scholarly journals Global cloud condensation nuclei influenced by carbonaceous combustion aerosol

2011 ◽  
Vol 11 (17) ◽  
pp. 9067-9087 ◽  
Author(s):  
D. V. Spracklen ◽  
K. S. Carslaw ◽  
U. Pöschl ◽  
A. Rap ◽  
P. M. Forster
Keyword(s):  
Black Carbon ◽  
Carbon Emissions ◽  
Indirect Effect ◽  
Fossil Fuel ◽  
Cloud Condensation Nuclei ◽  
Pollution Sources ◽  
Aerosol Indirect Effect ◽  
Cloud Albedo ◽  
Combustion Particles ◽  
Global Mean

Abstract. Black carbon in carbonaceous combustion aerosol warms the climate by absorbing solar radiation, meaning reductions in black carbon emissions are often perceived as an attractive global warming mitigation option. However, carbonaceous combustion aerosol can also act as cloud condensation nuclei (CCN) so they also cool the climate by increasing cloud albedo. The net radiative effect of carbonaceous combustion aerosol is uncertain because their contribution to CCN has not been evaluated on the global scale. By combining extensive observations of CCN concentrations with the GLOMAP global aerosol model, we find that the model is biased low (normalised mean bias = −77 %) unless carbonaceous combustion aerosol act as CCN. We show that carbonaceous combustion aerosol accounts for more than half (52–64 %) of global CCN with the range due to uncertainty in the emitted size distribution of carbonaceous combustion particles. The model predicts that wildfire and pollution (fossil fuel and biofuel) carbonaceous combustion aerosol causes a global mean cloud albedo aerosol indirect effect of −0.34 W m−2, with stronger cooling if we assume smaller particle emission size. We calculate that carbonaceous combustion aerosol from pollution sources cause a global mean aerosol indirect effect of −0.23 W m−2. The small size of carbonaceous combustion particles from fossil fuel sources means that whilst pollution sources account for only one-third of the emitted mass they cause two-thirds of the cloud albedo aerosol indirect effect that is due to carbonaceous combustion aerosol. This cooling effect must be accounted for, along with other cloud effects not studied here, to ensure that black carbon emissions controls that reduce the high number concentrations of fossil fuel particles have the desired net effect on climate.

scholarly journals Global cloud condensation nuclei influenced by carbonaceous combustion aerosol

2011 ◽  
Vol 11 (3) ◽  
pp. 6999-7044 ◽  
Author(s):  
D. V. Spracklen ◽  
K. S. Carslaw ◽  
U. Pöschl ◽  
A. Rap ◽  
P. M. Forster
Keyword(s):  
Black Carbon ◽  
Carbon Emissions ◽  
Indirect Effect ◽  
Cloud Condensation Nuclei ◽  
Pollution Sources ◽  
Condensation Nuclei ◽  
Aerosol Indirect Effect ◽  
Aerosol Model ◽  
Cloud Albedo ◽  
Global Mean

Abstract. Black carbon in carbonaceous combustion aerosol warms the climate by absorbing solar radiation, meaning reductions in black carbon emissions are often perceived as an attractive global warming mitigation option. However, carbonaceous combustion aerosol can also act as cloud condensation nuclei (particles upon which cloud drops form) so they also cool the climate by increasing cloud albedo. The net radiative effect of carbonaceous combustion aerosol is uncertain because their contribution to cloud drops has not been evaluated on the global scale. By combining extensive observations of cloud condensation nuclei concentrations and a global aerosol model, we show that carbonaceous combustion aerosol accounts for more than half of global cloud condensation nuclei. The evaluated model predicts that wildfire and pollution (fossil fuel and biofuel) carbonaceous combustion aerosol causes a global mean aerosol indirect effect of −0.34 W m−2 due to changes in cloud albedo, with pollution sources alone causing a global mean aerosol indirect effect of −0.23 W m−2. The small size of carbonaceous combustion particles from pollution sources means that whilst they account for only one-third of the emitted mass from these sources they cause two-thirds of the cloud albedo indirect effect that is due to carbonaceous combustion aerosol. This cooling effect must be accounted for to ensure that black carbon emissions controls that reduce the high number concentrations of small pollution particles have the desired net effect on climate.

