A new airborne aerosol sampling system: development, validation, and application in vertical measurement of black carbon mixing state

2021 ◽  
Author(s):  
Shaowen Zhu ◽  
Nan Ma ◽  
Linhong Xie ◽  
Nan Lu ◽  
Minglu Li ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Black Carbon ◽  
System Development ◽  
Chemical Properties ◽  
Aerosol Sampling ◽  
Tethered Balloon ◽  
Mixing State ◽  
Sampling System ◽  
Aerosol Mass ◽  
Aerial Vehicle

<p>Vertical measurements of aerosol physical-chemical properties have important significance for better addressing the environment and climate effects of atmospheric aerosol. Traditional in-situ vertical observations of those properties are mainly based on aircraft platforms which are costly and restrictive, and not applicable for near-ground (<500 m) measurements. Within the boundary layer, tethered balloon and unmanned aerial vehicle (UAV) are ideal observation platforms but cannot carry heavy online aerosol instruments due to payload limitations. In this study, a new lightweight airborne aerosol sampling system is developed for tethered balloon and UAV platform. The system can collect airborne aerosol samples at up to 12 heights with conductive bags, and the samples can be analyzed later by online instruments such as aerosol mass spectrometer and single particle soot photometer (SP2). During an intensive field campaign conducted in Lhasa in summer of 2020, the new developed system was applied together with a SP2 to determine the vertical profile of refractory black carbon (rBC) mixing state. Preliminary results show that most rBC containing particles are external mixture and the proportion of internally mixed rBC increases with height. The vertical profiles of rBC mixing state are affected by surface emissions, the development of atmospheric boundary layer and meteorological conditions.</p>

scholarly journals Quantification of black carbon mixing state from traffic: implications for aerosol optical properties

2016 ◽  
Vol 16 (7) ◽  
pp. 4693-4706 ◽  
Author(s):  
Megan D. Willis ◽  
Robert M. Healy ◽  
Nicole Riemer ◽  
Matthew West ◽  
Jon M. Wang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Black Carbon ◽  
Chemical Properties ◽  
Mixing State ◽  
Aerosol Optical Properties ◽  
Aerosol Composition ◽  
Average Mass ◽  
Measurement Capability ◽  
Aerosol Mass ◽  
Physical And Chemical

Abstract. The climatic impacts of black carbon (BC) aerosol, an important absorber of solar radiation in the atmosphere, remain poorly constrained and are intimately related to its particle-scale physical and chemical properties. Using particle-resolved modelling informed by quantitative measurements from a soot-particle aerosol mass spectrometer, we confirm that the mixing state (the distribution of co-emitted aerosol amongst fresh BC-containing particles) at the time of emission significantly affects BC-aerosol optical properties even after a day of atmospheric processing. Both single particle and ensemble aerosol mass spectrometry observations indicate that BC near the point of emission co-exists with hydrocarbon-like organic aerosol (HOA) in two distinct particle types: HOA-rich and BC-rich particles. The average mass fraction of black carbon in HOA-rich and BC-rich particle classes was  < 0.1 and 0.8, respectively. Notably, approximately 90 % of BC mass resides in BC-rich particles. This new measurement capability provides quantitative insight into the physical and chemical nature of BC-containing particles and is used to drive a particle-resolved aerosol box model. Significant differences in calculated single scattering albedo (an increase of 0.1) arise from accurate treatment of initial particle mixing state as compared to the assumption of uniform aerosol composition at the point of BC injection into the atmosphere.

scholarly journals Quantification of black carbon mixing state from traffic: implications for aerosol optical properties

2015 ◽  
Vol 15 (22) ◽  
pp. 33555-33582 ◽  
Author(s):  
M. D. Willis ◽  
R. M. Healy ◽  
N. Riemer ◽  
M. West ◽  
J. M. Wang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Black Carbon ◽  
Chemical Properties ◽  
Mixing State ◽  
Aerosol Optical Properties ◽  
Aerosol Composition ◽  
Average Mass ◽  
Measurement Capability ◽  
Aerosol Mass ◽  
Physical And Chemical

