scholarly journals Optical Properties of the Urban Aerosol Particles Obtained from Ground Based Measurements and Satellite-Based Modelling Studies

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Genrik Mordas ◽  
Nina Prokopciuk ◽  
Steigvilė Byčenkienė ◽  
Jelena Andriejauskienė ◽  
Vidmantas Ulevicius
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Urban Environment ◽  
Size Distribution ◽  
Number Concentration ◽  
Scattering Coefficient ◽  
Dust Particles ◽  
Aerosol Size Distribution ◽  
Air Masses ◽  
The Impact

Applications of satellite remote sensing data combined with ground measurements and model simulation were applied to study aerosol optical properties as well as aerosol long-range transport under the impact of large scale circulation in the urban environment in Lithuania (Vilnius). Measurements included the light scattering coefficients at 3 wavelengths (450, 550, and 700 nm) measured with an integrating nephelometer and aerosol particle size distribution (0.5–12 μm) and number concentration (Dpa> 0.5 μm) registered by aerodynamic particle sizer. Particle number concentration and mean light scattering coefficient varied from relatively low values of 6.0 cm−3and 12.8 Mm−1associated with air masses passed over Atlantic Ocean to relatively high value of 119 cm−3and 276 Mm−1associated with South-Western air masses. Analysis shows such increase in the aerosol light scattering coefficient (276 Mm−1) during the 3rd of July 2012 was attributed to a major Sahara dust storm. Aerosol size distribution with pronounced coarse particles dominance was attributed to the presence of dust particles, while resuspended dust within the urban environment was not observed.

scholarly journals Evaluating model parameterizations of submicron aerosol scattering and absorption with in situ data from ARCTAS 2008

2016 ◽  
Vol 16 (14) ◽  
pp. 9435-9455 ◽  
Author(s):  
Matthew J. Alvarado ◽  
Chantelle R. Lonsdale ◽  
Helen L. Macintyre ◽  
Huisheng Bian ◽  
Mian Chin ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Aerosol Size Distribution ◽  
Visible Radiation ◽  
Submicron Aerosol ◽  
In Situ Data ◽  
Aerosol Absorption ◽  
Aerosol Scattering ◽  
The Impact

Abstract. Accurate modeling of the scattering and absorption of ultraviolet and visible radiation by aerosols is essential for accurate simulations of atmospheric chemistry and climate. Closure studies using in situ measurements of aerosol scattering and absorption can be used to evaluate and improve models of aerosol optical properties without interference from model errors in aerosol emissions, transport, chemistry, or deposition rates. Here we evaluate the ability of four externally mixed, fixed size distribution parameterizations used in global models to simulate submicron aerosol scattering and absorption at three wavelengths using in situ data gathered during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. The four models are the NASA Global Modeling Initiative (GMI) Combo model, GEOS-Chem v9-02, the baseline configuration of a version of GEOS-Chem with online radiative transfer calculations (called GC-RT), and the Optical Properties of Aerosol and Clouds (OPAC v3.1) package. We also use the ARCTAS data to perform the first evaluation of the ability of the Aerosol Simulation Program (ASP v2.1) to simulate submicron aerosol scattering and absorption when in situ data on the aerosol size distribution are used, and examine the impact of different mixing rules for black carbon (BC) on the results. We find that the GMI model tends to overestimate submicron scattering and absorption at shorter wavelengths by 10–23 %, and that GMI has smaller absolute mean biases for submicron absorption than OPAC v3.1, GEOS-Chem v9-02, or GC-RT. However, the changes to the density and refractive index of BC in GC-RT improve the simulation of submicron aerosol absorption at all wavelengths relative to GEOS-Chem v9-02. Adding a variable size distribution, as in ASP v2.1, improves model performance for scattering but not for absorption, likely due to the assumption in ASP v2.1 that BC is present at a constant mass fraction throughout the aerosol size distribution. Using a core-shell mixing rule in ASP overestimates aerosol absorption, especially for the fresh biomass burning aerosol measured in ARCTAS-B, suggesting the need for modeling the time-varying mixing states of aerosols in future versions of ASP.

scholarly journals Evaluating Model Parameterizations of Submicron Aerosol Scattering and Absorption with In Situ Data from ARCTAS 2008

2016 ◽  
Author(s):  
M. J. Alvarado ◽  
C. R. Lonsdale ◽  
H. L. Macintyre ◽  
H. Bian ◽  
M. Chin ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Aerosol Size Distribution ◽  
Visible Radiation ◽  
Submicron Aerosol ◽  
In Situ Data ◽  
Aerosol Absorption ◽  
Aerosol Scattering ◽  
The Impact

