Articles | Volume 16, issue 22
24 Nov 2016
Research article | 24 Nov 2016
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
Carlos Eduardo Souto-Oliveira et al.
No articles found.
Goran Gašparac, Amela Jeričević, Prashant Kumar, and Branko Grisogono
Atmos. Chem. Phys., 20, 6395–6415,Short summary
Two different available air quality modelling systems were used to investigate physical and chemical processes that contributed to increased daily background PM10 in all of Europe (focusing on eastern and central Europe). Differentiation of modelling performance in respect to the terrain height was found. A strong influence of meteorological conditions on increased background PM10 and statically stable atmospheric conditions were recognized as a key factor in the build-up of background PM10.
Gregori de Arruda Moreira, Fábio Juliano da Silva Lopes, Juan Luis Guerrero-Rascado, Jonatan João da Silva, Antonio Arleques Gomes, Eduardo Landulfo, and Lucas Alados-Arboledas
Atmos. Meas. Tech., 12, 4261–4276,Short summary
In this paper, we present a comparative analysis of the use of lidar-backscattered signals at three wavelengths (355, 532 and 1064 nm) to study the ABL by investigating high-order moments, which gives us information about the ABL height (derived using the variance method), aerosol layer movements (skewness) and mixing conditions (kurtosis) at several heights.
Mona Kurppa, Antti Hellsten, Pontus Roldin, Harri Kokkola, Juha Tonttila, Mikko Auvinen, Christoph Kent, Prashant Kumar, Björn Maronga, and Leena Järvi
Geosci. Model Dev., 12, 1403–1422,Short summary
This paper describes the implementation of a sectional aerosol module, SALSA, into the PALM model system 6.0. The first evaluation study shows excellent agreements with measurements. Furthermore, we show that ignoring the dry deposition of aerosol particles can overestimate aerosol number concentrations by 20 %, whereas condensation and dissolutional growth increase the total aerosol mass by over 10 % in this specific urban environment.
Gregori de Arruda Moreira, Juan Luis Guerrero-Rascado, Jose A. Benavent-Oltra, Pablo Ortiz-Amezcua, Roberto Román, Andrés E. Bedoya-Velásquez, Juan Antonio Bravo-Aranda, Francisco Jose Olmo Reyes, Eduardo Landulfo, and Lucas Alados-Arboledas
Atmos. Chem. Phys., 19, 1263–1280,Short summary
In this study we show the capabilities of combining different remote sensing systems (microwave radiometer – MWR, Doppler lidar – DL – and elastic lidar – EL) for retrieving a detailed picture of the PBL turbulent features. Concerning EL, in addition to analyzing the influence of noise, we explore the use of different wavelengths, which usually includes EL systems operated in extended networks, like EARLINET, LALINET, MPLNET or SKYNET.
Igor Veselovskii, Philippe Goloub, Qiaoyun Hu, Thierry Podvin, David N. Whiteman, Mikhael Korenskiy, and Eduardo Landulfo
Atmos. Meas. Tech., 12, 119–128,Short summary
Methane is currently the second most important greenhouse gas of anthropogenic origin (after carbon dioxide) and its concentration can be increased inside the boundary layer. So, the development of instruments for vertical profiling of the methane mixing ratio is an important task. We present the results of methane profiling in the lower troposphere using LILAS Raman lidar from the Lille University observatory platform (France).
Guilherme Martins Pereira, Kimmo Teinilä, Danilo Custódio, Aldenor Gomes Santos, Huang Xian, Risto Hillamo, Célia A. Alves, Jailson Bittencourt de Andrade, Gisele Olímpio da Rocha, Prashant Kumar, Rajasekhar Balasubramanian, Maria de Fátima Andrade, and Pérola de Castro Vasconcellos
Atmos. Chem. Phys., 17, 11943–11969,Short summary
São Paulo, Brazil, has relatively relaxed regulations for ambient air pollution standards and often presents high air pollution levels due to emissions of airborne particles from local sources and long-range transport of biomass burning smoke. High risks associated with particulate matter exposure were observed in most samples. The results highlighted the contribution of vehicular emissions and the significant input from biomass combustion in the dry season.
