Analysis of correlations between scattering coefficient of submicron aerosol and mass concentration of soot according to airborne measurements in 2000–2018

Abstract. The vertical distribution in the physical and chemical properties of submicron aerosol has been characterised across northern India for the first time using airborne in-situ measurements. This study focusses primarily on the Indo-Gangetic Plain, a low-lying area in the north of India which commonly experiences high aerosol mass concentrations prior to the monsoon season. Data presented are from the UK Facility for Airborne Atmospheric Measurements BAe-146 research aircraft that performed flights in the region during the 2016 pre-monsoon (11th and 12th June) and monsoon (30th June to 11th July) seasons. Inside the Indo-Gangetic Plain boundary layer, organic matter dominated the submicron aerosol mass (43&thinsp;%) followed by sulphate (29&thinsp;%), ammonium (14&thinsp;%), nitrate (7&thinsp;%) and black carbon (7&thinsp;%). However, outside the Indo-Gangetic Plain, sulphate was the dominant species contributing 44&thinsp;% to the total submicron aerosol mass in the boundary layer, followed by organic matter (30&thinsp;%), ammonium (14&thinsp;%), nitrate (6&thinsp;%) and black carbon (6&thinsp;%). Chlorine mass concentrations were negligible throughout the campaign. Black carbon mass concentrations were higher inside the Indo-Gangetic Plain (2&thinsp;µg/m3 std) compared to outside (1&thinsp;µg/m3 std). Nitrate appeared to be controlled by thermodynamic processes, with increased mass concentration in conditions of lower temperature and higher relative humidity. Increased mass and number concentrations were observed inside the Indo-Gangetic Plain and the aerosol was more absorbing in this region, whereas outside the Indo-Gangetic Plain the aerosol was larger in size and more scattering in nature, suggesting greater dust presence especially in northwest India. The aerosol composition remained largely similar as the monsoon season progressed, but the total aerosol mass concentrations decreased by ~&thinsp;50&thinsp;% as the rainfall arrived; the pre-monsoon average total mass concentration was 30&thinsp;µg/m3 std compared to a monsoon average total mass concentration of 10&ndash;20&thinsp;µg/m3 std. However, this mass concentration decrease was less noteworthy (~&thinsp;20&ndash;30&thinsp;%) over the Indo-Gangetic Plain, likely due to the strength of emission sources in this region. Decreases occurred in coarse mode aerosol, with the fine mode fraction increasing with monsoon arrival. In the aerosol vertical profile, inside the Indo-Gangetic Plain during the pre-monsoon, organic aerosol and absorbing aerosol species dominated in the lower atmosphere (<&thinsp;1.5&thinsp;km) with sulphate, dust and other scattering aerosol species enhanced in an elevated aerosol layer above 1.5&thinsp;km with maximum aerosol height ~&thinsp;6&thinsp;km. As the monsoon progressed into this region, the elevated aerosol layer diminished, the aerosol maximum height reduced to ~&thinsp;2&thinsp;km and the total mass concentrations decreased by ~&thinsp;50&thinsp;%. The dust and sulphate-dominated aerosol layer aloft was removed upon monsoon arrival, highlighted by an increase in fine mode fraction throughout the profile.

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Airborne observations of the Eyjafjalla volcano ash cloud over Europe during air space closure in April and May 2010

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-22131-2010 ◽

2010 ◽

Vol 10 (9) ◽

pp. 22131-22218 ◽

Cited By ~ 24

Author(s):

U. Schumann ◽

B. Weinzierl ◽

O. Reitebuch ◽

H. Schlager ◽

A. Minikin ◽

...