Abstract. Accurate modeling of the scattering and absorption of ultraviolet and visible radiation by aerosols is essential for accurate simulations of atmospheric chemistry and climate. Closure studies using in situ measurements of aerosol scattering and absorption can be used to evaluate and improve models of aerosol optical properties without interference from model errors in aerosol emissions, transport, chemistry, or deposition rates. Here we evaluate the ability of four externally mixed, fixed size distribution parameterizations used in global models to simulate submicron aerosol scattering and absorption at three wavelengths using in situ data gathered during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. The four models are the NASA Global Modeling Initiative (GMI) Combo model, GEOS-Chem v9-02, the baseline configuration of a version of GEOS-Chem with online radiative transfer calculations (called GC-RT), and the Optical Properties of Aerosol and Clouds (OPAC v3.1) package. We also use the ARCTAS data to perform the first evaluation of the ability of the Aerosol Simulation Program (ASP v2.1) to simulate submicron aerosol scattering and absorption when in situ data on the aerosol size distribution is used, and examine the impact of different mixing rules for black carbon (BC) on the results. We find that the GMI model tends to overestimate submicron scattering and absorption at shorter wavelengths by 10–23 %, and that GMI has smaller absolute mean biases for submicron absorption than OPAC v3.1, GEOS-Chem v9-02, or GC-RT. However, the changes to the density and refractive index of BC in GC-RT improve the simulation of submicron aerosol absorption at all wavelengths relative to GEOS-Chem v9-02. Adding in situ size distribution information, as in ASP v2.1, improves model performance for scattering but not for absorption, likely due to the assumption in ASP v2.1 that BC is present at a constant mass fraction through out the aerosol size distribution. Using a core-shell mixing state in ASP overestimates aerosol absorption, especially for the fresh biomass burning aerosol measured in ARCTAS-B, suggesting the need for time-varying mixing states in future versions of ASP.

scholarly journals Evaluation of Second-Hand Exposure to Electronic Cigarette Vaping under a Real Scenario: Measurements of Ultrafine Particle Number Concentration and Size Distribution and Comparison with Traditional Tobacco Smoke

Toxics ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 59 ◽  
Author(s):  
Jolanda Palmisani ◽  
Alessia Di Gilio ◽  
Laura Palmieri ◽  
Carmelo Abenavoli ◽  
Marco Famele ◽  
...  
Keyword(s):  
Size Distribution ◽  
Tobacco Smoke ◽  
Ultrafine Particles ◽  
Natural Ventilation ◽  
Ultrafine Particle ◽  
Inhalation Exposure ◽  
Number Concentration ◽  
Aerosol Size Distribution ◽  
High Temporal Resolution ◽  
The Impact

The present study aims to evaluate the impact of e-cig second-hand aerosol on indoor air quality in terms of ultrafine particles (UFPs) and potential inhalation exposure levels of passive bystanders. E-cig second-hand aerosol characteristics in terms of UFPs number concentration and size distribution exhaled by two volunteers vaping 15 different e-liquids inside a 49 m3 room and comparison with tobacco smoke are discussed. High temporal resolution measurements were performed under natural ventilation conditions to simulate a realistic exposure scenario. Results showed a systematic increase in UFPs number concentration (part cm−3) related to a 20-min vaping session (from 6.56 × 103 to 4.01 × 104 part cm−3), although this was one up to two order of magnitude lower than that produced by one tobacco cigarette consumption (from 1.12 × 105 to 1.46 × 105 part cm−3). E-cig second-hand aerosol size distribution exhibits a bimodal behavior with modes at 10.8 and 29.4 nm in contrast with the unimodal typical size distribution of tobacco smoke with peak mode at 100 nm. In the size range 6–26 nm, particles concentration in e-cig second-hand aerosol were from 2- (Dp = 25.5 nm) to 3800-fold (Dp = 9.31 nm) higher than in tobacco smoke highlighting that particles exhaled by users and potentially inhaled by bystanders are nano-sized with high penetration capacity into human airways.

scholarly journals Observations of aerosol optical properties at a coastal site in Hong Kong, South China

2017 ◽  
Vol 17 (4) ◽  
pp. 2653-2671 ◽  
Author(s):  
Jiaping Wang ◽  
Aki Virkkula ◽  
Yuan Gao ◽  
Shuncheng Lee ◽  
Yicheng Shen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Hong Kong ◽  
Light Scattering ◽  
South China ◽  
Eastern China ◽  
Light Extinction ◽  
Aerosol Optical Properties ◽  
Air Masses ◽  
Rural Sites ◽  
The Impact