A Vara-Vela, M. F. Andrade, P. Kumar, R. Y. Ynoue, and A. G. Muñoz
Atmos. Chem. Phys., 16, 777–797,Short summary
This study provides a first step to understand the impact of vehicular emissions on the formation of secondary particles as well as the feedback between these particles and meteorology in the Sao Paulo Metropolitan Area (SPMA). Among the main research findings are: - The emissions of primary gases from vehicles led to a production between 20 and 30 % due to new particles formation in relation to the total mass concentration PM2.5 in the downtown SPMA.
J. F. Peng, M. Hu, Z. B. Wang, X. F. Huang, P. Kumar, Z. J. Wu, S. Guo, D. L. Yue, D. J. Shang, Z. Zheng, and L. Y. He
Atmos. Chem. Phys., 14, 10249–10265,
J. Brito, L. V. Rizzo, P. Herckes, P. C. Vasconcellos, S. E. S. Caumo, A. Fornaro, R. Y. Ynoue, P. Artaxo, and M. F. Andrade
Atmos. Chem. Phys., 13, 12199–12213,
F. J. S. Lopes, E. Landulfo, and M. A. Vaughan
Atmos. Meas. Tech., 6, 3281–3299,
E. G. Larroza, W. M. Nakaema, R. Bourayou, C. Hoareau, E. Landulfo, and P. Keckhut
Atmos. Meas. Tech., 6, 3197–3210,
Related subject area
Subject: Clouds and Precipitation | Research Activity: Field Measurements | Altitude Range: Troposphere | Science Focus: Physics (physical properties and processes)In situ microphysics observations of intense pyroconvection from a large wildfireConditions favorable for secondary ice production in Arctic mixed-phase cloudsInteraction between cloud–radiation, atmospheric dynamics and thermodynamics based on observational data from GoAmazon 2014/15 and a cloud-resolving modelSnowfall in Northern Finland derives mostly from ice cloudsObservation of secondary ice production in clouds at low temperaturesIn situ and satellite-based estimates of cloud properties and aerosol–cloud interactions over the southeast Atlantic OceanIce fog observed at cirrus temperatures at Dome C, Antarctic PlateauLife cycle of stratocumulus clouds over 1 year at the coast of the Atacama DesertUpper tropospheric slightly ice-subsaturated regions: Frequency of occurrence and statistical evidence for the appearance of contrail cirrusExperimental study on the evolution of droplet size distribution during the fog life cycleSignificant continental source of ice-nucleating particles at the tip of Chile's southernmost Patagonia regionRetrieving ice-nucleating particle concentration and ice multiplication factors using active remote sensing validated by in situ observationsExamination of Aerosol Indirect Effects during Cirrus Cloud EvolutionTemporal and vertical distributions of the occurrence of cirrus clouds over a coastal station in the Indian monsoon regionContinental thunderstorm ground enhancement observed at an exceptionally low altitudeIce-nucleating particles from multiple aerosol sources in the urban environment of Beijing under mixed-phase cloud conditionsIn situ observation of riming in mixed-phase clouds using the PHIPS probeMeasurement report: Introduction to the HyICE-2018 campaign for measurements of ice-nucleating particles and instrument inter-comparison in the Hyytiälä boreal forestNorth Atlantic Ocean SST-gradient-driven variations in aerosol and cloud evolution along Lagrangian cold-air outbreak trajectoriesFactors affecting precipitation formation and precipitation susceptibility of marine stratocumulus with variable above- and below-cloud aerosol concentrations over the Southeast AtlanticAn assessment of macrophysical and microphysical cloud properties driving radiative forcing of shallow trade-wind cloudsHigh concentrations of ice crystals in upper-tropospheric tropical clouds: is there a link to biomass and fossil fuel combustion?Atmospheric rivers and associated precipitation patterns during the ACLOUD and PASCAL campaigns near Svalbard (May–June 2017): case studies using observations, reanalyses, and a regional climate modelMass of different snow crystal shapes derived from fall speed measurementsMeasurement report: Impact of African aerosol particles on cloud evolution in a tropical montane cloud forest in the CaribbeanAnnual exposure to polycyclic aromatic hydrocarbons in urban environments linked to wintertime wood-burning episodesReduced ice number concentrations in contrails from low-aromatic biofuel blendsDistinct impacts on precipitation by aerosol radiative effect over three different megacity regions of eastern ChinaEstimation of the terms acting on local 1 h surface temperature variations in Paris region: the specific contribution of cloudsContrasting characteristics of open- and closed-cellular stratocumulus cloud in the eastern North AtlanticMass and density