Keyword(s):

Mass Flux ◽

Mass Concentration ◽

Volcanic Ash ◽

Mixing Ratio ◽

Airborne Measurements ◽

Particle Properties ◽

Mixing Ratios ◽

Coarse Mode ◽

Space Closure ◽

Ash Cloud

Abstract. Airborne measurements of Lidar backscatter, aerosol concentrations (particle diameters of 4 nm to 50 μm), trace gas mixing ratios (SO2, CO, O3, H2O), single particle properties, and meteorological parameters have been performed in volcanic ash plumes with the Falcon aircraft operated by Deutsches Zentrum für Luft- und Raumfahrt (DLR). A series of 17 flights was performed over Europe between Southern Germany and Iceland during the eruption period of the Eyjafjalla1 volcano between 19 April and 18 May 2010. Flight planning and measurement analyses were supported by a refined Meteosat ash product and trajectory model analysis. The volcanic ash plume was observed with Lidar directly over the volcano and up to a distance of 2700 km downwind. Lidar and in-situ measurements covered plume ages of 7 h to 120 h. Aged ash layers were between a few 100 m to 3 km deep, occurred between 1 and 7 km altitude, and were typically 100 to 300 km wide. Particles collected by impactors had diameters up to 20 μm diameter, with size and age dependent composition. Ash mass concentration was evaluated for a material density of 2.6 g cm−3 and for either weakly or moderately absorbing coarse mode particles (refractive index 1.59+0i or 1.59+0.004i). In the absorbing case, the ash concentration is about a factor of four larger than in the non-absorbing limit. Because of sedimentation constraints, the smaller results are the more realistic ones for aged plumes. The Falcon flew in ash clouds up to about 1 mg m−3 for a few minutes and in an ash cloud with more than 0.2 mg m−3 mean-concentration for about one hour without engine damages. In fresh plumes, the SO2 concentration was correlated with the ash mass concentration. Typically, 0.5 mg m−3 ash concentration was related to about 100 nmol mol−31 SO2 mixing ratio and 70 nmol mol−1 CO mixing ratio increases for this volcano period. In aged plumes, layers with enhanced coarse mode particle concentration but without SO2 enhancements occurred. To first order, ash concentration and SO2 mixing ratio in the plumes decreased by a factor of two within less than a day. The ash plumes were often visible as faint dark layers even for concentrations below 0.1 mg m−3. The ozone concentrations and the humidity inside the plumes were often reduced compared to ambient values. The large abundance of volatile Aitken mode particles suggests nucleation of sulfuric acid droplets. Ammonium sulfate particles were also found on the impactors. The effective diameters decreased from about 5 μm in the fresh plume to about 1 μm for plume ages of up to 6 days. The distal ash mass flux on 2 May was of the order 1800 kg s−1; the SO2 mass flux was about a factor of 3–4 smaller. The volcano ejected about 40 Tg of ash mass and 10 Tg of SO2 during the whole eruption period. The results of the Falcon flights were used to support the responsible agencies in their decisions concerning air traffic in the presence of volcanic ash. The data described may be used for further studies, including comparisons to satellite and ground or space based Lidar observations, and for model improvements. 1 Also known as Eyjafjallajökull or Eyjafjöll volcano, http://www.britannica.com/EBchecked/topic/1683937/Eyjafjallajokull-volcano

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Evaluation of Two Low-Cost Optical Particle Counters for the Measurement of Ambient Aerosol Scattering Coefficient and Ångström Exponent

Sensors ◽

10.3390/s20092617 ◽

2020 ◽

Vol 20 (9) ◽

pp. 2617 ◽

Cited By ~ 4

Author(s):

Krzysztof M. Markowicz ◽

Michał T. Chiliński

Keyword(s):