scholarly journals Weak global sensitivity of cloud condensation nuclei and the aerosol indirect effect to Criegee + SO<sub>2</sub> chemistry

2013 ◽  
Vol 13 (6) ◽  
pp. 3163-3176 ◽  
Author(s):  
J. R. Pierce ◽  
M. J. Evans ◽  
C. E. Scott ◽  
S. D. D'Andrea ◽  
D. K. Farmer ◽  
...  
Keyword(s):  
Boundary Layers ◽  
Indirect Effect ◽  
Cloud Condensation Nuclei ◽  
Chemical Mechanism ◽  
Model Parameters ◽  
Condensation Nuclei ◽  
Aerosol Indirect Effect ◽  
Global Sensitivity ◽  
Cloud Albedo ◽  
The Impact

Abstract. H2SO4 vapor is important for the nucleation of atmospheric aerosols and the growth of ultrafine particles to cloud condensation nuclei (CCN) sizes with important roles in the global aerosol budget and hence planetary radiative forcing. Recent studies have found that reactions of stabilized Criegee intermediates (CIs, formed from the ozonolysis of alkenes) with SO2 may be an important source of H2SO4 that has been missing from atmospheric aerosol models. For the first time in a global model, we investigate the impact of this new source of H2SO4 in the atmosphere. We use the chemical transport model, GEOS-Chem, with the online aerosol microphysics module, TOMAS, to estimate the possible impact of CIs on present-day H2SO4, CCN, and the cloud-albedo aerosol indirect effect (AIE). We extend the standard GEOS-Chem chemistry with CI-forming reactions (ozonolysis of isoprene, methyl vinyl ketone, methacrolein, propene, and monoterpenes) from the Master Chemical Mechanism. Using a fast rate constant for CI+SO2, we find that the addition of this chemistry increases the global production of H2SO4 by 4%. H2SO4 concentrations increase by over 100% in forested tropical boundary layers and by over 10–25% in forested NH boundary layers (up to 100% in July) due to CI+SO2 chemistry, but the change is generally negligible elsewhere. The predicted changes in CCN were strongly dampened to the CI+SO2 changes in H2SO4 in some regions: less than 15% in tropical forests and less than 2% in most mid-latitude locations. The global-mean CCN change was less than 1% both in the boundary layer and the free troposphere. The associated cloud-albedo AIE change was less than 0.03 W m−2. The model global sensitivity of CCN and the AIE to CI+SO2 chemistry is significantly (approximately one order-of-magnitude) smaller than the sensitivity of CCN and AIE to other uncertain model inputs, such as nucleation mechanisms, primary emissions, SOA (secondary organic aerosol) and deposition. Similarly, comparisons to size-distribution measurements show that uncertainties in other model parameters dominate model biases in the model-predicted size distributions. We conclude that improvement in the modeled CI+SO2 chemistry would not likely lead to significant improvements in present-day CCN and AIE predictions.

scholarly journals Weak sensitivity of cloud condensation nuclei and the aerosol indirect effect to Criegee + SO<sub>2</sub> chemistry

2012 ◽  
Vol 12 (12) ◽  
pp. 33127-33163 ◽  
Author(s):  
J. R. Pierce ◽  
M. J. Evans ◽  
C. E. Scott ◽  
S. D. D'Andrea ◽  
D. K. Farmer ◽  
...  
Keyword(s):  
Boundary Layers ◽  
Indirect Effect ◽  
Ultrafine Particles ◽  
Transport Model ◽  
Cloud Condensation Nuclei ◽  
Chemical Mechanism ◽  
Model Parameters ◽  
Condensation Nuclei ◽  
Aerosol Indirect Effect ◽  
Cloud Albedo