of individual frozen hydrometeorsLinear relationship between effective radius and precipitation water content near the top of convective clouds: measurement results from ACRIDICON–CHUVA campaignSupercooled liquid water and secondary ice production in Kelvin–Helmholtz instability as revealed by radar Doppler spectra observationsMorning boundary layer conditions for shallow to deep convective cloud evolution during the dry season in the central AmazonAnalysis of aerosol–cloud interactions and their implications for precipitation formation using aircraft observations over the United Arab EmiratesImpact of wind pattern and complex topography on snow microphysics during International Collaborative Experiment for PyeongChang 2018 Olympic and Paralympic winter games (ICE-POP 2018)Evaluation of simulated cloud liquid water in low clouds over the Beaufort Sea in the Arctic System Reanalysis using ARISE airborne in situ observationsComprehensive quantification of height dependence of entrainment mixing between stratiform cloud top and environmentSunlight-absorbing aerosol amplifies the seasonal cycle in low-cloud fraction over the southeast AtlanticCoupled and decoupled stratocumulus-topped boundary layers: turbulence propertiesShape dependence of snow crystal fall speedCaptured cirrus ice particles in high definitionWhat drives daily precipitation over the central Amazon? Differences observed between wet and dry seasonsMicrophysical investigation of the seeder and feeder region of an Alpine mixed-phase cloudCase study of a humidity layer above Arctic stratocumulus and potential turbulent coupling with the cloud topJoint cloud water path and rainwater path retrievals from airborne ORACLES observationsLagrangian matches between observations from aircraft, lidar and radar in a warm conveyor belt crossing orographyInfluence of low-level blocking and turbulence on the microphysics of a mixed-phase cloud in an inner-Alpine valleyObserved trends in clouds and precipitation (1983–2009): implications for their cause(s)Statistical characteristics of raindrop size distribution over the Western Ghats of India: wet versus dry spells of the Indian summer monsoon
David E. Kingsmill, Jeffrey R. French, and Neil P. Lareau
Atmos. Chem. Phys., 23, 1–21,Short summary
This study uses in situ aircraft measurements to characterize the size and shape distributions of 10 µm to 6 mm diameter particles observed during six penetrations of wildfire-induced pyroconvection. Particles sampled in one penetration of a smoke plume are most likely pyrometeors composed of ash. The other penetrations are through pyrocumulus clouds where particle composition is most likely a combination of hydrometeors (ice particles) and pyrometeors (ash).
Julie Thérèse Pasquier, Jan Henneberger, Fabiola Ramelli, Annika Lauber, Robert Oscar David, Jörg Wieder, Tim Carlsen, Rosa Gierens, Marion Maturilli, and Ulrike Lohmann
Atmos. Chem. Phys., 22, 15579–15601,Short summary
It is important to understand how ice crystals and cloud droplets form in clouds, as their concentrations and sizes determine the exact radiative properties of the clouds. Normally, ice crystals form from aerosols, but we found evidence for the formation of additional ice crystals from the original ones over a large temperature range within Arctic clouds. In particular, additional ice crystals were formed during collisions of several ice crystals or during the freezing of large cloud droplets.
Layrson J. M. Gonçalves, Simone M. S. C. Coelho, Paulo Y. Kubota, and Dayana C. Souza
Atmos. Chem. Phys., 22, 15509–15526,Short summary
This research aims to study the environmental conditions that are favorable and not favorable to cloud formation, in this case specifically for the Amazon region. The results found in this research will be used to improve the representation of clouds in numerical models that are used in weather and climate prediction. In general, it is expected that with better knowledge regarding the cloud–radiation interaction, it is possible to make a better forecast of weather and climate.
Claudia Mignani, Lukas Zimmermann, Rigel Kivi, Alexis Berne, and Franz Conen
Atmos. Chem. Phys., 22, 13551–13568,Short summary
We determined over the course of 8 winter months the phase of clouds associated with snowfall in Northern Finland using radiosondes and observations of ice particle habits at ground level. We found that precipitating clouds were extending from near ground to at least 2.7 km altitude and approximately three-quarters of them were likely glaciated. Possible moisture sources and ice formation processes are discussed.