Abstract. The climatic impacts of black carbon (BC) aerosol, an important absorber of solar radiation in the atmosphere, remain poorly constrained and are intimately related to its particle-scale physical and chemical properties. Using particle-resolved modelling informed by quantitative measurements from a soot-particle aerosol mass spectrometer, we confirm that the mixing state (the distribution of co-emitted aerosol amongst fresh BC-containing particles) at the time of emission significantly affects BC-aerosol optical properties even after a day of atmospheric processing. Both single particle and ensemble aerosol mass spectrometry observations indicate that BC near the point of emission co-exists with hydrocarbon-like organic aerosol in two distinct particle types: HOA-rich and BC-rich particles. The average mass fraction of black carbon in HOA-rich and BC-rich particles was 0.02–0.08 and 0.72–0.93, respectively. Notably, approximately 90 % of BC mass resides in BC-rich particles. This new measurement capability provides quantitative insight into the physical and chemical nature of BC-containing particles and is used to drive a particle-resolved aerosol box model. Significant differences in calculated single scattering albedo (an increase of 0.1) arise from accurate treatment of initial particle mixing state as compared to the assumption of uniform aerosol composition at the point of BC injection into the atmosphere.

scholarly journals The single-particle mixing state and cloud scavenging of black carbon: a case study at a high-altitude mountain site in southern China

2017 ◽  
Vol 17 (24) ◽  
pp. 14975-14985 ◽  
Author(s):  
Guohua Zhang ◽  
Qinhao Lin ◽  
Long Peng ◽  
Xinhui Bi ◽  
Duohong Chen ◽  
...  
Keyword(s):  
Black Carbon ◽  
Single Particle ◽  
Southern China ◽  
Cloud Droplet ◽  
Mixing State ◽  
Cloud Droplets ◽  
Aerosol Mass ◽  
Mountain Site ◽  
Cloud Scavenging ◽  
Scavenging Efficiency

Abstract. In the present study, a ground-based counterflow virtual impactor (GCVI) was used to sample cloud droplet residual (cloud RES) particles, while a parallel PM2.5 inlet was used to sample cloud-free or cloud interstitial (cloud INT) particles. The mixing state of black carbon (BC)-containing particles and the mass concentrations of BC in the cloud-free, RES and INT particles were investigated using a single-particle aerosol mass spectrometer (SPAMS) and two aethalometers, respectively, at a mountain site (1690 m a. s. l. ) in southern China. The measured BC-containing particles were extensively internally mixed with sulfate and were scavenged into cloud droplets (with number fractions of 0.05–0.45) to a similar (or slightly lower) extent as all the measured particles (0.07–0.6) over the measured size range of 0.1–1.6 µm. The results indicate the preferential activation of larger particles and/or that the production of secondary compositions shifts the BC-containing particles towards larger sizes. BC-containing particles with an abundance of both sulfate and organics were scavenged less than those with sulfate but limited organics, implying the importance of the mixing state on the incorporation of BC-containing particles into cloud droplets. The mass scavenging efficiency of BC with an average of 33 % was similar for different cloud events independent of the air mass. This is the first time that both the mixing state and cloud scavenging of BC in China have been reported. Our results would improve the knowledge on the concentration, mixing state, and cloud scavenging of BC in the free troposphere.

scholarly journals Modeling the smoky troposphere of the southeast Atlantic: a comparison to ORACLES airborne observations from September of 2016

2020 ◽  
Vol 20 (19) ◽  
pp. 11491-11526 ◽  
Author(s):  
Yohei Shinozuka ◽  
Pablo E. Saide ◽  
Gonzalo A. Ferrada ◽  
Sharon P. Burton ◽  
Richard Ferrare ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Optical Properties ◽  
Black Carbon ◽  
Marine Boundary Layer ◽  
Organic Aerosol ◽  
Airborne Lidar ◽  
Aerosol Mass ◽  
Wide Range ◽  
Smoke Layer ◽  
Mass Concentrations

