scholarly journals Cloud-nucleating properties of the Amazonian biomass burning aerosol: Cloud condensation nuclei measurements and modeling

2007 ◽  
Vol 112 (D14) ◽  
Author(s):  
A. Vestin ◽  
J. Rissler ◽  
E. Swietlicki ◽  
G. P. Frank ◽  
M. O. Andreae
Keyword(s):  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Condensation Nuclei ◽  
Aerosol Cloud ◽  
Biomass Burning Aerosol

scholarly journals Cloud condensation nuclei activity of fresh primary and aged biomass burning aerosol

2012 ◽  
Vol 12 (15) ◽  
pp. 7285-7293 ◽  
Author(s):  
G. J. Engelhart ◽  
C. J. Hennigan ◽  
M. A. Miracolo ◽  
A. L. Robinson ◽  
S. N. Pandis
Keyword(s):  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Organic Aerosol ◽  
Condensation Nuclei ◽  
Hygroscopic Properties ◽  
A Value ◽  
Biomass Burning Aerosol ◽  
Photochemical Processing ◽  
Photochemical Aging ◽  
Aerosol Emissions

Abstract. We quantify the hygroscopic properties of particles freshly emitted from biomass burning and after several hours of photochemical aging in a smog chamber. Values of the hygroscopicity parameter, κ, were calculated from cloud condensation nuclei (CCN) measurements of emissions from combustion of 12 biomass fuels commonly burned in North American wildfires. Prior to photochemical aging, the κ of the fresh primary aerosol varied widely, between 0.06 (weakly hygroscopic) and 0.6 (highly hygroscopic). The hygroscopicity of the primary aerosol was positively correlated with the inorganic mass fraction of the particles. Photochemical processing reduced the range of κ values to between 0.08 and 0.3. The changes in κ were driven by the photochemical production of secondary organic aerosol (SOA). SOA also contributed to growth of particles formed during nucleation events. Analysis of the nucleation mode particles enabled the first direct quantification of the hygroscopicity parameter κ for biomass burning SOA, which was on average 0.11, similar to values observed for biogenic SOA. Although initial CCN activity of biomass burning aerosol emissions are highly variable, after a few hours of photochemical processing κ converges to a value of 0.2 ± 0.1. Therefore, photochemical aging reduces the variability of biomass burning CCN κ, which should simplify analysis of the potential effects of biomass burning aerosol on climate.

scholarly journals Experimentally measured morphology of biomass burning aerosol and its impacts on CCN ability

2014 ◽  
Vol 14 (9) ◽  
pp. 12555-12589
Author(s):  
M. Giordano ◽  
C. Espinoza ◽  
A. Asa-Awuku
Keyword(s):  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Morphological Characteristics ◽  
Particle Morphology ◽  
Morphological Data ◽  
Environmental Research ◽  
Mass Analyzer ◽  
Condensation Nuclei ◽  
Biomass Burning Aerosol ◽  
Dynamic Shape

Abstract. This study examines the morphological properties of freshly emitted and atmospherically aged aerosols from biomass burning. The impacts of particle morphology assumptions on hygroscopic predictions are examined. Chamber experiments were conducted at the UC-Riverside Center for Environmental Research and Technology (CE-CERT) Atmospheric Processes Lab using two biomass fuel sources, manzanita and chamise. Morphological data was obtained through the use of an aerosol particle mass analyzer (APM), scanning mobility particle sizer (SMPS) system and transmission electron microscopy (TEM). Data from these instruments was used to calculate both a dynamic shape factor and a fractal-like dimension for the biomass burning emissions. This data was then used with κ-Köhler theory to adjust the calculated hygroscopicity for experimentally determined morphological characteristics of the aerosol. Laboratory measurement of biomass burning aerosol from two chaparral fuels show that particles are non-spherical with dynamic shape factors greater than 1.15 for aerosol sizes relevant to cloud condensation nuclei (CCN) activation. Accounting for particle morphology can shift the hygroscopicity parameter κ by 0.15 or more. To our knowledge, this work provides the first laboratory chamber measurements of morphological characteristics for biomass burning cloud condensation nuclei and provides experimental particle shape evidence to support the variation in reported hygroscopicities of the complex aerosol.