Alexei Korolev, Paul J. DeMott, Ivan Heckman, Mengistu Wolde, Earle Williams, David J. Smalley, and Michael F. Donovan
Atmos. Chem. Phys., 22, 13103–13113,Short summary
The present study provides the first explicit in situ observation of secondary ice production at temperatures as low as −27 °C, which is well outside the range of the Hallett–Mossop process (−3 to −8 °C). This observation expands our knowledge of the temperature range of initiation of secondary ice in clouds. The obtained results are intended to stimulate laboratory and theoretical studies to develop physically based parameterizations for weather prediction and climate models.
Siddhant Gupta, Greg M. McFarquhar, Joseph R. O'Brien, Michael R. Poellot, David J. Delene, Ian Chang, Lan Gao, Feng Xu, and Jens Redemann
Atmos. Chem. Phys., 22, 12923–12943,Short summary
The ability of NASA’s Terra and Aqua satellites to retrieve cloud properties and estimate the changes in cloud properties due to aerosol–cloud interactions (ACI) was examined. There was good agreement between satellite retrievals and in situ measurements over the southeast Atlantic Ocean. This suggests that, combined with information on aerosol properties, satellite retrievals of cloud properties can be used to study ACI over larger domains and longer timescales in the absence of in situ data.
Étienne Vignon, Lea Raillard, Christophe Genthon, Massimo Del Guasta, Andrew J. Heymsfield, Jean-Baptiste Madeleine, and Alexis Berne
Atmos. Chem. Phys., 22, 12857–12872,Short summary
The near-surface atmosphere over the Antarctic Plateau is cold and pristine and resembles to a certain extent the high troposphere where cirrus clouds form. In this study, we use innovative humidity measurements at Concordia Station to study the formation of ice fogs at temperatures <−40°C. We provide observational evidence that ice fogs can form through the homogeneous freezing of solution aerosols, a common nucleation pathway for cirrus clouds.
Jan H. Schween, Camilo del Rio, Juan-Luis García, Pablo Osses, Sarah Westbrook, and Ulrich Löhnert
Atmos. Chem. Phys., 22, 12241–12267,Short summary
Marine stratocumulus clouds of the eastern Pacific play an essential role in the Earth's climate. These clouds form the major source of water to parts of the extreme dry Atacama Desert at the northern coast of Chile. For the first time these clouds are observed over a whole year with three remote sensing instruments. It is shown how these clouds are influenced by the land–sea wind system and the distribution of ocean temperatures.
Yun Li, Christoph Mahnke, Susanne Rohs, Ulrich Bundke, Nicole Spelten, Georgios Dekoutsidis, Silke Groß, Christiane Voigt, Ulrich Schumann, Andreas Petzold, and Martina Krämer
Atmos. Chem. Phys. Discuss.,
Preprint under review for ACPShort summary
The radiative effect of aviation-induced cirrus is closely related to ambient conditions and their microphysical properties. Our study investigated the occurrence of contrail and natural cirrus measured above Central Europe in 2014. It finds that contrail cirrus appears frequently in the pressure range 200 to 245 hPa and occurs more often in slightly ice-subsaturated environments than expected. The avoidance of slightly ice-subsaturated regions by aviation might thus mitigate contrail cirrus.
Marie Mazoyer, Frédéric Burnet, and Cyrielle Denjean
Atmos. Chem. Phys., 22, 11305–11321,Short summary
The evolution of the droplet size distribution during the fog life cycle remains poorly understood and progress is required to reduce the uncertainty of fog forecasts. To gain insights into the physical processes driving the microphysics, intensive field campaigns were conducted during three winters at the SIRTA site in the south of Paris. This study analyzed the variations in fog microphysical properties and their potential interactions at the different evolutionary stages of the fog events.