Optical Properties ◽

Correlation Coefficient ◽

Mass Concentration ◽

Low Cost ◽

Pearson Correlation ◽

Scattering Coefficient ◽

Pearson Correlation Coefficient ◽

Aerosol Optical Properties ◽

Aerosol Scattering ◽

Ångström Exponent

The aerosol scattering coefficient and Ångström exponent (AE) are important parameters in the understanding of aerosol optical properties and aerosol direct effect. These parameters are usually measured by a nephelometer network which is under-represented geographically; however, a rapid growth of air-pollution monitoring, using low-cost particle sensors, may extend observation networks. This paper presents the results of co-located measurements of aerosol optical properties, such as the aerosol scattering coefficient and the scattering AE, using low-cost sensors and using a scientific-grade polar Aurora 4000 nephelometer. A high Pearson correlation coefficient (0.94–0.96) between the low-cost particulate matter (PM) mass concentration and the aerosol scattering coefficient was found. For the PM10 mass concentration, the aerosol scattering coefficient relation is linear for the Dfrobot SEN0177 sensor and non-linear for the Alphasense OPC-N2 device. After regression analyses, both low-cost instruments provided the aerosol scattering coefficient with a similar mean square error difference (RMSE) of about 20 Mm−1, which corresponds to about 27% of the mean aerosol scattering coefficient. The relative uncertainty is independent of the pollution level. In addition, the ratio of aerosol number concentration between different bins showed a significant statistical (95% of confidence level) correlation with the scattering AE. For the SEN0177, the ratio of the particle number in bin 1 (radius of 0.15–0.25 µm) to bin 4 (radius of 1.25–2.5 µm) was a linear function of the scattering AE, with a Pearson correlation coefficient of 0.74. In the case of OPC-N2, the best correlation (r = 0.66) was found for the ratio between bin 1 (radius of 0.19–0.27 µm) and bin 2 (radius of 0.27–0.39 µm). Comparisons of an estimated scattering AE from a low-cost sensor with Aurora 4000 are given with the RMSE of 0.23–0.24, which corresponds to 16–19%. In addition, a three-year (2016–2019) observation by SEN0177 indicates that this sensor can be used to determine an annual cycle as well as a short-term variability.

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Atmospheric aerosol scattering to mass ratio

Canadian Journal of Physics ◽

10.1139/p80-077 ◽

1980 ◽

Vol 58 (4) ◽

pp. 549-553

Author(s):

A. W. Harrison ◽

Rosaline Pi

Keyword(s):

Atmospheric Aerosol ◽

Mass Concentration ◽

Cascade Impactor ◽

Scattering Coefficient ◽

Mass Ratio ◽

Aerosol Scattering ◽

Combined Operation ◽

Mass Size ◽

Clean Air ◽

Made In

The combined operation of a spectronephelometer and a cascade impactor has been used to study the ratio of differential scattering coefficient (at 550 nm) and mass concentration at mass concentrations of less than 40 µg m−3. Detailed analysis of the mass size distribution impactor data assumed to be near lognormal yielded values of the bulk density in the range 1 to 4 g cm−3. Measurements made in May–June 1978 and in November–December 1978 gave substantially the same results indicating no seasonal variation in either aerosol density or scattering coefficient to mass concentration ratio for mountain and continental background clean air.

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Source attribution of climatically important aerosol properties measured at Paposo (Chile) during VOCALS

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-10789-2010 ◽

2010 ◽

Vol 10 (22) ◽

pp. 10789-10801 ◽

Cited By ~ 30

Author(s):

D. Chand ◽

D. A. Hegg ◽

R. Wood ◽

G. E. Shaw ◽

D. Wallace ◽

...

Keyword(s):