Abstract. In the southeast Atlantic, well-defined smoke plumes from Africa advect over marine boundary layer cloud decks; both are most extensive around September, when most of the smoke resides in the free troposphere. A framework is put forth for evaluating the performance of a range of global and regional atmospheric composition models against observations made during the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) airborne mission in September 2016. A strength of the comparison is a focus on the spatial distribution of a wider range of aerosol composition and optical properties than has been done previously. The sparse airborne observations are aggregated into approximately 2∘ grid boxes and into three vertical layers: 3–6 km, the layer from cloud top to 3 km, and the cloud-topped marine boundary layer. Simulated aerosol extensive properties suggest that the flight-day observations are reasonably representative of the regional monthly average, with systematic deviations of 30 % or less. Evaluation against observations indicates that all models have strengths and weaknesses, and there is no single model that is superior to all the others in all metrics evaluated. Whereas all six models typically place the top of the smoke layer within 0–500 m of the airborne lidar observations, the models tend to place the smoke layer bottom 300–1400 m lower than the observations. A spatial pattern emerges, in which most models underestimate the mean of most smoke quantities (black carbon, extinction, carbon monoxide) on the diagonal corridor between 16∘ S, 6∘ E, and 10∘ S, 0∘ E, in the 3–6 km layer, and overestimate them further south, closer to the coast, where less aerosol is present. Model representations of the above-cloud aerosol optical depth differ more widely. Most models overestimate the organic aerosol mass concentrations relative to those of black carbon, and with less skill, indicating model uncertainties in secondary organic aerosol processes. Regional-mean free-tropospheric model ambient single scattering albedos vary widely, between 0.83 and 0.93 compared with in situ dry measurements centered at 0.86, despite minimal impact of humidification on particulate scattering. The modeled ratios of the particulate extinction to the sum of the black carbon and organic aerosol mass concentrations (a mass extinction efficiency proxy) are typically too low and vary too little spatially, with significant inter-model differences. Most models overestimate the carbonaceous mass within the offshore boundary layer. Overall, the diversity in the model biases suggests that different model processes are responsible. The wide range of model optical properties requires further scrutiny because of their importance for radiative effect estimates.

scholarly journals Tethered balloon-borne aerosol measurements: seasonal and vertical variations of aerosol constituents over Syowa Station, Antarctica

2013 ◽  
Vol 13 (3) ◽  
pp. 8153-8211
Author(s):  
K. Hara ◽  
K. Osada ◽  
T. Yamanouchi
Keyword(s):  
Boundary Layer ◽  
Relative Abundance ◽  
Lower Troposphere ◽  
Sea Salt ◽  
Heterogeneous Reactions ◽  
Aerosol Sampling ◽  
Free Troposphere ◽  
Tethered Balloon ◽  
Syowa Station ◽  
Salt Fractionation

Abstract. Tethered balloon-borne aerosol measurements were conducted at Syowa Station, Antarctica during the 46th Japanese Antarctic expedition (2005–2006). Direct aerosol sampling was operated from near the surface to the lower free troposphere (approximately 2500 m) using a balloon-borne aerosol impactor. Individual aerosol particles were analyzed using a scanning electron microscope equipped with an energy dispersive X-ray spectrometer. Seasonal and vertical features of aerosol constituents and their mixing states were investigated. Results show that sulfate particles were dominant in the boundary layer and lower free troposphere in the summer, whereas sea-salt particles were dominant during winter–spring. Minerals, MgSO4, and sulfate containing K were identified as minor aerosol constituents in both boundary layer and free troposphere over Syowa Station. Although sea-salt particles were dominant during winter–spring, the relative abundance of sulfate particles increased in the boundary layer when air masses fell from the free troposphere over the Antarctic coast and continent. Sea-salt particles were modified considerably through heterogeneous reactions with SO42−, CH3SO3−, and their precursors during the summer, and were modified slightly through heterogeneous reactions with NO3− and its precursors. During winter–spring, sea-salt modification was insignificant, particularly in the cases of high relative abundance of sea-salt particles and higher number concentrations. In August, NO3− and its precursors contributed greatly to sea-salt modification over Syowa Station. Because of the occurrence of sea-salt fractionation on sea-ice, Mg-rich sea-salt particles were identified during April–November. In contrast, Mg-free sea-salt particles and slightly Mg-rich sea-salt particles co-existed in the lower troposphere during summer. Thereby, Mg separation can proceed by sea-salt fractionation during summer in Antarctic regions.

scholarly journals Measurement of turbulent water vapor fluxes using a lightweight unmanned aerial vehicle system

2011 ◽  
Vol 4 (4) ◽  
pp. 5529-5568 ◽  
Author(s):  
R. M. Thomas ◽  
K. Lehmann ◽  
H. Nguyen ◽  
D. L. Jackson ◽  
D. Wolfe ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Unmanned Aerial Vehicle ◽  
System Development ◽  
Spatial Scales ◽  
Ground Level ◽  
Heat Fluxes ◽  
Data Logging ◽  
Pass Filter ◽  
Aerial Vehicle

