scholarly journals Submicron Aerosol Chemical Composition and Optical Properties: In Situ Field Measurements and Controlled Laboratory Studies to Probe Dynamic Particle Processes for Climate

2019 ◽  
Author(s):  
Allison C. Aiken
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
Field Measurements ◽  
Laboratory Studies ◽  
Submicron Aerosol ◽  
Aerosol Chemical Composition

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 Relationship between the Optical Properties and Chemical Composition of Urban Aerosol Particles in Lithuania

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Julija Pauraite ◽  
Kristina Plauškaitė ◽  
Vadimas Dudoitis ◽  
Vidmantas Ulevicius
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
Organic Aerosol ◽  
Single Scattering ◽  
Chemical Compositions ◽  
Spectra Analysis ◽  
Average Value ◽  
Aerosol Mass ◽  
In Situ Investigation

In situ investigation results of aerosol optical properties (absorption and scattering) and chemical composition at an urban background site in Lithuania (Vilnius) are presented. Investigation was performed in May-June 2017 using an aerosol chemical speciation monitor (ACSM), a 7-wavelength Aethalometer and a 3-wavelength integrating Nephelometer. A positive matrix factorisation (PMF) was used for the organic aerosol mass spectra analysis to characterise the sources of ambient organic aerosol (OA). Five OA factors were identified: hydrocarbon-like OA (HOA), biomass-burning OA (BBOA), more and less oxygenated OA (LVOOA and SVOOA, respectively), and local hydrocarbon-like OA (LOA). The average absorption (at 470 nm) and scattering (at 450 nm) coefficients during the entire measurement campaign were 16.59 Mm−1 (standard deviation (SD) = 17.23 Mm−1) and 29.83 Mm−1 (SD = 20.45 Mm−1), respectively. Furthermore, the absorption and scattering Angström exponents (AAE and SAE, respectively) and single-scattering albedo (SSA) were calculated. The average AAE value at 470/660 nm was 0.97 (SD = 0.16) indicating traffic-related black carbon (BCtr) dominance. The average value of SAE (at 450/700 nm) was 1.93 (SD = 0.32) and could be determined by the submicron particle (PM1) dominance versus the supermicron ones (PM > 1 µm). The average value of SSA was 0.62 (SD = 0.13). Several aerosol types showed specific segregation in the SAE versus SSA plot, which underlines different optical properties due to various chemical compositions.

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 Characterization of submicron aerosol chemical composition and sources in the coastal area of Central Chile

2019 ◽  
Vol 199 ◽  
pp. 391-401 ◽  
Author(s):  
S. Saarikoski ◽  
F. Reyes ◽  
Y. Vázquez ◽  
M. Tagle ◽  
H. Timonen ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Coastal Area ◽  
Central Chile ◽  
Submicron Aerosol ◽  
Aerosol Chemical Composition

scholarly journals Using different assumptions of aerosol mixing state and chemical composition to predict CCN concentrations based on field measurements in urban Beijing

2018 ◽  
Vol 18 (9) ◽  
pp. 6907-6921 ◽  
Author(s):  
Jingye Ren ◽  
Fang Zhang ◽  
Yuying Wang ◽  
Don Collins ◽  
Xinxin Fan ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Black Carbon ◽  
Cloud Condensation Nuclei ◽  
Field Measurements ◽  
Minor Role ◽  
Mixing State ◽  
Mixing Processes ◽  
Size Dependent ◽  
Aerosol Mixing State ◽  
Aerosol Chemical Composition

Abstract. Understanding the impacts of aerosol chemical composition and mixing state on cloud condensation nuclei (CCN) activity in polluted areas is crucial for accurately predicting CCN number concentrations (NCCN). In this study, we predict NCCN under five assumed schemes of aerosol chemical composition and mixing state based on field measurements in Beijing during the winter of 2016. Our results show that the best closure is achieved with the assumption of size dependent chemical composition for which sulfate, nitrate, secondary organic aerosols, and aged black carbon are internally mixed with each other but externally mixed with primary organic aerosol and fresh black carbon (external–internal size-resolved, abbreviated as EI–SR scheme). The resulting ratios of predicted-to-measured NCCN (RCCN_p∕m) were 0.90 – 0.98 under both clean and polluted conditions. Assumption of an internal mixture and bulk chemical composition (INT–BK scheme) shows good closure with RCCN_p∕m of 1.0 –1.16 under clean conditions, implying that it is adequate for CCN prediction in continental clean regions. On polluted days, assuming the aerosol is internally mixed and has a chemical composition that is size dependent (INT–SR scheme) achieves better closure than the INT–BK scheme due to the heterogeneity and variation in particle composition at different sizes. The improved closure achieved using the EI–SR and INT–SR assumptions highlight the importance of measuring size-resolved chemical composition for CCN predictions in polluted regions. NCCN is significantly underestimated (with RCCN_p∕m of 0.66 – 0.75) when using the schemes of external mixtures with bulk (EXT–BK scheme) or size-resolved composition (EXT–SR scheme), implying that primary particles experience rapid aging and physical mixing processes in urban Beijing. However, our results show that the aerosol mixing state plays a minor role in CCN prediction when the κorg exceeds 0.1.

