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

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.

Download Full-text

Effect of local and remote sources and new particle formation events on the activation properties of cloud condensation nuclei in the Brazilian megacity of São Paulo

10.5194/acp-2016-241 ◽

2016 ◽

Cited By ~ 1

Author(s):

Carlos Eduardo Souto-Oliveira ◽

Maria de Fátima Andrade ◽

Prashant Kumar ◽

Fábio Juliano da Silva Lopes ◽

Marly Babinski ◽

...

Keyword(s):

South America ◽

Biomass Burning ◽

Cloud Condensation Nuclei ◽

Activation Parameters ◽

Sao Paulo ◽

Sea Salt ◽

Traffic Emissions ◽

São Paulo ◽

Condensation Nuclei ◽

The Impact

Abstract. Atmospheric aerosol is the most important source of cloud condensation nuclei (CCN). Microphysics and chemical composition of aerosols can affect cloud development and precipitation process. Only a few studies in Latin American have reported the impact of urban aerosol on CCN activation parameters such as activated ratio (AR) and activation diameter (Dact). Sao Paulo Metropolitan Area (SPMA) is the biggest megacity of South America with over 20 million inhabitants. This is the first study in a megacity on South America to assess the impact of remote sources and new particle formation (NPF) events on CCN activation properties. The measurements were conducted at São Paulo city from August to September 2014. The CCN were measured within the 0.2–1.0 % range of supersaturation, simultaneous with particle number concentration (PNC) and distribution (PND), trace elemental concentrations (TEC) and black carbon (BC). The NPF events were identified during 35 % of the sampling days. Combination of TEC and BC associated with aerosol profile from Lidar analysis and Hysplit trajectories allowed to identify sea-salt and biomass burning contribution from remote regions as 28 % and 21 % of total number of days, respectively. The AR and Dact parameters presented a clearly different pattern for diurnal and nocturnal periods. The diurnal periods presented lower CCN activation than the nocturnal durations and this pattern was found to be associated mainly with local vehicular traffic emissions. NPF events showed a negative feedback to CCN activation. Weak effects of sea-salt and biomass burning aerosols could be observed on activation parameters as sea-salt showed a positive feedback. The results of this study show that particulate matter from local traffic emissions has the main effect on activation parameters compared with remote sources.

Download Full-text

Wintertime new particle formation and its contribution to cloud condensation nuclei in the Northeastern United States

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-2591-2020 ◽

2020 ◽

Vol 20 (4) ◽

pp. 2591-2601

Author(s):

Fangqun Yu ◽

Gan Luo ◽

Arshad Arjunan Nair ◽

James J. Schwab ◽

James P. Sherman ◽

...

Keyword(s):

United States ◽

Particle Number ◽

Hydrological Cycle ◽

Cloud Condensation Nuclei ◽

Particle Formation ◽

New Particle Formation ◽

Northeastern United States ◽

Condensation Nuclei ◽

Upper Troposphere ◽

Inorganic Species

Abstract. Atmospheric particles can act as cloud condensation nuclei (CCN) and modify cloud properties and precipitation and thus indirectly impact the hydrological cycle and climate. New particle formation (NPF or nucleation), frequently observed at locations around the globe, is an important source of ultrafine particles and CCN in the atmosphere. In this study, wintertime NPF over the Northeastern United States (NEUS) is simulated with WRF-Chem coupled with a size-resolved (sectional) advanced particle microphysics (APM) model. Model-simulated variations in particle number concentrations during a 2-month period (November–December 2013) are in agreement with corresponding measurements taken at Pinnacle State Park (PSP), New York, and Appalachian State University (APP), North Carolina. We show that, even during wintertime, regional nucleation occurs and contributes significantly to ultrafine-particle and CCN number concentrations over the NEUS. The model shows that, due to low biogenic emissions during this period, wintertime regional nucleation is solely controlled by inorganic species and the newly developed ternary ion-mediated nucleation scheme is able to capture the variations in observed particle number concentrations (ranging from ∼200 to 20 000 cm−3) at both PSP and APP. Total particle and CCN number concentrations dramatically increase following NPF events and have the highest values over the Ohio Valley region, where elevated [SO2] is sustained by power plants. Secondary particles dominate particle number abundance over the NEUS, and their fraction increases with altitude from ≳85 % near the surface to ≳95 % in the upper troposphere. The secondary fraction of CCN also increases with altitude, from 20 %–50 % in the lower boundary layer to 50 %–60 % in the middle troposphere to 70 %–85 % in the upper troposphere.

