scholarly journals Aging of black carbon in outflow from anthropogenic sources using a mixing state resolved model: 2. Aerosol optical properties and cloud condensation nuclei activities

2009 ◽  
Vol 114 (D18) ◽  
Author(s):  
N. Oshima ◽  
M. Koike ◽  
Y. Zhang ◽  
Y. Kondo
Keyword(s):  
Optical Properties ◽  
Black Carbon ◽  
Cloud Condensation Nuclei ◽  
Anthropogenic Sources ◽  
Condensation Nuclei ◽  
Mixing State ◽  
Aerosol Optical Properties

scholarly journals Estimating cloud condensation nuclei number concentrations using aerosol optical properties: role of particle number size distribution and parameterization

2019 ◽  
Vol 19 (24) ◽  
pp. 15483-15502 ◽  
Author(s):  
Yicheng Shen ◽  
Aki Virkkula ◽  
Aijun Ding ◽  
Krista Luoma ◽  
Helmi Keskinen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Size Distributions ◽  
Condensation Nuclei ◽  
Aerosol Optical Properties ◽  
Average Bias ◽  
Angstrom Exponent ◽  
Ångström Exponent ◽  
Ångstrom Exponent

Abstract. The concentration of cloud condensation nuclei (CCN) is an essential parameter affecting aerosol–cloud interactions within warm clouds. Long-term CCN number concentration (NCCN) data are scarce; there are a lot more data on aerosol optical properties (AOPs). It is therefore valuable to derive parameterizations for estimating NCCN from AOP measurements. Such parameterizations have already been made, and in the present work a new parameterization is presented. The relationships between NCCN, AOPs, and size distributions were investigated based on in situ measurement data from six stations in very different environments around the world. The relationships were used for deriving a parameterization that depends on the scattering Ångström exponent (SAE), backscatter fraction (BSF), and total scattering coefficient (σsp) of PM10 particles. The analysis first showed that the dependence of NCCN on supersaturation (SS) can be described by a logarithmic fit in the range SS <1.1 %, without any theoretical reasoning. The relationship between NCCN and AOPs was parameterized as NCCN≈((286±46)SAE ln(SS/(0.093±0.006))(BSF − BSFmin) + (5.2±3.3))σsp, where BSFmin is the minimum BSF, in practice the 1st percentile of BSF data at a site to be analyzed. At the lowest supersaturations of each site (SS ≈0.1 %), the average bias, defined as the ratio of the AOP-derived and measured NCCN, varied from ∼0.7 to ∼1.9 at most sites except at a Himalayan site where the bias was >4. At SS >0.4 % the average bias ranged from ∼0.7 to ∼1.3 at most sites. For the marine-aerosol-dominated site Ascension Island the bias was higher, ∼1.4–1.9. In other words, at SS >0.4 % NCCN was estimated with an average uncertainty of approximately 30 % by using nephelometer data. The biases were mainly due to the biases in the parameterization related to the scattering Ångström exponent (SAE). The squared correlation coefficients between the AOP-derived and measured NCCN varied from ∼0.5 to ∼0.8. To study the physical explanation of the relationships between NCCN and AOPs, lognormal unimodal particle size distributions were generated and NCCN and AOPs were calculated. The simulation showed that the relationships of NCCN and AOPs are affected by the geometric mean diameter and width of the size distribution and the activation diameter. The relationships of NCCN and AOPs were similar to those of the observed ones.

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 Altitude profiles of cloud condensation nuclei characteristics across the Indo-Gangetic Plain prior to the onset of the Indian summer monsoon

2020 ◽  
Vol 20 (1) ◽  
pp. 561-576 ◽  
Author(s):  
Venugopalan Nair Jayachandran ◽  
Surendran Nair Suresh Babu ◽  
Aditya Vaishya ◽  
Mukunda M. Gogoi ◽  
Vijayakumar S. Nair ◽  
...  
Keyword(s):  
Optical Properties ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Cloud Condensation Nuclei ◽  
Condensation Nuclei ◽  
Aerosol Optical Properties ◽  
Gangetic Plain ◽  
Air Mass ◽  
Activation Efficiency ◽  
Indo Gangetic Plain

Abstract. Concurrent measurements of the altitude profiles of the concentration of cloud condensation nuclei (CCN), as a function of supersaturation (ranging from 0.2 % to 1.0 %), and aerosol optical properties (scattering and absorption coefficients) were carried out aboard an instrumented aircraft across the Indo-Gangetic Plain (IGP) just prior to the onset of the Indian summer monsoon (ISM) of 2016. The experiment was conducted under the aegis of the combined South-West Asian Aerosol–Monsoon Interactions and Regional Aerosol Warming Experiment (SWAAMI–RAWEX) campaign. The measurements covered coastal, urban and arid environments. In general, the CCN concentration was highest in the central IGP, decreasing spatially from east to west above the planetary boundary layer (PBL), which is ∼1.5 km for the IGP during pre-monsoon period. Despite this, the CCN activation efficiency at 0.4 % supersaturation was, interestingly, the highest over the eastern IGP (∼72 %), followed by that in the west (∼61 %), and it was the least over the central IGP (∼24 %) within the PBL. In general, higher activation efficiency is noticed above the PBL than below it. The central IGP showed remarkably low CCN activation efficiency at all altitudes, which appears to be associated with high black carbon (BC) mass concentration there, indicating the role of anthropogenic sources in suppressing the CCN efficiency. These first-ever CCN measurements over the western IGP, encompassing “the Great Indian Desert” also known as “the Thar Desert”, showed high CCN efficiency, ∼61 % at 0.4 % supersaturation, indicating the hygroscopic nature of the dust. The vertical structure of CCN properties is found to be air mass dependent, with higher activation efficiency even over the central IGP during the prevalence of marine air mass. Wet scavenging associated with precipitation episodes seems to have reduced the CCN activation efficiency below cloud level. An empirical relation has emerged between the CCN concentration and the scattering aerosol index (AI), which would facilitate the prediction of CCN from aerosol optical properties.