Abstract. H2SO4 vapor is important for the nucleation of atmospheric aerosols and the growth of ultrafine particles to cloud condensation nuclei (CCN) sizes. Recent studies have found that reactions of stabilized Criegee intermediates (CIs, formed from the ozonolysis of alkenes) with SO2 may be an important source of H2SO4 that has been missing from atmospheric aerosol models. In this paper, we use the chemical transport model, GEOS-Chem, with the online aerosol microphysics module, TOMAS, to estimate the possible impact of CIs on present-day H2SO4, CCN, and the cloud-albedo aerosol indirect effect (AIE). We extend the standard GEOS-Chem chemistry with CI-forming reactions (ozonolysis of isoprene, methyl vinyl ketone, methacrolein, propene, and monoterpenes) from the Master Chemical Mechanism. Using a fast rate constant for CI+SO2, we find that the addition of this chemistry increases the global production of H2SO4 by 4%. H2SO4 concentrations increase by over 100% in forested tropical boundary layers and by over 10–25% in forested NH boundary layers (up to 100% in July) due to CI + SO2 chemistry, but the change is generally negligible elsewhere. The predicted changed in CCN were strongly dampened to the CI + SO2 changes in H2SO4 in these regions: less than 15% in tropical forests and less than 2% in most mid-latitude locations. The global-mean CCN change was less than 1% both in the boundary layer and the free troposphere. The associated cloud-albedo AIE change was less than 0.03 W m−2. The model global sensitivity of CCN and the AIE to CI + SO2 chemistry is significantly (approximately one order-of-magnitude) smaller than the sensitivity of CCN and AIE to other uncertain model inputs, such as nucleation mechanisms, primary emissions, SOA and deposition. Similarly, comparisons to size-distribution measurements show that uncertainties in other model parameters dominate model biases in the model-predicted size distributions. We conclude that improvement in the modeled CI + SO2 chemistry would not likely to lead to significant improvements in present-day CCN and AIE predictions.

scholarly journals Black carbon in the atmosphere and snow, from pre-industrial times until present

2011 ◽  
Vol 11 (14) ◽  
pp. 6809-6836 ◽  
Author(s):  
R. B. Skeie ◽  
T. Berntsen ◽  
G. Myhre ◽  
C. A. Pedersen ◽  
J. Ström ◽  
...  
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
Fossil Fuel ◽  
The Arctic ◽  
Slight Reduction ◽  
Snow Albedo ◽  
Aerosol Effect ◽  
Albedo Effect ◽  
Concentration Changes ◽  
Global Mean

Abstract. The distribution of black carbon (BC) in the atmosphere and the deposition of BC on snow surfaces since pre-industrial time until present are modelled with the Oslo CTM2 model. The model results are compared with observations including recent measurements of BC in snow in the Arctic. The global mean burden of BC from fossil fuel and biofuel sources increased during two periods. The first period, until 1920, is related to increases in emissions in North America and Europe, and the last period after 1970 are related mainly to increasing emissions in East Asia. Although the global burden of BC from fossil fuel and biofuel increases, in the Arctic the maximum atmospheric BC burden as well as in the snow was reached in 1960s, with a slight reduction thereafter. The global mean burden of BC from open biomass burning sources has not changed significantly since 1900. With current inventories of emissions from open biomass sources, the modelled burden of BC in snow and in the atmosphere north of 65° N is small compared to the BC burden of fossil fuel and biofuel origin. From the concentration changes radiative forcing time series due to the direct aerosol effect as well as the snow-albedo effect is calculated for BC from fossil fuel and biofuel. The calculated radiative forcing in 2000 for the direct aerosol effect is 0.35 W m−2 and for the snow-albedo effect 0.016 W m−2 in this study. Due to a southward shift in the emissions there is an increase in the lifetime of BC as well as an increase in normalized radiative forcing, giving a change in forcing per unit of emissions of 26 % since 1950.

scholarly journals Exploring the First Aerosol Indirect Effect over the Maritime Continent Using a Ten-Year Collocated MODIS, CALIOP, and Model Dataset

2018 ◽  
Author(s):  
Alexa D. Ross ◽  
Robert E. Holz ◽  
Gregory Quinn ◽  
Jeffrey S. Reid ◽  
Peng Xian ◽  
...  
Keyword(s):  
Indirect Effect ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Effective Radius ◽  
Satellite Observations ◽  
Orthogonal Polarization ◽  
High Background ◽  
Aerosol Indirect Effect ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Complex Relationships