Abstract. We present here the first application of a lightweight unmanned aerial vehicle (UAV) system designed to measure turbulent properties and vertical latent heat fluxes (λE). Such measurements are crucial to improve our understanding of linkages between surface moisture supply and boundary layer clouds and phenomena such as atmospheric rivers. The application of UAVs allows for measurements on spatial scales complimentary to satellite, aircraft, and tower derived fluxes. Key system components are: a turbulent gust probe; a fast response water vapor sensor; an inertial navigation system (INS) coupled to global positioning system (GPS); and a 100 Hz data logging system. We present measurements made in the continental boundary layer at the National Aeronautics and Space Administration (NASA) Dryden Research Flight Facility located in the Mojave Desert. Two flights consisting of several horizontal straight flux run legs up to ten kilometers in length and between 330 and 930 m above ground level (m a.g.l.) are compared to measurement from a surface tower. Surface measured λE ranged from −53 W m−2 to 41 W m−2, and the application of a Butterworth High Pass Filter (HPF) to the datasets improved agreement to within ± 12 W m−2 for 86 % of flux runs, by removing improperly sampled low frequency flux contributions. This result, along with power and co-spectral comparisons and consideration of the differing spatial scales indicates the system is able to resolve vertical fluxes for the measurement conditions encountered. Challenges remain, and the outcome of these measurements will be used to inform future sampling strategies and further system development.

scholarly journals In situ chemical measurement of individual cloud residue particles at a mountain site, South China

2017 ◽  
Author(s):  
Qinhao Lin ◽  
Guohua Zhang ◽  
Long Peng ◽  
Xinhui Bi ◽  
Xinming Wang ◽  
...  
Keyword(s):  
Chemical Composition ◽  
South China ◽  
Chemical Properties ◽  
In Situ Observation ◽  
Mountain Range ◽  
Mixing State ◽  
Cloud Droplets ◽  
Air Masses ◽  
Aerosol Mass

Abstract. To estimate how atmospheric aerosol particles respond to chemical properties of cloud droplets, a ground-based counterflow virtual impactor (GCVI) coupled with a real-time single-particle aerosol mass spectrometer (SPAMS) was used to assess the chemical composition and mixing state of individual cloud residue particles in the Nanling Mountain Range (1,690 m a.s.l.), South China, in January 2016. The cloud residues were classified into nine particle types: Aged elemental carbon (EC), Potassium-rich (K-rich), Amine, Dust, Pb, Fe, Organic carbon (OC), Sodium-rich (Na-rich) and Other. The largest fraction of the cloud residues was the aged EC type (49.3 % by number), followed by the K-rich type (33.9 % by number). Abundant aged EC cloud residues that internally mixed with inorganic salts were found in air masses from northerly polluted areas. The number fraction (Nf) of the K-rich cloud residues significantly increased within southwesterly air masses from fire activities in Southeast Asia. In addition, the Amine particles represented 0.2 % to 15.1 % by number to the cloud residues when air masses changed from northerly to southwesterly sources. The Dust, Fe, Pb, Na-rich and OC particles had a low contribution (0.5–4.1 % by number) to the cloud residues. An analysis of the mixing state of cloud residues showed that the Dust and Na-rich cloud residues were highly associated with nitrate. Sulfate intensity increased in the aged EC and OC cloud residues and decreased in the Dust and Na-rich cloud residues relative to both ambient and interstitial particles. A comparison of cloud residues with interstitial particles indicated that a higher Nf for K-rich particles and a lower Nf for the aged EC particles were found in the cloud residues. Relative to the ambient and interstitial particles, the cloud residues exhibited larger size distributions. To our knowledge, this study is the first report on in situ observation of the chemical composition and mixing state of individual cloud residue particles in China. This study increases our understanding of the impacts of aerosols on cloud droplets in a remote area of China.

scholarly journals Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

2014 ◽  
Vol 14 (22) ◽  
pp. 12109-12132 ◽  
Author(s):  
S. Decesari ◽  
J. Allan ◽  
C. Plass-Duelmer ◽  
B. J. Williams ◽  
M. Paglione ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Black Carbon ◽  
Mass Spectrometer ◽  
Organic Aerosol ◽  
Spectroscopic Techniques ◽  
Mixing State ◽  
Mass Spectrometers ◽  
Aerosol Mass Spectrometer ◽  
Po Valley ◽  
Aerosol Mass