Xianda Gong, Martin Radenz, Heike Wex, Patric Seifert, Farnoush Ataei, Silvia Henning, Holger Baars, Boris Barja, Albert Ansmann, and Frank Stratmann
Atmos. Chem. Phys., 22, 10505–10525,Short summary
The sources of ice-nucleating particles (INPs) are poorly understood in the Southern Hemisphere (SH). We studied INPs in the boundary layer in the southern Patagonia region. No seasonal cycle of INP concentrations was observed. The majority of INPs are biogenic particles, likely from local continental sources. The INP concentrations are higher when strong precipitation occurs. While previous studies focused on marine INP sources in SH, we point out the importance of continental sources of INPs.
Jörg Wieder, Nikola Ihn, Claudia Mignani, Moritz Haarig, Johannes Bühl, Patric Seifert, Ronny Engelmann, Fabiola Ramelli, Zamin A. Kanji, Ulrike Lohmann, and Jan Henneberger
Atmos. Chem. Phys., 22, 9767–9797,Short summary
Ice formation and its evolution in mixed-phase clouds are still uncertain. We evaluate the lidar retrieval of ice-nucleating particle concentration in dust-dominated and continental air masses over the Swiss Alps with in situ observations. A calibration factor to improve the retrieval from continental air masses is proposed. Ice multiplication factors are obtained with a new method utilizing remote sensing. Our results indicate that secondary ice production occurs at temperatures down to −30 °C.
Flor Vanessa Maciel, Minghui Diao, and Ryan Patnaude
Atmos. Chem. Phys. Discuss.,
Revised manuscript accepted for ACPShort summary
Aerosol indirect effects on cirrus clouds are investigated during cirrus evolution, using global-scale in-situ observations and climate model simulations. As cirrus evolves, the mechanisms to form ice crystals also change with time. Both small and large aerosols are found to affect cirrus properties. Southern Hemisphere cirrus appears to be more sensitive to additional aerosols. The climate model underestimates ice crystal growth, likely due to biases of relative humidity and vertical velocity.
Saleem Ali, Sanjay Kumar Mehta, Aravindhavel Ananthavel, and Tondapu Venkata Ramesh Reddy
Atmos. Chem. Phys., 22, 8321–8342,Short summary
Multiple cirrus clouds frequently occur over regions of deep convection in the tropics. Tropical convection has a strong diurnal pattern, with peaks in the afternoon to early evening, over the continents. Continuous micropulse lidar observations over a coastal station in the Indian monsoon region enable us, for the first time, to demonstrate a robust diurnal pattern of single and multiple cirrus occurrences, with peaks during the late afternoon and early morning hours, respectively.
Ivana Kolmašová, Ondřej Santolík, Jakub Šlegl, Jana Popová, Zbyněk Sokol, Petr Zacharov, Ondřej Ploc, Gerhard Diendorfer, Ronald Langer, Radek Lán, and Igor Strhárský
Atmos. Chem. Phys., 22, 7959–7973,Short summary
Gamma ray radiation related to thunderstorms was previously observed at the high-altitude mountain observatories or on the western coast of Japan, usually being terminated by lightning discharges. We show unusual observations of gamma rays at an altitude below 1000 m, coinciding with peculiar rapid variations in the vertical electric field, which are linked to inverted intracloud lightning discharges. This indicates that a strong, lower positive-charge region was present inside the thundercloud.
Cuiqi Zhang, Zhijun Wu, Jingchuan Chen, Jie Chen, Lizi Tang, Wenfei Zhu, Xiangyu Pei, Shiyi Chen, Ping Tian, Song Guo, Limin Zeng, Min Hu, and Zamin A. Kanji
Atmos. Chem. Phys., 22, 7539–7556,Short summary
The immersion ice nucleation effectiveness of aerosols from multiple sources in the urban environment remains elusive. In this study, we demonstrate that the immersion ice-nucleating particle (INP) concentration increased dramatically during a dust event in an urban atmosphere. Pollutant aerosols, including inorganic salts formed through secondary transformation (SIA) and black carbon (BC), might not act as effective INPs under mixed-phase cloud conditions.
Fritz Waitz, Martin Schnaiter, Thomas Leisner, and Emma Järvinen
Atmos. Chem. Phys., 22, 7087–7103,Short summary
Riming, i.e., the accretion of small droplets on the surface of ice particles via collision, is one of the major uncertainties in model prediction of mixed-phase clouds. We discuss the occurrence (up to 50% of particles) and aging of rimed ice particles and show correlations of the occurrence and the degree of riming with ambient meteorological parameters using data gathered by the Particle Habit Imaging and Polar Scattering (PHIPS) probe during three airborne in situ field campaigns.