Abstract. Temporal variations in aerosol optical properties were investigated at a coastal station in Hong Kong based on the field observation from February 2012 to February 2015. At 550 nm, the average light-scattering (151 ± 100 Mm−1) and absorption coefficients (8.3 ± 6.1 Mm−1) were lower than most of other rural sites in eastern China, while the single-scattering albedo (SSA  =  0.93 ± 0.05) was relatively higher compared with other rural sites in the Pearl River Delta (PRD) region. Correlation analysis confirmed that the darkest aerosols were smaller in particle size and showed strong scattering wavelength dependencies, indicating possible sources from fresh emissions close to the measurement site. Particles with Dp of 200–800 nm were less in number, yet contributed the most to the light-scattering coefficients among submicron particles. In summer, both ΔBC / ΔCO and SO2 / BC peaked, indicating the impact of nearby combustion sources on this site. Multi-year backward Lagrangian particle dispersion modeling (LPDM) and potential source contribution (PSC) analysis revealed that these particles were mainly from the air masses that moved southward over Shenzhen and urban Hong Kong and the polluted marine air containing ship exhausts. These fresh emission sources led to low SSA during summer months. For winter and autumn months, contrarily, ΔBC / ΔCO and SO2 / BC were relatively low, showing that the site was more under influence of well-mixed air masses from long-range transport including from South China, East China coastal regions, and aged aerosol transported over the Pacific Ocean and Taiwan, causing stronger abilities of light extinction and larger variability of aerosol optical properties. Our results showed that ship emissions in the vicinity of Hong Kong could have visible impact on the light-scattering and absorption abilities as well as SSA at Hok Tsui.

scholarly journals The role of the particle size distribution in assessing aerosol composition effects on simulated droplet activation

2010 ◽  
Vol 10 (2) ◽  
pp. 4189-4223 ◽  
Author(s):  
D. S. Ward ◽  
T. Eidhammer ◽  
W. R. Cotton ◽  
S. M. Kreidenweis
Keyword(s):  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Atmospheric Modeling ◽  
Number Concentration ◽  
Aerosol Size Distribution ◽  
Detailed Knowledge ◽  
Aerosol Composition ◽  
Droplet Activation ◽  
The Impact ◽  
Aerosol Hygroscopicity

Abstract. Variations in the chemical composition of atmospheric aerosols alter their hygroscopicity and can lead to changes in the cloud-active fraction of the aerosols, or cloud condensation nuclei (CCN) number concentration. To investigate the importance of this effect under different atmospheric conditions, cloud droplet formation was simulated with a Lagrangian parcel model. Initial values of updraft speed and temperature were systematically varied along with aerosol number concentration, size and hygroscopicity (represented by the hygroscopicity parameter, κ). A previous study classifies the sensitivity of CCN activity to compositional changes based on the supersaturation reached in the parcel model. We found that these classifications could not be generalized to a range of aerosol size distribution median radii. Instead, variations in sensitivity with size depend on the location of the dry critical radius for droplet activation relative to the size distribution median radius. The parcel model output was used to construct droplet activation lookup tables based on κ that were implemented in the Regional Atmospheric Modeling System (RAMS) microphysical scheme. As a first application of this system, aerosol hygroscopicity and size were varied in a series of RAMS mesoscale simulations designed to investigate the sensitivity of a mixed-phase orographic cloud case to the parameter variations. Observations from a recent field campaign in northwestern Colorado provided the basis for the aerosol field initializations. Model results show moderate sensitivity in the distribution of total case precipitation to extreme changes in κ, and minimal sensitivity to observed changes in estimated κ. The impact of varying aerosol hygroscopicity diminished with increasing median radius, as expected from the parcel model results. The conclusions drawn from these simulations could simplify similar research in other cloud regimes by defining the need, or lack of need, for detailed knowledge of aerosol composition.

scholarly journals Observations of aerosol optical properties at a coastal site in Hong Kong, South China

2016 ◽  
Author(s):  
Jiaping Wang ◽  
Aki Virkkula ◽  
Yuan Gao ◽  
Shuncheng Lee ◽  
Yicheng Shen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Hong Kong ◽  
Light Scattering ◽  
South China ◽  
Eastern China ◽  
Light Extinction ◽  
Aerosol Optical Properties ◽  
Air Masses ◽  
Rural Sites ◽  
The Impact

