scholarly journals Sensitivity of global cloud condensation nuclei concentrations to primary sulfate emission parameterizations

2011 ◽  
Vol 11 (5) ◽  
pp. 1949-1959 ◽  
Author(s):  
G. Luo ◽  
F. Yu
Keyword(s):  
Boundary Layer ◽  
Compensation Effect ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Nucleation And Growth ◽  
Ambient Atmosphere ◽  
Condensation Nuclei ◽  
Growth Processes ◽  
Particle Properties ◽  
The Impact

Abstract. The impact of primary sulfate emissions on cloud condensation nuclei (CCN) concentrations, one of the major uncertainties in global CCN predictions, depends on the fraction of sulfur mass emitted as primary sulfate particles (fsulfate), the fraction of primary sulfate mass distributed into the nucleation mode particles (fnucl), and the nucleation and growth processes in the ambient atmosphere. Here, we use a global size-resolved aerosol microphysics model recently developed to study how the different parameterizations of primary sulfate emission affect particle properties and CCN abundance. Different from previous studies, we use the ion-mediated nucleation scheme to simulate tropospheric particle formation. The kinetic condensation of low volatile secondary organic gas (SOG) (in addition to H2SO4 gas) on nucleated particles is calculated based on our new scheme that considers the SOG volatility changes arising from the oxidation aging. Our simulations show a compensation effect of nucleation to primary sulfate emission. We find that the change of fnucl from 5% to 15% has a more significant impact on the simulated particle number budget than that of fsulfate within the range of 2.5–5%. Based on our model configurations, an increase of fsulfate from 0% to 2.5% (with fnucl = 5%) does not improve the agreement between simulated and observed annual mean number concentrations of particles >10 nm at 21 stations but further increase of either fsulfate from 2.5% to 5% (with fnucl = 5%) or fnucl from 5% to 15% (with fsulfate = 2.5%) substantially deteriorates the agreement. For fsulfate of 2.5%–5% and fnucl of 5%, our simulations indicate that the global CCN at supersaturation of 0.2% increases by 8–11% in the boundary layer and 3–5% in the whole troposphere (compared to the case with fsulfate=0).

scholarly journals Sensitivity of global cloud condensation nuclei concentrations to primary sulfate emissions parameterizations

2010 ◽  
Vol 10 (11) ◽  
pp. 27695-27723
Author(s):  
G. Luo ◽  
F. Yu
Keyword(s):  
Boundary Layer ◽  
Growth Process ◽  
Compensation Effect ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Nucleation And Growth ◽  
Ambient Atmosphere ◽  
Condensation Nuclei ◽  
Particle Properties ◽  
The Impact

Abstract. The impact of primary sulfate emissions on cloud condensation nuclei (CCN) concentrations, one of the major uncertainties in global CCN predictions, depends on the fraction of sulfur mass emitted as primary sulfate particles (fsulfate), the fraction of primary sulfate mass distributed into the nucleation mode particles (fnucl), and the nucleation and growth process in the ambient atmosphere. Here, we use a global size-resolved aerosol microphysics model recently developed to study how the different parameterizations of primary sulfate emission affect particle properties and CCN abundance. Different from previous studies, we use the ion-mediated nucleation scheme to calculate tropospheric particle formation and explicitly simulate the condensation of low volatile secondary organic gas (in addition to H2SO4 gas) on nucleated particles. Our simulations show a compensation effect of nucleation to primary sulfate emission. We find that the change of fnucl from 5% to 15% has a more significant impact on the simulated particle number budget than that of fsulfate within the range of 2.5–5%. An increase of fsulfate from 0% to 2.5% (with fnucl = 5%) does not improve the agreement between simulated and observed annual mean number concentrations of particles >10 nm at 21 stations but further increase of either fsulfate from 2.5% to 5% (with fnucl = 5%) or fnucl from 5% to 15% (with fsulfate = 2.5%) substantially deteriorates the agreement. For fsulfate of 2.5%–5% and fnucl of 5%, our simulations indicate that the global CCN at supersaturation of 0.2 increases by 8–11% in the boundary layer and 3–5% in the whole troposphere (compared to the case with fsulfate = 0). Our derived impact of primary sulfate emission on global CCN abundance is about a factor of ∼3–7 smaller than those found in previous studies.