Download Full-text

Impact of aerosol–radiation interaction on new particle formation

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-9995-2021 ◽

2021 ◽

Vol 21 (13) ◽

pp. 9995-10004

Author(s):

Gang Zhao ◽

Yishu Zhu ◽

Zhijun Wu ◽

Taomou Zong ◽

Jingchuan Chen ◽

...

Keyword(s):

Cloud Condensation Nuclei ◽

Mixing Layer ◽

Particle Formation ◽

Radiative Transfer Model ◽

Aerosol Size Distribution ◽

Transfer Model ◽

New Particle Formation ◽

Condensation Nuclei ◽

The Impact ◽

Different Altitudes

Abstract. New particle formation (NPF) is thought to contribute 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 mixing layer because previous studies mainly focused 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 in the upper mixing layer is larger than that at the ground, which implies that the nucleation processing is more likely to happen in the upper mixing 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 mixing layer, which leads to a higher concentration of sulfuric acid in the upper mixing layer than that at the ground. Therefore, the nucleation processing in the upper mixing 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 the source of cloud condensation nuclei on a global scale due to the impacts of aerosol–radiation interaction.

Download Full-text

Submicron aerosols at thirteen diversified sites in China: size distribution, new particle formation and corresponding contribution to cloud condensation nuclei production

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-15149-2014 ◽

2014 ◽

Vol 14 (10) ◽

pp. 15149-15189 ◽

Cited By ~ 2

Author(s):

J. F. Peng ◽

M. Hu ◽

Z. B. Wang ◽

X. F. Huang ◽

P. Kumar ◽

...

Keyword(s):

Size Distribution ◽

Particle Number ◽

Cloud Condensation Nuclei ◽

Particle Formation ◽

New Particle Formation ◽

Condensation Nuclei ◽

Accumulation Mode ◽

Nucleation Mode ◽

Secondary Formation ◽

Urban Sites

Abstract. Understanding the particle number size distributions in diversified atmospheric environments is important in order to design mitigation strategies related to submicron particles and their effect on regional air quality, haze and human health. In this study, we conducted 15 different field measurement campaigns, each one-month long, between 2007 and 2011 at 13 individual sites in China. These were 5 urban sites, 4 regional sites, 3 coastal/background sites and one ship cruise measurement along eastern coastline of China. Size resolved particles were measured in the 15–600 nm size range. The median particle number concentrations (PNC) were found to vary in the range of 1.1–2.2 × 104 cm−3 at urban sites, 0.8–1.5 × 104 cm−3 at regional sites, 0.4–0.6 × 104 cm−3 at coastal/background sites, and 0.5 × 104 cm−3 during cruise measurements. Peak diameters at each of these sites varied greatly from 24 nm to 115 nm. Particles in the 15–25 nm (nucleation mode), 25–100 nm (Aitken mode) and 100–600 nm (accumulation mode) range showed different characteristics at each of the studied sites, indicating the features of primary emissions and secondary formation in these diversified atmospheric environments. Diurnal variations show a build-up of accumulation mode particles belt at regional sites, suggesting the contribution of regional secondary aerosol pollution. Frequencies of new particle formation (NPF) events were much higher at urban and regional sites than at coastal sites and cruise measurement. The average growth rates (GRs) of nucleation mode particles were 8.0–10.9 nm h−1 at urban sites, 7.4–13.6 nm h−1 at regional sites and 2.8–7.5 nm h−1 at both coastal and cruise measurement sites. The high gaseous precursors and strong oxidation at urban and regional sites not only favored the formation of particles, but also accelerated the growth rate of the nucleation mode particles. No significant difference in condensation sink (CS) during NPF days were observed among different site types, suggesting that the NPF events in background area were more influenced by the pollutant transport. In addition, average contributions of NPF events to potential cloud condensation nuclei (CCN) at 0.2% super-saturation in the afternoon of all sampling days were calculated as 11% and 6% at urban sites and regional sites, respectively. On the other hand, NPF events at coastal and cruise measurement sites had little impact on potential production of CCN. This study provides a large dataset of aerosol size distribution in diversified atmosphere of China, improving our general understanding of emission, secondary formation, new particles formation and corresponding CCN activity of submicron aerosols in Chinese environments.