Abstract. Temporal variations of aerosol optical properties were investigated at a coastal station in Hong Kong based on the field observation from February 2012 to February 2015. At 550 nm, the average light scattering (150.6 Mm−1) and absorption coefficient (8.3 Mm−1) were lower than most of other rural sites in eastern China while the single scattering albedo (SSA = 0.93 ± 0.05) was relatively higher compared with other rural sites in the Pearl River Delta (PRD) region. Correlation analysis showed that the darkest aerosols were smaller in particle size but showed strong scattering wavelength dependencies, indicating possible sources from fresh emissions close to the measurement site. Particles with Dp of 200–800 nm were less in number, yet contributed the most to the light scattering coefficients among submicron particles. In summer, both ΔBC/ΔCO and SO2/BC peaked, indicating the impact of nearby combustion sources on this site. Multi-year backward LPDM and PSC analysis revealed that these particles were mainly from the air masses moved southward over Shenzhen and urban Hong Kong and the polluted marine air containing ship exhausts. These fresh emission sources led to low SSA during summer. For winter and autumn months, contrarily, ΔBC/ΔCO and SO2/BC were relatively low, showing that the site was more under influence of well-mixed air masses from long-range transport including South China, East China coastal regions, and aged aerosol transported over Pacific Ocean and Taiwan Island, causing stronger abilities of light extinction and larger variability of aerosol optical properties. Our results showed that ship emissions in the vicinity of Hong Kong could have visible impact on the light scattering and absorption abilities as well as SSA at Hok Tsui.

scholarly journals Evaluating the PurpleAir monitor as an aerosol light scattering instrument

2021 ◽  
Author(s):  
James R. Ouimette ◽  
William C. Malm ◽  
Bret A. Schichtel ◽  
Patrick J. Sheridan ◽  
Elisabeth Andrews ◽  
...  
Keyword(s):  
Particle Size ◽  
Light Scattering ◽  
Size Distribution ◽  
Field Data ◽  
Scattered Light ◽  
Concentration Field ◽  
Scattering Coefficient ◽  
Coefficient Of Determination ◽  
Aerosol Size Distribution ◽  
Aerosol Mass Concentration

Abstract. The Plantower PMS5003 sensors (PA-PMS) used in the PurpleAir (PA) monitor PA-II-SD configuration are equivalent to cell-reciprocal nephelometers using a 657 nm perpendicularly polarized light source that integrates light scattering from 18 to 166 degrees. Yearlong field data at the National Oceanic and Atmospheric Administration’s (NOAA) Mauna Loa Observatory (MLO) and Boulder Table Mountain (BOS) sites show that the 1 h average of the PA-PMS first size channel, labeled “> 0.3 μm” (“CH1”) is highly correlated with submicrometer aerosol scattering coefficients at the 550 nm and 700 nm wavelengths measured by the TSI 3563 integrating nephelometer, from 0.4 Mm−1 to 500 Mm−1. This corresponds to an hourly average submicrometer aerosol mass concentration of approximately 0.2 to 200 ug m−3. A physical-optical model of the PA-PMS is developed to estimate light intensity on the photodiode, accounting for angular truncation as a function of particle size. Predictions are then compared with yearlong fine aerosol size distribution and scattering coefficient field data at the BOS site. It is shown that CH1 is linearly proportional to the model-predicted intensity of the light scattered by particles in the PA-PMS laser to its photodiode over 4 orders of magnitude. This is consistent with CH1 being a measure of the scattering coefficient and not the particle number concentration or particulate matter concentration. Field data at BOS confirm the model prediction that the ratio of CH1 to the scattering coefficient would be highest for aerosols with median scattering diameters < 0.3 μm. The PA-PMS detects aerosols smaller than 0.3 μm diameter in proportion to their contribution to the scattering coefficient. The model predicts that the PA-PMS response to particles > 0.3 μm decreases relative to an ideal nephelometer by about 75 % for particle diameters ≥ 1.0 μm. This is a result of using a laser that is polarized, the angular truncation of the scattered light, and particle loss in the instrument before reaching the laser. The results of this study indicate that the PA-PMS is not an optical particle counter and that its six size fractions are not an accurate representation of particle size distribution. The relationship between the PA-PMS 1 h average CH1 and bsp1, the scattering coefficient in Mm−1 due to particles below 1 μm aerodynamic diameter, at wavelength 550 nanometers, is found to be bsp1 = 0.015 ± 2.07 × 10−5 × CH1, for relative humidity below 40 %. The coefficient of determination R2 is 0.97. This suggests that the low-cost and widely used PA monitors can be used to measure and predict the aerosol light scattering coefficient in the mid-visible nearly as well as integrating nephelometers.

