that are obviously connected to the unrepresentativeness of the in situ and lidar measurement volumes because of insufficient atmospheric mixing. The results imply that the absolute accuracy of the instrument investigated might be sufficient for quantitative aerosol measurements in some applications. A fix for the overlap function, however, would be desirable.

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Determination of Fitted Size Distribution for Atmospheric Aerosols

American Journal of Undergraduate Research ◽

10.33697/ajur.2017.018 ◽

2017 ◽

Vol 14 (2) ◽

Author(s):

Kaitlin DuPaul ◽

Adam Whitten

Keyword(s):

Particle Swarm Optimization ◽

Size Distribution ◽

Atmospheric Aerosols ◽

Particle Swarm ◽

Bimodal Distribution ◽

Aerosol Size Distribution ◽

Size Distributions ◽

Swarm Optimization ◽

Large Variability ◽

Lognormal Distributions

A synthetic set of aerosol optical depths (AODs) generated from a standard set of aerosol size distributions was analyzed by a parameter based particle swarm optimization (PBPSO) routine in order to test the reproducibility of the results. Junge and lognormal size distributions were consistently reproduced. Gamma and bimodal distributions showed large variability in solutions. values were used to determine the best subset of possible solutions allowing quantification of parameters with uncertainties when using PBPSO. AODs measured by a sun photometer on a clear day (20160413) and a foggy day (20160508) were then processed by the PBPSO program for both bimodal and lognormal distributions. Results showed that in general the foggy day has smaller values indicating that the PBPSO algorithm is better able to match AODs when there is a larger aerosol load in the atmosphere. The bimodal distribution from the clear day best describes the aerosol size distribution since the values are lower. The lognormal distribution best describes the aerosol size distribution on the foggy day (20160508). KEYWORDS: Atmospheric Aerosols; Size Distributions; Junge; Bimodal; Gamma; Lognormal; Particle Swarm Optimization; Inverse Problem; Aerosol Optical Depth

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The evolution of biomass-burning aerosol size distributions due to coagulation: dependence on fire and meteorological details and parameterization

10.5194/acp-2016-9 ◽

2016 ◽

Cited By ~ 1

Author(s):

K. M. Sakamoto ◽

R. G. Stevens ◽

J. R. Pierce

Keyword(s):

Wind Speed ◽

Size Distribution ◽

Biomass Burning ◽

Independent Set ◽

Aerosol Size Distribution ◽

Size Distributions ◽

Atmospheric Conditions ◽

Mixing Depth ◽

Fire Area ◽

Biomass Burning Aerosol

Abstract. Biomass-burning aerosols have a significant effect on global and regional aerosol climate forcings. To model the magnitude of these effects accurately requires knowledge of the size distribution of the emitted and evolving aerosol particles. Current biomass-burning inventories do not include size distributions, and global and regional models generally assume a fixed size distribution from all biomass-burning emissions. However, biomass-burning size distributions evolve in the plume due to coagulation and net organic aerosol (OA) evaporation or formation, and the plume processes occur on spacial scales smaller than global/regional-model grid boxes. The extent of this size-distribution evolution is dependent on a variety of factors relating to the emission source and atmospheric conditions. Therefore, to account for biomass-burning aerosol size in global models accurately requires an effective aerosol size distribution that accounts for this sub-grid evolution and can be derived from available emissions-inventory and meteorological parameters. In this paper, we perform a detailed investigation of the effects of coagulation on the aerosol size distribution in biomass-burning plumes. We compare the effect of coagulation to that of OA evaporation and formation. We develop coagulation-only parameterizations for effective biomass-burning size distributions using the SAM-TOMAS large-eddy simulation plume model. For the most-sophisticated parameterization, we use the Gaussian Emulation Machine for Sensitivity Analysis (GEM-SA) to build a parameterization of the aged size distribution based on the SAM-TOMAS output and seven inputs: emission median dry diameter, emission distribution modal width, mass emissions flux, fire area, mean boundary-layer wind speed, plume mixing depth, and time/distance since emission. This parameterization was tested against an independent set of SAM-TOMAS simulations, and yields R2 values of 0.83 and 0.89 for Dpm and modal width, respectively. The aged size distribution is particularly sensitive to the mass emissions flux, fire area, wind speed, and time, and we provide simplified fits of the aged size distribution to just these input variables. These fits may be used in global and regional aerosol models. Finally, we show that variability in coagulation may lead to greater variability in the particle size distribution than does OA evaporation/formation using estimates of OA production/loss from the literature.

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

10.5194/amt-2021-59 ◽

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.

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On the formation of desert loess

Quaternary Research ◽

10.1017/qua.2020.33 ◽

2020 ◽

Vol 96 ◽

pp. 105-122 ◽

Cited By ~ 3

Author(s):

Nicholas Lancaster

Keyword(s):

Back Trajectory ◽

Main Process ◽

Coarse Silt ◽

Particle Collisions ◽

Sources And Sinks ◽

Back Trajectory Analysis ◽

Arid And Semiarid Areas ◽

Mechanical Weathering

AbstractSequences of quartz-rich coarse (20−63 μm) silt occur in many low- and midlatitude unglaciated arid and semiarid areas and have been termed “desert loess.” The processes by which these deposits are generated have been debated for decades. All hypotheses to explain their origin seek to provide mechanisms for the generation of silt-sized material without glacial grinding, which is the main process involved in the production of coarse silt at high latitudes. Possible mechanisms for the formation of coarse silt in arid regions include derivation from preexisting siltstones, mechanical weathering of silicate rocks, and abrasion of sand grains in active dune environments during intense transport events. Examination of the characteristics of desert loess and field and laboratory experiments to assess the role of dune areas as a source of coarse silt by abrasion and/or resuspension of residual fines suggests that many loess sequences are dominated by locally derived coarse silt. Improvements in the characterization of desert loess particle size, mineralogy, and geochemistry are needed, however, to identify sources and sinks of coarse silt, especially when combined with climatic back-trajectory analysis. Properly scaled experiments and modeling of particle collisions will also help to better quantify the effectiveness of abrasion in the generation of coarse silt in support of field observations.

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