Download Full-text

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-1949-2011 ◽

2011 ◽

Vol 11 (5) ◽

pp. 1949-1959 ◽

Cited By ~ 36

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).

Download Full-text

New particle formation and growth in biomass burning plumes: An important source of cloud condensation nuclei

Geophysical Research Letters ◽

10.1029/2012gl050930 ◽

2012 ◽

Vol 39 (9) ◽

pp. n/a-n/a ◽

Cited By ~ 43

Author(s):

Christopher J. Hennigan ◽

Daniel M. Westervelt ◽

Ilona Riipinen ◽

Gabriella J. Engelhart ◽

Taehyoung Lee ◽

...

Keyword(s):

Biomass Burning ◽

Cloud Condensation Nuclei ◽

Particle Formation ◽

New Particle Formation ◽

Condensation Nuclei ◽

Particle Formation And Growth

Download Full-text

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-2675-2016 ◽

2016 ◽

Vol 16 (4) ◽

pp. 2675-2688 ◽

Cited By ~ 21

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.

Download Full-text

Regional new particle formation as modulators of cloud condensation nuclei and cloud droplet number in the eastern Mediterranean

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-6185-2019 ◽

2019 ◽

Vol 19 (9) ◽

pp. 6185-6203 ◽

Cited By ~ 8

Author(s):

Panayiotis Kalkavouras ◽

Aikaterini Bougiatioti ◽

Nikos Kalivitis ◽

Iasonas Stavroulas ◽

Maria Tombrou ◽

...

Keyword(s):

Eastern Mediterranean ◽

Cloud Condensation Nuclei ◽

Cloud Droplet ◽

Particle Formation ◽

Cloud Formation ◽

New Particle Formation ◽

Condensation Nuclei ◽

Low Cloud ◽

Condensational Growth ◽

The Impact

Abstract. A significant fraction of atmospheric particles that serve as cloud condensation nuclei (CCN) are thought to originate from the condensational growth of new particle formation (NPF) from the gas phase. Here, 7 years of continuous aerosol and meteorological measurements (June 2008 to May 2015) at a remote background site of the eastern Mediterranean were recorded and analyzed to assess the impact of NPF (of 162 episodes identified) on CCN and cloud droplet number concentration (CDNC) formation in the region. A new metric is introduced to quantitatively determine the initiation and duration of the influence of NPF on the CCN spectrum. NPF days were found to increase CCN concentrations (from 0.10 % to 1.00 % supersaturation) between 29 % and 77 %. Enhanced CCN concentrations from NPF are mostly observed, as expected, under low preexisting particle concentrations and occur in the afternoon, relatively later in the winter and autumn than in the summer. Potential impacts of NPF on cloud formation were quantified by introducing the observed aerosol size distributions and chemical composition into an established cloud droplet parameterization. We find that the supersaturations that develop are very low (ranging between 0.03 % and 0.27 %) for typical boundary layer dynamics (σw ∼0.3 m s−1) and NPF is found to enhance CDNC by a modest 13 %. This considerable contrast between CCN and CDNC response is in part from the different supersaturation levels considered, but also because supersaturation drops from increasing CCN because of water vapor competition effects during the process of droplet formation. The low cloud supersaturation further delays the appearance of NPF impacts on CDNC to clouds formed in the late evening and nighttime – which has important implications for the extent and types of indirect effects induced by NPF events. An analysis based on CCN concentrations using prescribed supersaturation can provide very different, even misleading, conclusions and should therefore be avoided. The proposed approach here offers a simple, yet highly effective way for a more realistic impact assessment of NPF events on cloud formation.

Download Full-text

Description and evaluation of GLOMAP-mode: a modal global aerosol microphysics model for the UKCA composition-climate model

Geoscientific Model Development ◽

10.5194/gmd-3-519-2010 ◽

2010 ◽

Vol 3 (2) ◽

pp. 519-551 ◽

Cited By ~ 267

Author(s):

G. W. Mann ◽

K. S. Carslaw ◽

D. V. Spracklen ◽

D. A. Ridley ◽

P. T. Manktelow ◽

...