Abstract. Satellite observations and model simulations cannot, by themselves, give full insight into the complex relationships between aerosols and clouds. This is especially the case over the greater Southeast Asia, an area that is particularly sensitive to changes in precipitation yet possesses some of the world’s largest observability and predictability challenges. We present a new collocated dataset that combines satellite observations from Aqua's Moderate-resolution Imaging Spectroradiometer (MODIS) and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) with the Navy Aerosol Analysis and Prediction System (NAAPS). The dataset is designed with the capability to investigate aerosol-cloud relationships and provides coincident and vertically resolved cloud and aerosol observations for a ten-year period. Using model reanalysis aerosol fields from the NAAPS and coincident cloud liquid effective radius retrievals from MODIS (removing cirrus contamination using CALIOP), we investigate the first aerosol indirect effect. We find overall that as expected, aerosol loading anti-correlates with cloud effective radius, with maximum sensitivity in cumulous mediocris clouds with heights in the 3–4.5 km level. The highest susceptibility in droplet effective radius to modeled perturbations in particle concentrations were found in the more remote regions of the western Pacific Ocean and Indian Ocean. Conversely, there was much less variability in cloud droplet size near emission sources over both land and water. We hypothesize this is suggestive of a high background aerosol population already saturating the cloud condensation nuclei budget.

scholarly journals The aerosol radiative effects of uncontrolled combustion of domestic waste

2016 ◽  
Vol 16 (11) ◽  
pp. 6771-6784 ◽  
Author(s):  
John K. Kodros ◽  
Rachel Cucinotta ◽  
David A. Ridley ◽  
Christine Wiedinmyer ◽  
Jeffrey R. Pierce
Keyword(s):  
Indirect Effect ◽  
Transport Model ◽  
Radiative Effect ◽  
Chemical Transport Model ◽  
Domestic Waste ◽  
Emissions Inventory ◽  
Aerosol Indirect Effect ◽  
Waste Combustion ◽  
Cloud Albedo ◽  
Aerosol Radiative

Abstract. Open, uncontrolled combustion of domestic waste is a potentially significant source of aerosol; however, this aerosol source is not generally included in many global emissions inventories. To provide a first estimate of the aerosol radiative impacts from domestic-waste combustion, we incorporate the Wiedinmyer et al. (2014) emissions inventory into GEOS-Chem-TOMAS, a global chemical-transport model with online aerosol microphysics. We find domestic-waste combustion increases global-mean black carbon and organic aerosol concentrations by 8 and 6 %, respectively, and by greater than 40 % in some regions. Due to uncertainties regarding aerosol optical properties, we estimate the globally averaged aerosol direct radiative effect to range from −5 to −20 mW m−2; however, this range increases from −40 to +4 mW m−2 when we consider uncertainties in emission mass and size distribution. In some regions with significant waste combustion, such as India and China, the aerosol direct radiative effect may exceed −0.4 W m−2. Similarly, we estimate a cloud-albedo aerosol indirect effect of −13 mW m−2, with a range of −4 to −49 mW m−2 due to emission uncertainties. In the regions with significant waste combustion, the cloud-albedo aerosol indirect effect may exceed −0.4 W m−2.

scholarly journals Coincidence Errors in a Cloud Droplet Probe (CDP) and a Cloud and Aerosol Spectrometer (CAS), and the Improved Performance of a Modified CDP

2012 ◽  
Vol 29 (10) ◽  
pp. 1532-1541 ◽  
Author(s):  
Sara Lance
Keyword(s):  
Systematic Error ◽  
Indirect Effect ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Current Paper ◽  
Aerosol Indirect Effect ◽  
Improved Performance ◽  
Measurement Artifact ◽  
The Relationship

Abstract Central to the aerosol indirect effect on climate is the relationship between cloud droplet concentrations Nd and cloud condensation nuclei (CCN) concentrations. There are valid reasons to expect a sublinear relationship between measured Nd and CCN, and such relationships have been observed for clouds in a variety of locations. However, a measurement artifact known as “coincidence” can also produce a sublinear trend. The current paper shows that two commonly used instruments, the cloud droplet probe (CDP) and the cloud and aerosol spectrometer (CAS), can be subject to significantly greater coincidence errors than are typically recognized, with an undercounting bias of at least 27% and an oversizing bias of 20%–30% on average at Nd = 500 cm−3, and with an undercounting bias of as much as 44% at Nd = 1000 cm−3. This type of systematic error may have serious implications for interpretation of in situ cloud observations. It is shown that a simple optical modification of the CDP dramatically reduces oversizing and undercounting biases due to coincidence. Guidance is provided for diagnosing coincidence errors in CAS and CDP instruments.