scholarly journals The impact of the 1783–1784 AD Laki eruption on global aerosol formation processes and cloud condensation nuclei

2010 ◽  
Vol 10 (2) ◽  
pp. 3189-3228
Author(s):  
A. Schmidt ◽  
K. S. Carslaw ◽  
G. W. Mann ◽  
B. M. Wilson ◽  
T. J. Breider ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Northern Hemisphere ◽  
General Circulation ◽  
Cloud Condensation Nuclei ◽  
General Circulation Models ◽  
Aerosol Formation ◽  
Condensation Nuclei ◽  
Upper Troposphere ◽  
Microphysical Processes ◽  
The Impact

Abstract. The 1783–1784 AD Laki flood lava eruption commenced on 8 June 1783 and released 122 Tg of sulphur dioxide gas over the course of 8 months into the upper troposphere and lower stratosphere above Iceland. Previous studies have examined the impact of the Laki eruption on sulphate aerosol and climate using general circulation models. Here, we study the impact on aerosol microphysical processes, including the nucleation of new particles and their growth to cloud condensation nuclei (CCN) using a comprehensive Global Model of Aerosol Processes (GLOMAP). Total particle concentrations in the free troposphere increase by a factor ~16 over large parts of the Northern Hemisphere in the 3 months following the onset of the eruption. Particle concentrations in the boundary layer increase by a factor 2 to 5 in regions as far away as North America, the Middle East and Asia due to long-range transport of nucleated particles. CCN concentrations (at 0.22% supersaturation) increase by a factor 65 in the upper troposphere with maximum changes in 3-month zonal mean concentrations of ~1400 cm−3 at high northern latitudes. 3-month zonal mean CCN concentrations in the boundary layer at the latitude of the eruption increase by up to a factor 26, and averaged over the Northern Hemisphere, the eruption caused a factor 4 increase in CCN concentrations at low-level cloud altitude. The simulations show that the Laki eruption would have completely dominated as a source of CCN in the pre-industrial atmosphere. The model also suggests an impact of the eruption in the Southern Hemisphere, where CCN concentrations are increased by up to a factor 1.4 at 20° S. Our model simulations suggest that the impact of an equivalent wintertime eruption on upper tropospheric CCN concentrations is only about one-third of that of a summertime eruption. The simulations show that the microphysical processes leading to the growth of particles to CCN sizes are fundamentally different after an eruption when compared to the unperturbed atmosphere, underlining the importance of using a fully coupled microphysics model when studying long-lasting, high-latitude eruptions.

scholarly journals Preconditioning of overcast-to-broken cloud transitions by riming in marine cold air outbreaks

2021 ◽  
Vol 21 (15) ◽  
pp. 12049-12067
Author(s):  
Florian Tornow ◽  
Andrew S. Ackerman ◽  
Ann M. Fridlind
Keyword(s):  
Boundary Layer ◽  
Liquid Water ◽  
Cloud Condensation Nuclei ◽  
Mixed Phase ◽  
Climate Feedback ◽  
Condensation Nuclei ◽  
Cold Air ◽  
Ice Particles ◽  
The Impact ◽  
Cold Air Outbreaks

Abstract. Marine cold air outbreaks (CAOs) commonly form overcast cloud decks that transition into broken cloud fields downwind, dramatically altering the local radiation budget. In this study, we investigate the impact of frozen hydrometeors on these transitions. We focus on a CAO case in the NW Atlantic, the location of the multi-year flight campaign ACTIVATE (Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment). We use MERRA-2 (Modern-Era Retrospective analysis for Research and Applications, version 2) reanalysis fields to drive large eddy simulations with mixed-phase two-moment microphysics in a Lagrangian framework. We find that transitions are triggered by substantial rain (rainwater paths >25 g m−2), and only simulations that allow for aerosol depletion result in sustained breakups, as observed. Using a range of diagnostic ice nucleating particle concentrations, Ninp, we find that increasing ice progressively accelerates transitions, thus abbreviating the overcast state. Ice particles affect the cloud-topped boundary layer evolution, primarily through riming-related processes prior to substantial rain, leading to (1) a reduction in cloud liquid water, (2) early consumption of cloud condensation nuclei, and (3) early and light precipitation cooling and moistening below cloud. We refer to these three effects collectively as “preconditioning by riming”. Greater boundary layer aerosol concentrations available as cloud condensation nuclei (CCN) delay the onset of substantial rain. However, cloud breakup and low CCN concentration final stages are found to be inevitable in this case, due, primarily, to liquid water path buildup. An ice-modulated cloud transition speed suggests the possibility of a negative cloud–climate feedback. To address prevailing uncertainties in the model representation of mixed-phase processes, the magnitude of ice formation and riming impacts and, thereby, the strength of an associated negative cloud–climate feedback process, requires further observational evaluation by targeting riming hot spots with in situ imaging probes that allow for both the characterization of ice particles and abundance of supercooled droplets.