scholarly journals Experimentally measured morphology of biomass burning aerosol and its impacts on CCN ability

2015 ◽  
Vol 15 (4) ◽  
pp. 1807-1821 ◽  
Author(s):  
M. Giordano ◽  
C. Espinoza ◽  
A. Asa-Awuku
Keyword(s):  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Morphological Characteristics ◽  
Particle Morphology ◽  
Morphological Data ◽  
Environmental Research ◽  
Mass Analyzer ◽  
Condensation Nuclei ◽  
Biomass Burning Aerosol ◽  
Dynamic Shape

Abstract. This study examines the morphological properties of freshly emitted and atmospherically aged aerosols from biomass burning. The impacts of particle morphology assumptions on hygroscopic predictions are examined. Chamber experiments were conducted at the University of California, Riverside, Center for Environmental Research and Technology (CE-CERT) atmospheric processes lab using two biomass fuel sources: manzanita and chamise. Morphological data was obtained through the use of an aerosol particle mass analyzer (APM), scanning mobility particle sizer (SMPS) system and transmission electron microscope (TEM). Data from these instruments was used to calculate both a dynamic shape factor and a fractal-like dimension for the biomass burning emissions. This data was then used with κ-Köhler theory to adjust the calculated hygroscopicity for experimentally determined morphological characteristics of the aerosol. Laboratory measurement of biomass burning aerosol from two chaparral fuels show that particles are nonspherical with dynamic shape factors greater than 1.15 for aerosol sizes relevant to cloud condensation nuclei (CCN) activation. Accounting for particle morphology can shift the hygroscopicity parameter by 0.15 or more. To our knowledge, this work provides the first laboratory chamber measurements of morphological characteristics for biomass burning cloud condensation nuclei and provides experimental particle shape evidence to support the variation in reported hygroscopicities of the complex aerosol.

scholarly journals Long-term observations of cloud condensation nuclei in the Amazon rain forest – Part 2: Variability and characteristic differences under near-pristine, biomass burning, and long-range transport conditions

2017 ◽  
Author(s):  
Mira L. Pöhlker ◽  
Florian Ditas ◽  
Jorge Saturno ◽  
Thomas Klimach ◽  
Isabella Hrabě de Angelis ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Amazon Basin ◽  
Cloud Condensation Nuclei ◽  
Condensation Nuclei ◽  
Aerosol Cloud ◽  
Amazon Rain Forest ◽  
Depth Analysis ◽  
Modelling Studies ◽  
Original Time ◽  
Aerosol Emissions

Abstract. Size-resolved measurements of atmospheric aerosol and cloud condensation nuclei (CCN) concentrations and hygroscopicity were conducted at the remote Amazon Tall Tower Observatory (ATTO) in the central Amazon Basin over a full seasonal cycle (Mar 2014–Feb 2015). In a companion part 1 paper, we presented an in-depth CCN characterization based on annually as well as seasonally averaged time intervals and discuss different parametrization strategies to represent the Amazonian CCN cycling in modelling studies (M. Pöhlker et al., 2016b). The present part 2 study analyzes the aerosol and CCN variability in original time resolution and, thus, resolves aerosol advection and transformation for the following case studies, which represent the most characteristic states of the Amazonian atmosphere: 1. Near-pristine (NP) conditions, defined as the absence of detectable black carbon ( 90 %), and correspondingly low hygroscopicity levels (κAit = 0.14, κacc = 0.17). The BB CCN efficiency spectrum shows that the CCN population is highly sensitive to changes in S in the low S regime. 4. Mixed pollution conditions show the superposition of African (i.e., volcanic) and Amazonian (i.e., biomass burning) aerosol emissions during the dry season. The African aerosols showed a broad monomodal distribution (D = 130 nm, N = ~ 1300 cm−3), with very high sulfate fractions (20 %), and correspondingly high hygroscopicity (κAit = 0.14, κacc = 0.22). This was superimposed by fresh smoke from nearby fires with one strong mode (D = 113 nm, Nacc = ~ 2800 cm−3), an organic-dominated aerosol, and sharply decreased hygroscopicity (κAit = 0.10, κacc = 0.20). These conditions underline the rapidly changing pollution regimes with clear impacts on the aerosol and CCN properties. Overall, this study provides detailed insights into the CCN cycling in relation to aerosol-cloud interaction in the vulnerable and climate-relevant Amazon region. The detailed analysis of aerosol and CCN key properties and particularly the extracted CCN efficiency spectra with the associated fit parameters provide a basis for an in-depth analysis of aerosol-cloud interaction in the Amazon and beyond.