scholarly journals Black carbon in the atmosphere and snow, from pre-industrial times until present

2011 ◽  
Vol 11 (3) ◽  
pp. 7469-7534 ◽  
Author(s):  
R. B. Skeie ◽  
T. Berntsen ◽  
G. Myhre ◽  
C. A. Pedersen ◽  
J. Ström ◽  
...  
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
Fossil Fuel ◽  
The Arctic ◽  
Slight Reduction ◽  
Snow Albedo ◽  
Aerosol Effect ◽  
Albedo Effect ◽  
Concentration Changes ◽  
Global Mean

Abstract. The distribution of black carbon (BC) in the atmosphere and the deposition of BC on snow surfaces since pre-industrial time until present are modelled with the Oslo CTM2 model. The model results are compared with observations including recent measurements of BC in snow in the Arctic. The global mean burden of BC from fossil fuel and biofuel sources increased during two periods. The first period, until 1920, is related to increases in emissions in North America and Europe, and the last period after 1970 are related mainly to increasing emissions in East Asia. Although the global burden of BC from fossil fuel and biofuel increases, in the Arctic the maximum atmospheric BC burden as well as in the snow was reached in 1960s, with a slight reduction thereafter. The global mean burden of BC from open biomass burning sources has not changed significantly since 1900. With current inventories of emissions from open biomass sources, the modelled burden of BC in snow and in the atmosphere north of 65° N is small compared to the BC burden of fossil fuel and biofuel origin. From the concentration changes radiative forcing time series due to the direct aerosol effect as well as the snow-albedo effect is calculated for BC from fossil fuel and biofuel. The calculated radiative forcing in 2000 for the direct aerosol effect is 0.35 W m−2 and for the snow-albedo effect 0.016 W m−2. Due to a southward shift in the emissions there is an increase in the lifetime of BC as well as an increase in normalized radiative forcing, giving a change in forcing per unit of emissions of 26% since 1950.

scholarly journals The aerosol radiative effects of uncontrolled combustion of domestic waste

2016 ◽  
Author(s):  
John K. Kodros ◽  
Rachel Cucinotta ◽  
David A. Ridley ◽  
Christine Wiedinmyer ◽  
Jeffrey R. Pierce
Keyword(s):  
Indirect Effect ◽  
Transport Model ◽  
Radiative Effect ◽  
Chemical Transport Model ◽  
Domestic Waste ◽  
Emissions Inventory ◽  
Aerosol Indirect Effect ◽  
Waste Combustion ◽  
Cloud Albedo ◽  
Aerosol Radiative

Abstract. Open, uncontrolled combustion of domestic waste is a potentially significant source of aerosol; however, this aerosol source is not generally included in many global emissions inventories. To provide a first estimate of the aerosol radiative impacts from domestic-waste combustion, we incorporate the Wiedinmyer et al. (2014) emissions inventory into GEOS-Chem-TOMAS, a global chemical-transport model with online aerosol microphysics. We find domestic-waste combustion increases global-mean black carbon and organic aerosol concentrations by 8 % and 6 %, respectively, and by greater than 40 % in some regions. Due to uncertainties regarding aerosol optical properties, we estimate the globally averaged aerosol direct radiative effect to range from −5 mW m−2 to −20 mW m−2; however, this range increases to −40 mW m−2 to &amp;plus;4 mW m−2 when we consider uncertainties in emission mass and size distribution. In some regions with significant waste combustion, such as India and China, the aerosol direct radiative effect may exceed −0.4 W m−2. Similarly, we estimate a cloud-albedo aerosol indirect effect of −13 mW m−2, with a range of −4 mW m−2 to −49 mW m−2 due to emission uncertainties. In the regions with significant waste combustion, the cloud-albedo aerosol indirect effect may exceed −0.4 W m−2.

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