scholarly journals Effect of vehicular traffic, remote sources and new particle formation on the activation properties of cloud condensation nuclei in the megacity of São Paulo, Brazil

2016 ◽  
Vol 16 (22) ◽  
pp. 14635-14656 ◽  
Author(s):  
Carlos Eduardo Souto-Oliveira ◽  
Maria de Fátima Andrade ◽  
Prashant Kumar ◽  
Fábio Juliano da Silva Lopes ◽  
Marly Babinski ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Activation Parameters ◽  
Particle Formation ◽  
Sea Salt ◽  
Vehicular Emissions ◽  
Vehicular Traffic ◽  
Condensation Nuclei ◽  
The Impact

Abstract. Atmospheric aerosol is the primary source of cloud condensation nuclei (CCN). The microphysics and chemical composition of aerosols can affect cloud development and the precipitation process. Among studies conducted in Latin America, only a handful have reported the impact of urban aerosol on CCN activation parameters such as activation ratio (AR) and activation diameter (Dact). With over 20 million inhabitants, the Metropolitan Area of São Paulo (MASP) is the largest megacity in South America. To our knowledge, this is the first study to assess the impact that remote sources and new particle formation (NPF) events have on CCN activation properties in a South American megacity. The measurements were conducted in the MASP between August and September 2014. We measured the CCN within the 0.2–1.0 % range of supersaturation, together with particle number concentration (PNC) and particle number distribution (PND), as well as trace-element concentrations and black carbon (BC). NPF events were identified on 35 % of the sampling days. Combining multivariate analysis in the form of positive matrix factorization (PMF) with an aerosol profile from lidar and HYSPLIT model analyses allowed us to identify the main contribution of vehicular traffic on all days and sea salt and biomass burning from remote regions on 28 and 21 % of the sampling days, respectively. The AR and Dact parameters showed distinct patterns for daytime with intense vehicular traffic and nighttime periods. For example, CCN activation was lower during the daytime than during the nighttime periods, a pattern that was found to be associated mainly with local road-traffic emissions. A decrease in CCN activation was observed on the NPF event days, mainly due to high concentrations of particles with smaller diameters. We also found that aerosols from sea salt, industrial emissions, and biomass burning had minor effects on Dact. For example, nights with biomass burning and vehicular emissions showed slightly lower CCN activation properties than sea-salt, industrial and non-event nights. Our results show that particulate matter from local vehicular emissions during the daytime has a greater effect on CCN activation parameters than that from remote sources.

scholarly journals Properties of cloud condensation nuclei (CCN) in the trade wind marine boundary layer of the western North Atlantic

2016 ◽  
Vol 16 (4) ◽  
pp. 2675-2688 ◽  
Author(s):  
Thomas B. Kristensen ◽  
Thomas Müller ◽  
Konrad Kandler ◽  
Nathalie Benker ◽  
Markus Hartmann ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Long Range ◽  
North Atlantic ◽  
Particle Number ◽  
Marine Boundary Layer ◽  
Mineral Dust ◽  
Cloud Condensation Nuclei ◽  
Sea Salt ◽  
Condensation Nuclei ◽  
Accumulation Mode

Abstract. Cloud optical properties in the trade winds over the eastern Caribbean Sea have been shown to be sensitive to cloud condensation nuclei (CCN) concentrations. The objective of the current study was to investigate the CCN properties in the marine boundary layer (MBL) in the tropical western North Atlantic, in order to assess the respective roles of inorganic sulfate, organic species, long-range transported mineral dust and sea-salt particles. Measurements were carried out in June–July 2013, on the east coast of Barbados, and included CCN number concentrations, particle number size distributions and offline analysis of sampled particulate matter (PM) and sampled accumulation mode particles for an investigation of composition and mixing state with transmission electron microscopy (TEM) in combination with energy-dispersive X-ray spectroscopy (EDX). During most of the campaign, significant mass concentrations of long-range transported mineral dust was present in the PM, and influence from local island sources can be ruled out. The CCN and particle number concentrations were similar to what can be expected in pristine marine environments. The hygroscopicity parameter κ was inferred, and values in the range 0.2–0.5 were found during most of the campaign, with similar values for the Aitken and the accumulation mode. The accumulation mode particles studied with TEM were dominated by non-refractory material, and concentrations of mineral dust, sea salt and soot were too small to influence the CCN properties. It is highly likely that the CCN were dominated by a mixture of sulfate species and organic compounds.