scholarly journals Cloud condensation nuclei activity of fresh primary and aged biomass burning aerosol

2012 ◽  
Vol 12 (3) ◽  
pp. 7521-7544 ◽  
Author(s):  
G. J. Engelhart ◽  
C. J. Hennigan ◽  
M. A. Miracolo ◽  
A. L. Robinson ◽  
S. N. Pandis
Keyword(s):  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Organic Aerosol ◽  
Condensation Nuclei ◽  
Hygroscopic Properties ◽  
A Value ◽  
Biomass Burning Aerosol ◽  
Photochemical Processing ◽  
Photochemical Aging ◽  
Aerosol Emissions

Abstract. We quantify the hygroscopic properties of particles freshly emitted from biomass burning and after several hours of photochemical aging in a smog chamber. Values of the hygroscopicity parameter, κ, were calculated from cloud condensation nuclei (CCN) measurements of emissions from combustion of 12 biomass fuels commonly burned in North American wildfires. Prior to photochemical aging, the κ of the fresh primary aerosol varied widely, between 0.06 (weakly hygroscopic) and 0.6 (highly hygroscopic). The hygroscopicity of the primary aerosol was positively correlated with the inorganic mass fraction of the particles. There was also a relationship between the hygroscopicity of the primary aerosol and the extent of oxygenation of the primary organic aerosol (POA), suggesting an influence of the POA composition on the primary aerosol hygroscopicity as well. Photochemical processing reduced the range of κ values to between 0.08 and 0.3. The changes in κ were driven by the photochemical production of secondary organic aerosol (SOA). SOA also contributed to growth of particles formed during nucleation events. Analysis of the nucleation mode particles enabled the first direct quantification of the hygroscopicity parameter κ for biomass burning SOA, which was on average 0.11, similar to values observed for biogenic SOA. Although initial CCN activity of biomass burning aerosol emissions are highly variable, after a few hours of photochemical processing κ converges to a value of 0.2 ± 0.1. Therefore, photochemical aging reduces the variability of biomass burning CCN, which should simplify analysis of the potential effects of biomass burning aerosol on climate.

scholarly journals Composition, size and cloud condensation nuclei activity of biomass burning aerosol from north Australian savannah fires

2016 ◽  
Author(s):  
Marc D. Mallet ◽  
Luke T. Cravigan ◽  
Andelija Milic ◽  
Joel Alroe ◽  
Zoran D. Ristovski ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Chemical Properties ◽  
Dry Season ◽  
Photochemical Oxidation ◽  
Research Station ◽  
Hygroscopic Growth ◽  
Condensation Nuclei ◽  
Trade Winds ◽  
Biomass Burning Aerosol