Keyword(s):

Climate Model ◽

Cloud Condensation Nuclei ◽

Particle Growth ◽

Particle Formation ◽

Sea Salt ◽

Condensation Nuclei ◽

Aerosol Dynamics ◽

Cloud Processing ◽

Cloud Scavenging ◽

Primary Emissions

Abstract. A new version of the Global Model of Aerosol Processes (GLOMAP) is described, which uses a two-moment pseudo-modal aerosol dynamics approach rather than the original two-moment bin scheme. GLOMAP-mode simulates the multi-component global aerosol, resolving sulfate, sea-salt, dust, black carbon (BC) and particulate organic matter (POM), the latter including primary and biogenic secondary POM. Aerosol processes are simulated in a size-resolved manner including primary emissions, secondary particle formation by binary homogeneous nucleation of sulfuric acid and water, particle growth by coagulation, condensation and cloud-processing and removal by dry deposition, in-cloud and below-cloud scavenging. A series of benchmark observational datasets are assembled against which the skill of the model is assessed in terms of normalised mean bias (b) and correlation coefficient (R). Overall, the model performs well against the datasets in simulating concentrations of aerosol precursor gases, chemically speciated particle mass, condensation nuclei (CN) and cloud condensation nuclei (CCN). Surface sulfate, sea-salt and dust mass concentrations are all captured well, while BC and POM are biased low (but correlate well). Surface CN concentrations compare reasonably well in free troposphere and marine sites, but are underestimated at continental and coastal sites related to underestimation of either primary particle emissions or new particle formation. The model compares well against a compilation of CCN observations covering a range of environments and against vertical profiles of size-resolved particle concentrations over Europe. The simulated global burden, lifetime and wet removal of each of the simulated aerosol components is also examined and each lies close to multi-model medians from the AEROCOM model intercomparison exercise.

Download Full-text

Simulation of particle size distribution with a global aerosol model: contribution of nucleation to aerosol and CCN number concentrations

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-10597-2009 ◽

2009 ◽

Vol 9 (2) ◽

pp. 10597-10645 ◽

Cited By ~ 2

Author(s):

F. Yu ◽

G. Luo

Keyword(s):

Particle Number ◽

Transport Model ◽

Cloud Condensation Nuclei ◽

Formation Rate ◽

Sea Salt ◽

Condensation Nuclei ◽

Gaseous Species ◽

Acid Vapor ◽

Aerosol Model ◽

Secondary Particles

Abstract. An advanced particle microphysics model with a number of computationally efficient schemes has been incorporated into a global chemistry transport model (GEOS-Chem) to simulate particle number size distributions and cloud condensation nuclei (CCN) concentrations in the atmosphere. Size-resolved microphysics for secondary particles (i.e., those formed from gaseous species) and sea salt has been treated in the present study. The growth of nucleated particles through the condensation of sulfuric acid vapor and equilibrium uptake of nitrate, ammonium, and secondary organic aerosol is explicitly simulated, along with the scavenging of secondary particles by primary particles (dust, black carbon, organic carbon, and sea salt). We calculate secondary particle formation rate based on ion-mediated nucleation (IMN) mechanism and constrain the parameterizations of primary particle emissions with various observations. Our simulations indicate that secondary particles formed via IMN appear to be able to account for the particle number concentrations observed in many parts of troposphere. A comparison of the simulated annual mean concentrations of condensation nuclei larger than 10 nm (CN10) with those measured values show very good agreement (within a factor of two) in near all 22 sites around the globe that have at least one full year of CN10 measurements. Secondary particles appear to dominate the number abundance in most parts of the troposphere. Calculated CCN concentration at supersaturation of 0.4% (CCN0.4) and the fraction of CCN0.4 that is secondary (fCCNsec) have large spatial variations. Over the middle latitude in the Northern Hemisphere, zonally averaged CCN0.4 decreases from ~400–700 cm−3 in the boundary layer (BL) to below 100 cm−3 above altitude of ~4 km, the corresponding fCCNsec values change from 50–60% to above ~70%. In the Southern Hemisphere, the zonally averaged CCN0.4 is below 200 cm−3 and fCCNsec is generally above 60% except in the BL over the Southern Ocean.

Download Full-text