Zoé Brasseur, Dimitri Castarède, Erik S. Thomson, Michael P. Adams, Saskia Drossaart van Dusseldorp, Paavo Heikkilä, Kimmo Korhonen, Janne Lampilahti, Mikhail Paramonov, Julia Schneider, Franziska Vogel, Yusheng Wu, Jonathan P. D. Abbatt, Nina S. Atanasova, Dennis H. Bamford, Barbara Bertozzi, Matthew Boyer, David Brus, Martin I. Daily, Romy Fösig, Ellen Gute, Alexander D. Harrison, Paula Hietala, Kristina Höhler, Zamin A. Kanji, Jorma Keskinen, Larissa Lacher, Markus Lampimäki, Janne Levula, Antti Manninen, Jens Nadolny, Maija Peltola, Grace C. E. Porter, Pyry Poutanen, Ulrike Proske, Tobias Schorr, Nsikanabasi Silas Umo, János Stenszky, Annele Virtanen, Dmitri Moisseev, Markku Kulmala, Benjamin J. Murray, Tuukka Petäjä, Ottmar Möhler, and Jonathan Duplissy
Atmos. Chem. Phys., 22, 5117–5145,Short summary
The present measurement report introduces the ice nucleation campaign organized in Hyytiälä, Finland, in 2018 (HyICE-2018). We provide an overview of the campaign settings, and we describe the measurement infrastructure and operating procedures used. In addition, we use results from ice nucleation instrument inter-comparison to show that the suite of these instruments deployed during the campaign reports consistent results.
Kevin J. Sanchez, Bo Zhang, Hongyu Liu, Matthew D. Brown, Ewan C. Crosbie, Francesca Gallo, Johnathan W. Hair, Chris A. Hostetler, Carolyn E. Jordan, Claire E. Robinson, Amy Jo Scarino, Taylor J. Shingler, Michael A. Shook, Kenneth L. Thornhill, Elizabeth B. Wiggins, Edward L. Winstead, Luke D. Ziemba, Georges Saliba, Savannah L. Lewis, Lynn M. Russell, Patricia K. Quinn, Timothy S. Bates, Jack Porter, Thomas G. Bell, Peter Gaube, Eric S. Saltzman, Michael J. Behrenfeld, and Richard H. Moore
Atmos. Chem. Phys., 22, 2795–2815,Short summary
Atmospheric particle concentrations impact clouds, which strongly impact the amount of sunlight reflected back into space and the overall climate. Measurements of particles over the ocean are rare and expensive to collect, so models are necessary to fill in the gaps by simulating both particle and clouds. However, some measurements are needed to test the accuracy of the models. Here, we measure changes in particles in different weather conditions, which are ideal for comparison with models.
Siddhant Gupta, Greg M. McFarquhar, Joseph R. O'Brien, Michael R. Poellot, David J. Delene, Rose M. Miller, and Jennifer D. Small Griswold
Atmos. Chem. Phys., 22, 2769–2793,Short summary
This study evaluates the impact of biomass burning aerosols on precipitation in marine stratocumulus clouds using observations from the NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) field campaign over the Southeast Atlantic. Instances of contact and separation between aerosol and cloud layers show polluted clouds have a lower precipitation rate and a lower precipitation susceptibility. This information will help improve cloud representation in Earth system models.
Anna E. Luebke, André Ehrlich, Michael Schäfer, Kevin Wolf, and Manfred Wendisch
Atmos. Chem. Phys., 22, 2727–2744,Short summary
A combination of aircraft and satellite observations is used to show how the characteristics of tropical shallow clouds interact with incoming and outgoing energy. A complete depiction of these clouds is challenging to obtain, but such data are useful for understanding how models can correctly represent them. The amount of cloud is found to be the most important factor, while other cloud characteristics become increasingly impactful when more cloud is present.