Abstract. The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterised by a less dense urbanisation. We present here the results obtained at a background site in the Po Valley, Italy, in summer 2009. For the first time in Europe, six state-of-the-art spectrometric techniques were used in parallel: aerosol time-of-flight mass spectrometer (ATOFMS), two aerosol mass spectrometers (high-resolution time-of-flight aerosol mass spectrometer – HR-ToF-AMS and soot particle aerosol mass spectrometer – SP-AMS), thermal desorption aerosol gas chromatography (TAG), chemical ionisation mass spectrometry (CIMS) and (offline) proton nuclear magnetic resonance (1H-NMR) spectroscopy. The results indicate that, under high-pressure conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC), secondary semivolatile compounds such as ammonium nitrate and amines and a class of monocarboxylic acids which correspond to the AMS cooking organic aerosol (COA) already identified in urban areas. In daytime, the entrainment of aged air masses in the mixing layer is responsible for the accumulation of low-volatility oxygenated organic aerosol (LV-OOA) and also for the recycling of non-volatile primary species such as black carbon. According to organic aerosol source apportionment, anthropogenic aerosols accumulating in the lower layers overnight accounted for 38% of organic aerosol mass on average, another 21% was accounted for by aerosols recirculated in residual layers but still originating in northern Italy, while a substantial fraction (41%) was due to the most aged aerosols imported from transalpine areas. The different meteorological regimes also affected the BC mixing state: in periods of enhanced stagnation and recirculation of pollutants, the number fraction of the BC-containing particles determined by ATOFMS was 75% of the total, while in the days of enhanced ventilation of the planetary boundary layer (PBL), such fraction was significantly lower (50%) because of the relative greater influence of non-BC-containing aerosol local sources in the Po Valley. Overall, a full internal mixing between BC and the non-refractory aerosol chemical components was not observed during the experiment in this environment.

scholarly journals Black carbon aerosol mixing state, organic aerosols and aerosol optical properties over the UK

2011 ◽  
Vol 11 (5) ◽  
pp. 14991-15027 ◽  
Author(s):  
G. R. McMeeking ◽  
W. T. Morgan ◽  
M. Flynn ◽  
E. J. Highwood ◽  
K. Turnbull ◽  
...  
Keyword(s):  
Optical Properties ◽  
Black Carbon ◽  
Radiative Forcing ◽  
Organic Aerosols ◽  
Mixing State ◽  
Aerosol Composition ◽  
Air Masses ◽  
Aerosol Mass ◽  
The Uk ◽  
Urban Plumes

Abstract. Black carbon (BC) aerosols absorb sunlight thereby leading to a positive radiative forcing and a warming of climate and can also impact human health through their impact on the respiratory system. The state of mixing of BC with other aerosol species, particularly the degree of internal/external mixing, has been highlighted as a major uncertainty in assessing its radiative forcing and hence its climate impact, but few in situ observations of mixing state exist. We present airborne single particle soot photometer (SP2) measurements of refractory BC (rBC) mass concentrations and mixing state coupled with aerosol composition and optical properties measured in urban plumes and regional pollution over the UK. All data were obtained using instrumentation flown on the UK's BAe-146-301 large Atmospheric Research Aircraft (ARA) operated by the Facility for Airborne Atmospheric Measurements (FAAM). We measured sub-micron aerosol composition using an aerosol mass spectrometer (AMS) and used positive matrix factorization to separate hydrocarbon-like (HOA) and oxygenated organic aerosols (OOA). We found a higher number fraction of thickly coated rBC particles in air masses with large OOA relative to HOA, higher ozone-to-nitrogen oxides (NOx) ratios and large concentrations of total sub-micron aerosol mass relative to rBC mass concentrations. The more ozone- and OOA-rich air masses were associated with transport from continental Europe, while plumes from UK cities had higher HOA and NOx and fewer thickly coated rBC particles. We did not observe any significant change in the rBC mass absorption efficiency calculated from rBC mass and light absorption coefficients measured by a particle soot absorption photometer despite observing significant changes in aerosol composition and rBC mixing state. The contributions of light scattering and absorption to total extinction (quantified by the single scattering albedo; SSA) did change for different air masses, with lower SSA observed in urban plumes compared to regional aerosol (0.85 versus 0.9–0.95). We attribute these differences to the presence of relatively rapidly formed secondary aerosol, primarily OOA and ammonium nitrate, which must be taken into account in radiative forcing calculations.

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