Light Scattering ◽

Size Distribution ◽

Biomass Burning ◽

Receptor Modeling ◽

Scattering Coefficient ◽

Source Attribution ◽

Aerosol Composition ◽

Submicron Aerosol ◽

Aerosol Mass ◽

Aerosol Mass Concentration

Abstract. Measurements of submicron aerosol composition, light scattering, and size distribution were made from 17 October to 15 November 2008 at the elevated Paposo site (25° 0.4' S, 70° 27.01' W, 690 m a.s.l.) on the Chilean coast as part of the VOCALS* Regional Experiment (REx). Based on the chemical composition measurements, a receptor modeling analysis using Positive Matrix Factorization (PMF) was carried out, yielding four broad source categories of the aerosol mass, light scattering coefficient, and a proxy for cloud condensation nucleus (CCN) concentration at 0.4% supersaturation derived from the size distribution measurements assuming an observed soluble mass fraction of 0.53. The sources resolved were biomass burning, marine, an urban-biofuels mix and a somewhat ambiguous mix of smelter emissions and mineral dust. The urban-biofuels mix is the most dominant aerosol mass component (52%) followed by biomass burning (25%), smelter/soil dust (12%) and marine (9%) sources. The average (mean±std) submicron aerosol mass concentration, aerosol light scattering coefficient and proxy CCN concentration were, 8.77±5.40 μg m−3, 21.9±11.0 Mm−1 and 548±210 cm−3, respectively. Sulfate is the dominant identified submicron species constituting roughly 40% of the dry mass (3.64±2.30 μg m−3), although the indentified soluble species constitute only 53% of the mass. Much of the unidentified mass is likely organic in nature. The relative importance of each aerosol source category is different depending upon whether mass, light scattering, or CCN concentration is being considered, indicating that the mean size of aerosols associated with each source are different. Marine aerosols do not appear to contribute to more than 10% to either mass, light scattering, or CCN concentration at this site. Back trajectory cluster analysis proved consistent with the PMF source attribution. *VOCALS: VAMOS** Ocean-Cloud-Atmosphere-Land Study (VOCALS) **VAMOS: Variability of American Monsoon System

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Source attribution of climatically important aerosol properties measured at Paposo (Chile) during VOCALS

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-17853-2010 ◽

2010 ◽

Vol 10 (7) ◽

pp. 17853-17887 ◽

Cited By ~ 1

Author(s):

D. Chand ◽

D. A. Hegg ◽

R. Wood ◽

G. E. Shaw ◽

D. Wallace ◽

...

Keyword(s):

Light Scattering ◽

Size Distribution ◽

Biomass Burning ◽

Receptor Modeling ◽

Scattering Coefficient ◽

Source Attribution ◽

Aerosol Composition ◽

Submicron Aerosol ◽

Aerosol Mass ◽

Aerosol Mass Concentration

Abstract. Measurements of submicron aerosol composition, light scattering, and size distribution were made from 17 October to 15 November 2008 at the elevated Paposo site (25° 0.4' S, 70°27.01' W, 690 m a.s.l.) on the Chilean coast as part of the VOCALS1 Regional Experiment (REx). Based on the chemical composition measurements, a receptor modeling analysis using Positive Matrix Factorization (PMF) was carried out, yielding four broad source categories of the aerosol mass, light scattering coefficient, and a proxy for cloud condensation nucleus (CCN) concentration at 0.4% supersaturation derived from the size distribution measurements assuming an observed soluble mass fraction of 0.53. The sources resolved were biomass burning, marine, an urban-biofuels mix and a somewhat ambiguous mix of smelter emissions and mineral dust. The urban-biofuels mix is the most dominant aerosol mass component (52%) followed by biomass burning (25%), smelter/soil dust (12%) and marine (9%) sources. The average (mean±std) submicron aerosol mass concentration, aerosol light scattering coefficient and proxy CCN concentration were, 8.77±5.40 μg m−3, 21.9±11.0 Mm−1 and 548±210 cm−3, respectively. Sulfate is the dominant identified submicron species constituting roughly 40% of the dry mass (3.64±2.30 μg m−3, although the indentified soluble species constitute only 53% of the mass. Much of the unidentified mass is likely organic in nature. The relative importance of each aerosol source category is different depending upon whether mass, light scattering, or CCN concentration is being considered, indicating that the mean size of aerosols associated with each source are different. Marine aerosols do not appear to contribute to more than 10% to either mass, light scattering, or CCN concentration at this site. Back trajectory cluster analysis proved consistent with the PMF source attribution. 1 VOCALS: VAMOS Ocean-Cloud-Atmosphere-Land Study (VOCALS)VAMOS: Variability of American Monsoon System

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The Scattering Coefficient and Mass Concentration of Smoke from Some Australian Forest Fires

Journal of the Air Pollution Control Association ◽

10.1080/00022470.1974.10470011 ◽

1974 ◽

Vol 24 (11) ◽

pp. 1047-1050 ◽

Cited By ~ 2

Author(s):

A.J. Eccleston ◽

N.K. King ◽

D.R. Packham

Keyword(s):

Forest Fires ◽

Mass Concentration ◽

Scattering Coefficient

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Vertical and horizontal distribution of submicron aerosol chemical composition and physical characteristics across northern India during pre-monsoon and monsoon seasons

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-5615-2019 ◽

2019 ◽

Vol 19 (8) ◽

pp. 5615-5634 ◽

Cited By ~ 19

Author(s):

James Brooks ◽

James D. Allan ◽

Paul I. Williams ◽

Dantong Liu ◽

Cathryn Fox ◽

...