scholarly journals First insights into Northern Africa high-altitude background aerosol chemical composition and source influences

2021 ◽  
Author(s):  
Nabil Deabji ◽  
Khanneh Wadinga Fomba ◽  
Souad El Hajjaji ◽  
Abdelwahid Mellouki ◽  
Hartmut Herrmann
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
High Altitude ◽  
Field Measurements ◽  
High Volume ◽  
Ionic Species ◽  
Atmospheric Composition ◽  
Chemical Compositions ◽  
Aerosol Composition ◽  
Aerosol Chemical Composition

Abstract. Field measurements were conducted to determine aerosol chemical composition in a newly established remote high-altitude site in North Africa to investigate the variations in aerosol composition useful in assessing global and regional changes in atmospheric composition. Particulate matter (PM10) filter samples (200) were collected at the Atlas Mohammed V atmospheric observatory (AM5) located in the Middle-Atlas Mountains in Morocco using a high-volume (HV) collector in a 12 h sampling interval from August to December 2017. The chemical composition of the samples was analyzed for trace metals, ions, elemental carbon, organic carbon, aliphatic hydrocarbons, and polycyclic aromatic hydrocarbon (PAHs) content. The results indicate that high-altitudes aerosol composition is influenced by both regional as well as trans-regional transport of emissions. However, local sources play an important role, especially during low wind speed periods, as observed for November and December. Despite the proximity of the site to the Sahara Desert, its influence on the atmospheric composition at this high-altitude site was mainly seasonal and accounted for only 14 % of the sampling duration. Background conditions at this remote site are characterized by low wind speeds (Av. 2.5 m/s) and mass concentrations in the range of 9.8 and 20 µg/m3. The chemical composition is found to be dominated by inorganic elements, mainly suspended dust (47 %) and ionic species (16 %), followed by organic matter (15 %), water content (12 %), and indeterminate mass (9 %). Biogenic organics contributed up to 7 % of the organic matter with high contributions from compounds such as Nonacosane, Heptacosane, and 2-Pentadecanone. The AM5 site is dominated by four main air mass inflow, which often leads to different aerosol chemical compositions. Mineral dust influenced was seasonal and ranged between 20 and 70 % of the PM mass with peaks observed during the summer and was accompanied by high concentrations of SO42− of up to 1.3 µg/m3. During winter, PM10 concentrations are low (

scholarly journals Relating aerosol absorption due to soot, organic carbon, and dust to emission sources determined from in-situ chemical measurements

2013 ◽  
Vol 13 (18) ◽  
pp. 9337-9350 ◽  
Author(s):  
A. Cazorla ◽  
R. Bahadur ◽  
K. J. Suski ◽  
J. F. Cahill ◽  
D. Chand ◽  
...  
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
Radiative Forcing ◽  
Wavelength Dependence ◽  
Optical Measurements ◽  
Carbonaceous Aerosols ◽  
Angstrom Exponent ◽  
Ångström Exponent ◽  
Ångstrom Exponent

Abstract. Estimating the aerosol contribution to the global or regional radiative forcing can take advantage of the relationship between the spectral aerosol optical properties and the size and chemical composition of aerosol. Long term global optical measurements from observational networks or satellites can be used in such studies. Using in-situ chemical mixing state measurements can help us to constrain the limitations of such estimates. In this study, the Absorption Ångström Exponent (AAE) and the Scattering Ångström Exponent (SAE) derived from 10 operational AERONET sites in California are combined for deducing chemical speciation based on wavelength dependence of the optical properties. In addition, in-situ optical properties and single particle chemical composition measured during three aircraft field campaigns in California between 2010 and 2011 are combined in order to validate the methodology used for the estimates of aerosol chemistry using spectral optical properties. Results from this study indicate a dominance of mixed types in the classification leading to an underestimation of the primary sources, however secondary sources are better classified. The distinction between carbonaceous aerosols from fossil fuel and biomass burning origins is not clear, since their optical properties are similar. On the other hand, knowledge of the aerosol sources in California from chemical studies help to identify other misclassification such as the dust contribution.

Sea spray aerosol chemical composition: elemental and molecular mimics for laboratory studies of heterogeneous and multiphase reactions

2018 ◽  
Vol 47 (7) ◽  
pp. 2374-2400 ◽  
Author(s):  
Timothy H. Bertram ◽  
Richard E. Cochran ◽  
Vicki H. Grassian ◽  
Elizabeth A. Stone
Keyword(s):  
Chemical Composition ◽  
Aerosol Particle ◽  
Sea Spray ◽  
Laboratory Studies ◽  
Organic Film ◽  
Schematic Representation ◽  
Multiphase Reactions ◽  
Sea Spray Aerosol ◽  
Aerosol Chemical Composition

Schematic representation of the reactive uptake of N2O5to a sea spray aerosol particle containing a thick organic film.

Surface submicron aerosol chemical composition: What fraction is not sulfate?

2000 ◽  
Vol 105 (D5) ◽  
pp. 6785-6805 ◽  
Author(s):  
P. K. Quinn ◽  
T. S. Bates ◽  
T. L. Miller ◽  
D. J. Coffman ◽  
J. E. Johnson ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Submicron Aerosol ◽  
Aerosol Chemical Composition
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