Abstract. The vast majority of Australia's fires occur in the tropical north of the continent during the dry season. These fires are a significant source of aerosol and cloud condensation nuclei (CCN) in the region, providing a unique opportunity to investigate the biomass burning aerosol (BBA) in the absence of other sources. CCN concentrations at 0.5 % supersaturation and aerosol size and chemical properties were measured at the Australian Tropical Atmospheric Research Station (ATARS) during June 2014. CCN concentrations reached over 104 cm−3 when frequent and close fires were burning; up to 45 times higher than periods with no fires. Both the size distribution and composition of BBA appeared to significantly influence CCN concentrations. A distinct diurnal trend in the proportion of BBA activating to cloud droplets was observed, with an activation ratio of 40 % ± 20 % during the night and 60 % ± 20 % during the day. BBA was, on average, less hygroscopic during the night (κ = 0.04 ± 0.03) than during the day (κ = 0.07 ± 0.05), with a maximum typically observed just before midday. Size-resolved composition of BBA showed that organics comprised a constant 90 % of the aerosol volume for aerodynamic diameters between 100 nm and 200 nm. The photochemical oxidation of organics led to an increase in the hygroscopic growth and an increase in daytime activation ratios. Modelled CCN concentrations assuming typical continental hygroscopicities produced very large overestimations of up to 200 %. Smaller, but still significant over predictions up to ~100 % were observed using AMS and H-TDMA derived hygroscopicities as well as campaign night and day averages. The largest estimations in every case occurred during the night when the small variations in very weakly hygroscopic species corresponded to large variations in the activation diameters. Trade winds carry the smoke generated from these fires over the Timor Sea where aerosol-cloud interactions are likely to be sensitive to changes in CCN concentrations, perturbing cloud albedo and lifetime. Dry season fires in north Australia are therefore potentially very important in cloud processes in this region.

scholarly journals Composition, size and cloud condensation nuclei activity of biomass burning aerosol from northern Australian savannah fires

2017 ◽  
Vol 17 (5) ◽  
pp. 3605-3617 ◽  
Author(s):  
Marc D. Mallet ◽  
Luke T. Cravigan ◽  
Andelija Milic ◽  
Joel Alroe ◽  
Zoran D. Ristovski ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Chemical Properties ◽  
Dry Season ◽  
Photochemical Oxidation ◽  
Research Station ◽  
Hygroscopic Growth ◽  
Condensation Nuclei ◽  
Trade Winds ◽  
Biomass Burning Aerosol

Abstract. The vast majority of Australia's fires occur in the tropical north of the continent during the dry season. These fires are a significant source of aerosol and cloud condensation nuclei (CCN) in the region, providing a unique opportunity to investigate the biomass burning aerosol (BBA) in the absence of other sources. CCN concentrations at 0.5 % supersaturation and aerosol size and chemical properties were measured at the Australian Tropical Atmospheric Research Station (ATARS) during June 2014. CCN concentrations reached over 104 cm−3 when frequent and close fires were burning – up to 45 times higher than periods with no fires. Both the size distribution and composition of BBA appeared to significantly influence CCN concentrations. A distinct diurnal trend in the proportion of BBA activating to cloud droplets was observed, with an activation ratio of 40 ± 20 % during the night and 60 ± 20 % during the day. BBA was, on average, less hygroscopic during the night (κ = 0. 04 ± 0.03) than during the day (κ =  0.07 ± 0.05), with a maximum typically observed just before midday. Size-resolved composition of BBA showed that organics comprised a constant 90 % of the aerosol volume for aerodynamic diameters between 100 and 200 nm. While this suggests that the photochemical oxidation of organics led to an increase in the hygroscopic growth and an increase in daytime activation ratios, it does not explain the decrease in hygroscopicity after midday. Modelled CCN concentrations assuming typical continental hygroscopicities produced very large overestimations of up to 200 %. Smaller, but still significant, overpredictions up to  ∼  100 % were observed using aerosol mass spectrometer (AMS)- and hygroscopicity tandem differential mobility analyser (H-TDMA)-derived hygroscopicities as well as campaign night and day averages. The largest estimations in every case occurred during the night, when the small variations in very weakly hygroscopic species corresponded to large variations in the activation diameters. Trade winds carry the smoke generated from these fires over the Timor Sea, where aerosol–cloud interactions are likely to be sensitive to changes in CCN concentrations, perturbing cloud albedo and lifetime. Dry season fires in northern Australia are therefore potentially very important in cloud processes in this region.

Sign in / Sign up

Export Citation Format

Share Document