scholarly journals The impact of the 1783–1784 AD Laki eruption on global aerosol formation processes and cloud condensation nuclei

2010 ◽  
Vol 10 (13) ◽  
pp. 6025-6041 ◽  
Author(s):  
A. Schmidt ◽  
K. S. Carslaw ◽  
G. W. Mann ◽  
M. Wilson ◽  
T. J. Breider ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Northern Hemisphere ◽  
General Circulation ◽  
Cloud Condensation Nuclei ◽  
General Circulation Models ◽  
Aerosol Formation ◽  
Condensation Nuclei ◽  
Upper Troposphere ◽  
Microphysical Processes ◽  
The Impact

Abstract. The 1783–1784 AD Laki flood lava eruption commenced on 8 June 1783 and released 122 Tg of sulphur dioxide gas over the course of 8 months into the upper troposphere and lower stratosphere above Iceland. Previous studies have examined the impact of the Laki eruption on sulphate aerosol and climate using general circulation models. Here, we study the impact on aerosol microphysical processes, including the nucleation of new particles and their growth to cloud condensation nuclei (CCN) using a comprehensive Global Model of Aerosol Processes (GLOMAP). Total particle concentrations in the free troposphere increase by a factor ~16 over large parts of the Northern Hemisphere in the 3 months following the onset of the eruption. Particle concentrations in the boundary layer increase by a factor 2 to 5 in regions as far away as North America, the Middle East and Asia due to long-range transport of nucleated particles. CCN concentrations (at 0.22% supersaturation) increase by a factor 65 in the upper troposphere with maximum changes in 3-month zonal mean concentrations of ~1400 cm−3 at high northern latitudes. 3-month zonal mean CCN concentrations in the boundary layer at the latitude of the eruption increase by up to a factor 26, and averaged over the Northern Hemisphere, the eruption caused a factor 4 increase in CCN concentrations at low-level cloud altitude. The simulations show that the Laki eruption would have completely dominated as a source of CCN in the pre-industrial atmosphere. The model also suggests an impact of the eruption in the Southern Hemisphere, where CCN concentrations are increased by up to a factor 1.4 at 20° S. Our model simulations suggest that the impact of an equivalent wintertime eruption on upper tropospheric CCN concentrations is only about one-third of that of a summertime eruption. The simulations show that the microphysical processes leading to the growth of particles to CCN sizes are fundamentally different after an eruption when compared to the unperturbed atmosphere, underlining the importance of using a fully coupled microphysics model when studying long-lasting, high-latitude eruptions.

scholarly journals Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Julia Schmale ◽  
Silvia Henning ◽  
Bas Henzing ◽  
Helmi Keskinen ◽  
Karine Sellegri ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Radiative Forcing ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Size Distributions ◽  
Atmospheric Conditions ◽  
Condensation Nuclei ◽  
Retrieval Method ◽  
Particle Properties ◽  
Aerosol Cloud Interactions

Abstract Cloud condensation nuclei (CCN) number concentrations alongside with submicrometer particle number size distributions and particle chemical composition have been measured at atmospheric observatories of the Aerosols, Clouds, and Trace gases Research InfraStructure (ACTRIS) as well as other international sites over multiple years. Here, harmonized data records from 11 observatories are summarized, spanning 98,677 instrument hours for CCN data, 157,880 for particle number size distributions, and 70,817 for chemical composition data. The observatories represent nine different environments, e.g., Arctic, Atlantic, Pacific and Mediterranean maritime, boreal forest, or high alpine atmospheric conditions. This is a unique collection of aerosol particle properties most relevant for studying aerosol-cloud interactions which constitute the largest uncertainty in anthropogenic radiative forcing of the climate. The dataset is appropriate for comprehensive aerosol characterization (e.g., closure studies of CCN), model-measurement intercomparison and satellite retrieval method evaluation, among others. Data have been acquired and processed following international recommendations for quality assurance and have undergone multiple stages of quality assessment.

