Expected impact of an aged biomass burning aerosol on cloud condensation nuclei and cloud droplet concentrations

2006 ◽  
Vol 111 (D22) ◽  
Author(s):  
Yong Seob Lee ◽  
Don R. Collins ◽  
Runjun Li ◽  
Kenneth P. Bowman ◽  
Graham Feingold
Keyword(s):  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Condensation Nuclei ◽  
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 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.

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