scholarly journals Modelling black carbon absorption of solar radiation: combining external and internal mixing assumptions

2019 ◽  
Vol 19 (1) ◽  
pp. 181-204 ◽  
Author(s):  
Gabriele Curci ◽  
Ummugulsum Alyuz ◽  
Rocio Barò ◽  
Roberto Bianconi ◽  
Johannes Bieser ◽  
...  
Keyword(s):  
Optical Properties ◽  
Black Carbon ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Absorption Enhancement ◽  
Core Shell ◽  
Mixing State ◽  
Aerosol Optical Properties ◽  
Internal Mixing ◽  
Carbon Absorption

Abstract. An accurate simulation of the absorption properties is key for assessing the radiative effects of aerosol on meteorology and climate. The representation of how chemical species are mixed inside the particles (the mixing state) is one of the major uncertainty factors in the assessment of these effects. Here we compare aerosol optical properties simulations over Europe and North America, coordinated in the framework of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII), to 1 year of AERONET sunphotometer retrievals, in an attempt to identify a mixing state representation that better reproduces the observed single scattering albedo and its spectral variation. We use a single post-processing tool (FlexAOD) to derive aerosol optical properties from simulated aerosol speciation profiles, and focus on the absorption enhancement of black carbon when it is internally mixed with more scattering material, discarding from the analysis scenes dominated by dust. We found that the single scattering albedo at 440 nm (ω0,440) is on average overestimated (underestimated) by 3–5 % when external (core-shell internal) mixing of particles is assumed, a bias comparable in magnitude with the typical variability of the quantity. The (unphysical) homogeneous internal mixing assumption underestimates ω0,440 by ∼14 %. The combination of external and core-shell configurations (partial internal mixing), parameterized using a simplified function of air mass aging, reduces the ω0,440 bias to -1/-3 %. The black carbon absorption enhancement (Eabs) in core-shell with respect to the externally mixed state is in the range 1.8–2.5, which is above the currently most accepted upper limit of ∼1.5. The partial internal mixing reduces Eabs to values more consistent with this limit. However, the spectral dependence of the absorption is not well reproduced, and the absorption Ångström exponent AAE675440 is overestimated by 70–120 %. Further testing against more comprehensive campaign data, including a full characterization of the aerosol profile in terms of chemical speciation, mixing state, and related optical properties, would help in putting a better constraint on these calculations.

scholarly journals Modelling black carbon absorption of solar radiation: combining external and internal mixing assumptions

2018 ◽  
Author(s):  
Gabriele Curci ◽  
Ummugulsum Alyuz ◽  
Rocio Barò ◽  
Roberto Bianconi ◽  
Johannes Bieser ◽  
...  
Keyword(s):  
Optical Properties ◽  
Black Carbon ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Absorption Enhancement ◽  
Core Shell ◽  
Mixing State ◽  
Aerosol Optical Properties ◽  
Internal Mixing ◽  
Carbon Absorption

Abstract. An accurate simulation of the absorption properties is key for assessing the radiative effects of aerosol on meteorology and climate. The representation of how chemical species are mixed inside the particles (the mixing state) is one of the major uncertainty factors in the assessment of these effects. Here we compare aerosol optical properties simulations over Europe and North America, coordinated in the framework of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII), to one year of AERONET sunphotometer retrievals, in an attempt to identify a mixing state representation that better reproduces the observed single scattering albedo and its spectral variation. We use a single post-processing tool (FlexAOD) to derive aerosol optical properties from simulated aerosol speciation profiles, and focus on the absorption enhancement of black carbon when it is internally mixed with more scattering material, discarding from the analysis scenes dominated by dust. We found that the single scattering albedo at 440 nm (ω0,440) is on average overestimated (underestimated) by 3–5 % when external (core-shell internal) mixing of particles is assumed, a bias comparable in magnitude with the typical variability of the quantity. The (unphysical) homogeneous internal mixing assumption underestimates ω0,440 by ~ 14 %. The combination of external and core-shell configurations (partial internal mixing), parameterized using a simplified function of air mass aging, reduces the ω0,440 bias to −1/−3 %. The black carbon absorption enhancement (Eabs) in core-shell with respect to the externally mixed state is in the range 1.8–2.5, which is above the currently most accepted upper limit of ~ 1.5. The partial internal mixing reduces Eabs to values more consistent with this limit. However, the spectral dependence of the absorption is not well reproduced, and the absorption Angostrom exponent AAE440675 is overestimated by 70–120 %. Further testing against more comprehensive campaign data, including a full characterization of the aerosol profile in terms of chemical speciation, mixing state, and related optical properties, would help in putting a better constraint on these calculations.

Sign in / Sign up

Export Citation Format

Share Document