scholarly journals The role of the particle size distribution in assessing aerosol composition effects on simulated droplet activation

2010 ◽  
Vol 10 (12) ◽  
pp. 5435-5447 ◽  
Author(s):  
D. S. Ward ◽  
T. Eidhammer ◽  
W. R. Cotton ◽  
S. M. Kreidenweis
Keyword(s):  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Atmospheric Modeling ◽  
Number Concentration ◽  
Aerosol Size Distribution ◽  
Detailed Knowledge ◽  
Aerosol Composition ◽  
Droplet Activation ◽  
The Impact ◽  
Aerosol Hygroscopicity

Abstract. Variations in the chemical composition of atmospheric aerosols alter their hygroscopicity and can lead to changes in the cloud-active fraction of the aerosols, or cloud condensation nuclei (CCN) number concentration. To investigate the importance of this effect under different atmospheric conditions, cloud droplet formation was simulated with a Lagrangian parcel model. Initial values of updraft speed and temperature were systematically varied along with aerosol number concentration, size and hygroscopicity (represented by the hygroscopicity parameter, κ). A previous study classifies the sensitivity of CCN activity to compositional changes based on the supersaturation reached in the parcel model. We found that these classifications could not be generalized to a range of aerosol size distribution median radii. Instead, variations in sensitivity with size depend on the location of the dry critical radius for droplet activation relative to the size distribution median radius. The parcel model output was used to construct droplet activation lookup tables based on κ that were implemented in the Regional Atmospheric Modeling System (RAMS) microphysical scheme. As a first application of this system, aerosol hygroscopicity and size were varied in a series of RAMS mesoscale simulations designed to investigate the sensitivity of a mixed-phase orographic cloud case to the parameter variations. Observations from a recent field campaign in northwestern Colorado provided the basis for the aerosol field initializations. Model results show moderate sensitivity in the distribution of total case precipitation to extreme changes in κ, and minimal sensitivity to observed changes in estimated κ. The impact of varying aerosol hygroscopicity diminished with increasing median radius, as expected from the parcel model results. The conclusions drawn from these simulations could simplify similar research in other cloud regimes by defining the need, or lack of need, for detailed knowledge of aerosol composition.

scholarly journals Characteristics of regional new particle formation in urban and regional background environments in the North China Plain

2013 ◽  
Vol 13 (8) ◽  
pp. 20531-20560 ◽  
Author(s):  
Z. B. Wang ◽  
M. Hu ◽  
J. Y. Sun ◽  
Z. J. Wu ◽  
D. L. Yue ◽  
...  
Keyword(s):  
Light Scattering ◽  
Urban Environment ◽  
North China Plain ◽  
North China ◽  
Particle Formation ◽  
Number Concentration ◽  
Scattering Coefficient ◽  
New Particle Formation ◽  
The North ◽  
The North China Plain

Abstract. Long-term measurements of particle number size distributions were carried out in the North China Plain both at an urban background site (Peking University, PKU) and a regional Global Atmospheric Watch station (Shangdianzi, SDZ) from March to November in 2008. In total, 52 new particle formation events were observed simultaneously at both sites, indicating that this is a regional phenomenon in the North China Plain. On average, the mean condensation sink value before the nucleation event start was 0.025 s−1 in the urban environment, which was 1.6 times higher than that at regional site. However, higher particle formation and growth rates were observed at PKU (10.8 cm−3 s−1 an 5.2 nm h−1) compared with those at SDZ (4.9 cm−3 s−1 and 4.0 nm h−1). These results implied that more precursors are needed to participate in the nucleation process to observe the occurrence of new particle formation event in a more polluted urban environment. Different from the observations in clean environments, the background condition of the observed nucleation events in the North China Plain could be characterized as the co-existing of the higher source and sink. The condensational growth of newly formed particles results in an increase in the particle mass concentration, particle light scattering coefficient, and CCN number concentration, with consequences on climate effects and air quality. In 34 investigated new particle formation cases at both sites, a significant particle nucleation and subsequent growth over a sufficient long time period were observed and investigated in terms of the particle light scattering and the number concentration of "potential" CCN. The results revealed that the new particle formation increases the particle light scattering coefficient and CCN number concentration in the North China Plain by factors in the range of 6.3–7.6 and 5.6–8.7, respectively. Moreover, the potential contribution of anthropogenic emissions to the CCN number concentration is more than 50%, which should be drawn more attentions in the regional and global climate model, especially in the polluted urban areas.

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