Keyword(s):

Black Carbon ◽

Mass Concentration ◽

Monsoon Season ◽

Western India ◽

Aerosol Layer ◽

Gangetic Plain ◽

Submicron Aerosol ◽

Aerosol Mass ◽

Indo Gangetic Plain ◽

Mass Concentrations

Abstract. The vertical distribution in the physical and chemical properties of submicron aerosol has been characterised across northern India for the first time using airborne in situ measurements. This study focusses primarily on the Indo-Gangetic Plain, a low-lying area in the north of India which commonly experiences high aerosol mass concentrations prior to the monsoon season. Data presented are from the UK Facility for Airborne Atmospheric Measurements BAe-146 research aircraft that performed flights in the region during the 2016 pre-monsoon (11 and 12 June) and monsoon (30 June to 11 July) seasons. Inside the Indo-Gangetic Plain boundary layer, organic matter dominated the submicron aerosol mass (43&thinsp;%) followed by sulfate (29&thinsp;%), ammonium (14&thinsp;%), nitrate (7&thinsp;%) and black carbon (7&thinsp;%). However, outside the Indo-Gangetic Plain, sulfate was the dominant species, contributing 44&thinsp;% to the total submicron aerosol mass in the boundary layer, followed by organic matter (30&thinsp;%), ammonium (14&thinsp;%), nitrate (6&thinsp;%) and black carbon (6&thinsp;%). Chlorine mass concentrations were negligible throughout the campaign. Black carbon mass concentrations were higher inside the Indo-Gangetic Plain (2&thinsp;µg&thinsp;m−3) compared to outside (1&thinsp;µg&thinsp;m−3). Nitrate appeared to be controlled by thermodynamic processes, with increased mass concentration in conditions of lower temperature and higher relative humidity. Increased mass and number concentrations were observed inside the Indo-Gangetic Plain and the aerosol was more absorbing in this region, whereas outside the Indo-Gangetic Plain the aerosol was larger in size and more scattered in nature, suggesting greater dust presence, especially in north-western India. The aerosol composition remained largely similar as the monsoon season progressed, but the total aerosol mass concentrations decreased by ∼50&thinsp;% as the rainfall arrived; the pre-monsoon average total mass concentration was 30&thinsp;µg&thinsp;m−3 compared to a monsoon average total mass concentration of 10–20&thinsp;µg&thinsp;m−3. However, this mass concentration decrease was less noteworthy (∼20&thinsp;%–30&thinsp;%) over the Indo-Gangetic Plain, likely due to the strength of emission sources in this region. Decreases occurred in coarse mode aerosol, with the fine mode fraction increasing with monsoon arrival. In the aerosol vertical profile, inside the Indo-Gangetic Plain during the pre-monsoon, organic aerosol and absorbing aerosol species dominated in the lower atmosphere (&lt;1.5&thinsp;km), with sulfate, dust and other scattering aerosol species enhanced in an elevated aerosol layer above 1.5&thinsp;km with maximum aerosol height ∼6&thinsp;km. The elevated concentration of dust at altitudes &gt;1.5&thinsp;km is a clear indication of dust transport from the Great Indian Desert, also called the Thar Desert, in north-western India. As the monsoon progressed into this region, the elevated aerosol layer diminished, the aerosol maximum height reduced to ∼2&thinsp;km. The dust and sulfate-dominated aerosol layer aloft was removed upon monsoon arrival, highlighted by an increase in fine mode fraction throughout the profile.

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