scholarly journals Effects of film-forming compounds on the growth of giant cloud condensation nuclei: Implications for cloud microphysics and the aerosol indirect effect

2004 ◽  
Vol 109 (D20) ◽  
Author(s):  
Jeessy Medina
Keyword(s):  
Indirect Effect ◽  
Cloud Condensation Nuclei ◽  
Cloud Microphysics ◽  
Condensation Nuclei ◽  
Aerosol Indirect Effect ◽  
Film Forming

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 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 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 Remote sensing the vertical profile of cloud droplet effective radius, thermodynamic phase, and temperature

2011 ◽  
Vol 11 (18) ◽  
pp. 9485-9501 ◽  
Author(s):  
J. V. Martins ◽  
A. Marshak ◽  
L. A. Remer ◽  
D. Rosenfeld ◽  
Y. J. Kaufman ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Energy Balance ◽  
Brightness Temperature ◽  
Vertical Profile ◽  
Water Cycle ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Cloud Microphysics ◽  
Condensation Nuclei ◽  
Thermodynamic Phase

Abstract. Cloud-aerosol interaction is a key issue in the climate system, affecting the water cycle, the weather, and the total energy balance including the spatial and temporal distribution of latent heat release. Information on the vertical distribution of cloud droplet microphysics and thermodynamic phase as a function of temperature or height, can be correlated with details of the aerosol field to provide insight on how these particles are affecting cloud properties and their consequences to cloud lifetime, precipitation, water cycle, and general energy balance. Unfortunately, today's experimental methods still lack the observational tools that can characterize the true evolution of the cloud microphysical, spatial and temporal structure in the cloud droplet scale, and then link these characteristics to environmental factors and properties of the cloud condensation nuclei. Here we propose and demonstrate a new experimental approach (the cloud scanner instrument) that provides the microphysical information missed in current experiments and remote sensing options. Cloud scanner measurements can be performed from aircraft, ground, or satellite by scanning the side of the clouds from the base to the top, providing us with the unique opportunity of obtaining snapshots of the cloud droplet microphysical and thermodynamic states as a function of height and brightness temperature in clouds at several development stages. The brightness temperature profile of the cloud side can be directly associated with the thermodynamic phase of the droplets to provide information on the glaciation temperature as a function of different ambient conditions, aerosol concentration, and type. An aircraft prototype of the cloud scanner was built and flew in a field campaign in Brazil. The CLAIM-3D (3-Dimensional Cloud Aerosol Interaction Mission) satellite concept proposed here combines several techniques to simultaneously measure the vertical profile of cloud microphysics, thermodynamic phase, brightness temperature, and aerosol amount and type in the neighborhood of the clouds. The wide wavelength range, and the use of multi-angle polarization measurements proposed for this mission allow us to estimate the availability and characteristics of aerosol particles acting as cloud condensation nuclei, and their effects on the cloud microphysical structure. These results can provide unprecedented details on the response of cloud droplet microphysics to natural and anthropogenic aerosols in the size scale where the interaction really happens.

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.

Effects of Number Concentration of Cloud Condensation Nuclei on Moist Convection Formation

2021 ◽  
Author(s):  
Yoshiaki Miyamoto
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Time Scale ◽  
Numerical Experiments ◽  
Cloud Condensation Nuclei ◽  
Cloud Microphysics ◽  
Number Concentration ◽  
Moist Convection ◽  
Condensation Nuclei

AbstractWe examined the sensitivity of the formation of moist convection to the number of aerosols that serve as cloud condensation nuclei (CCN) based on a set of numerical experiments using a nonhydrostatic model with a bin cloud microphysics model. Additionally, a linear stability analysis for an air parcel incorporating effects of the CCN number concentration (NCCN) has been conducted to further demonstrate the findings in numerical experiments. The results of the numerical experiments show that moist convection does not form when NCCN ≤ 10 cm−3. The sensitivity to NCCN can be divided into three regimes: when NCCN ≤ 10 cm−3, convection does not form or not fully develop; when 1 ≤ NCCN ≤ 102 cm−3, maximum vertical velocity increases with NCCN; and when NCCN ≥ 102 cm−3, the intensity of convection does not largely depend on NCCN. We demonstrate that the main reason convection does not form under environments with a small NCCN is that the time scale for condensation is longer than that to change environmental conditions. Given a supersaturated environment, fewer droplets form when NCCN is small and the size of droplets is potentially large. Consequently, the amount of latent heating is limited and the air parcel cannot obtain buoyancy within a reasonable time scale. Linear stability analysis using a parcel model considering the effect of NCCN without ice-phase processes shows unstable and stable regimes as a function of the number of droplets. The analytically obtained critical droplet number for the convection formation well corresponds to the minimum NCCN beyond which convection forms in the present numerical experiments.

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.

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