scholarly journals Impact of aerosol-radiation interaction on new particle formation

2021 ◽  
Author(s):  
Gang Zhao ◽  
Yishu Zhu ◽  
Zhijun Wu ◽  
Taomou Zong ◽  
Jingchuan Chen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Cloud Condensation Nuclei ◽  
Particle Formation ◽  
Aerosol Size Distribution ◽  
Transfer Model ◽  
New Particle Formation ◽  
Condensation Nuclei ◽  
The Impact ◽  
Different Altitudes ◽  
Upper Boundary

Abstract. New particle formation (NPF) is thought to contribute to half of the global cloud condensation nuclei. A better understanding of the NPF at different altitudes can help assess the impact of NPF on cloud formation and corresponding physical properties. However, NPF is not sufficiently understood in the upper boundary layer because previous studies mainly focus on ground-level measurements. In this study, the developments of aerosol size distribution at different altitudes are characterized based on the field measurement conducted in January 2019, in Beijing, China. We find that the partition of nucleation mode particles at the upper boundary layer is larger than that at the ground, which implies that the nucleation processing is more likely to happen in the upper boundary layer than that at the ground. Results of the radiative transfer model show that the photolysis rates of the nitrogen dioxide and ozone increase with altitude within the boundary layer, which lead to a higher concentration of sulfuric acid at the upper boundary layer than that at the ground. Therefore, the nucleation processing in the upper boundary layer should be stronger than that at the ground, which is consistent with our measurement results. Our study emphasizes the influence of aerosol-radiation interaction on the NPF. These results have the potential to improve our understanding of source of cloud condensation nuclei in global scale due to the impacts of aerosol-radiation interaction.

New Directions: The impact of oceanic iron fertilisation on cloud condensation nuclei

2008 ◽  
Vol 42 (22) ◽  
pp. 5728-5730 ◽  
Author(s):  
Matthew T. Woodhouse ◽  
Graham W. Mann ◽  
Kenneth S. Carslaw ◽  
Olivier Boucher
Keyword(s):  
Cloud Condensation Nuclei ◽  
Condensation Nuclei ◽  
New Directions ◽  
The Impact

scholarly journals Summertime observations of ultrafine particles and cloud condensation nuclei from the boundary layer to the free troposphere in the Arctic

2016 ◽  
Author(s):  
Julia Burkart ◽  
Megan D. Willis ◽  
Heiko Bozem ◽  
Jennie L. Thomas ◽  
Kathy Law ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Ultrafine Particles ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Open Ocean ◽  
The Arctic ◽  
Condensation Nuclei ◽  
Aerosol Composition ◽  
Low Level ◽  
20 Nm

Abstract. The Arctic is extremely sensitive to climate change. Shrinking sea ice extent increases the area covered by open ocean during Arctic summer, which impacts the surface albedo and aerosol and cloud properties among many things. In this context extensive aerosol measurements (aerosol composition, particle number and size, cloud condensation nuclei, and trace gases) were made during 11 flights of the NETCARE July, 2014 airborne campaign conducted from Resolute Bay, Nunavut (74N, 94W). Flights routinely included vertical profiles from about 60 to 3000 m a.g.l. as well as several low-level horizontal transects over open ocean, fast ice, melt ponds, and polynyas. Here we discuss the vertical distribution of ultrafine particles (UFP, particle diameter, dp: 5–20 nm), size distributions of larger particles (dp: 20 nm to 1 μm), and cloud condensation nuclei (CCN, supersaturation = 0.6 %) in relation to meteorological conditions and underlying surfaces. UFPs were observed predominantly within the boundary layer, where concentrations were often several hundreds to a few thousand particles per cubic centimeter. Occasionally, particle concentrations below 10 cm−3 were found. The highest UFP concentrations were observed above open ocean and at the top of low-level clouds, whereas numbers over ice-covered regions were substantially lower. Overall, UFP formation events were frequent in a clean boundary layer with a low condensation sink. In a few cases this ultrafine mode extended to sizes larger than 40 nm, suggesting that these UFP can grow into a size range where they can impact clouds and therefore climate.

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