Graciela B. Raga, Darrel Baumgardner, Blanca Rios, Yanet Díaz-Esteban, Alejandro Jaramillo, Martin Gallagher, Bastien Sauvage, Pawel Wolff, and Gary Lloyd
Atmos. Chem. Phys., 22, 2269–2292,Short summary
The In-Service Aircraft for a Global Observing System (IAGOS) is a small fleet of commercial aircraft that carry a suite of meteorological, gas, aerosol, and cloud sensors and have been measuring worldwide for almost 9 years, since late 2011. Extreme ice events (EIEs) have been identified from the IAGOS cloud measurements and linked to surface emissions for biomass and fossil fuel consumption. The results reported here are highly relevant for climate change and flight operations forecasting.
Carolina Viceto, Irina V. Gorodetskaya, Annette Rinke, Marion Maturilli, Alfredo Rocha, and Susanne Crewell
Atmos. Chem. Phys., 22, 441–463,Short summary
We focus on anomalous moisture transport events known as atmospheric rivers (ARs). During ACLOUD and PASCAL, three AR events were identified: 30 May, 6 June, and 9 June 2017. We explore their spatio-temporal evolution and precipitation patterns using measurements, reanalyses, and a model. We show the importance of the following: Atlantic and Siberian pathways during spring–summer in the Arctic, AR-associated heat/moisture increase, precipitation phase transition, and high-resolution datasets.
Sandra Vázquez-Martín, Thomas Kuhn, and Salomon Eliasson
Atmos. Chem. Phys., 21, 18669–18688,Short summary
High-resolution top- and side-view images of snow ice particles taken by the D-ICI instrument are used to determine the shape; size; cross-sectional area; fall speed; and, based upon these properties, the mass of the individual snow particles. The study analyses the relationships between these fundamental properties as a function of particle shape and highlights that the choice of size parameter, maximum dimension or another characteristic length, is crucial when relating fall speed to mass.
Elvis Torres-Delgado, Darrel Baumgardner, and Olga L. Mayol-Bracero
Atmos. Chem. Phys., 21, 18011–18027,Short summary
African dust aerosols can travel thousands of kilometers and reach the Caribbean and other places, where they can serve as ice and cloud condensation nuclei and alter precipitation patterns. Cloud microphysical properties (droplet number and size) were measured in a Caribbean tropical montane cloud forest along with models and satellite products. The results of the study suggest that meteorology and air mass history are more important for cloud processes than aerosols transported from Africa.
Irini Tsiodra, Georgios Grivas, Kalliopi Tavernaraki, Aikaterini Bougiatioti, Maria Apostolaki, Despina Paraskevopoulou, Alexandra Gogou, Constantine Parinos, Konstantina Oikonomou, Maria Tsagkaraki, Pavlos Zarmpas, Athanasios Nenes, and Nikolaos Mihalopoulos
Atmos. Chem. Phys., 21, 17865–17883,Short summary
We analyze observations from year-long measurements at Athens, Greece. Nighttime wintertime PAH levels are 4 times higher than daytime, and wintertime values are 15 times higher than summertime. Biomass burning aerosol during wintertime pollution events is responsible for these significant wintertime enhancements and accounts for 43 % of the population exposure to PAH carcinogenic risk. Biomass burning poses additional health risks beyond those associated with the high PM levels that develop.
Tiziana Bräuer, Christiane Voigt, Daniel Sauer, Stefan Kaufmann, Valerian Hahn, Monika Scheibe, Hans Schlager, Felix Huber, Patrick Le Clercq, Richard H. Moore, and Bruce E. Anderson
Atmos. Chem. Phys., 21, 16817–16826,Short summary
Over half of aviation climate impact is caused by contrails. Biofuels can reduce the ice crystal numbers in contrails and mitigate the climate impact. The experiment ECLIF II/NDMAX in 2018 assessed the effects of biofuels on contrails and aviation emissions. The NASA DC-8 aircraft performed measurements inside the contrail of the DLR A320. One reference fuel and two blends of the biofuel HEFA and kerosene are analysed. We find a max reduction of contrail ice numbers through biofuel use of 40 %.
Yue Sun and Chuanfeng Zhao
Atmos. Chem. Phys., 21, 16555–16574,Short summary
Using high-resolution multi-year warm season data, the influence of aerosol on precipitation time over the North China Plain (NCP), Yangtze River Delta (YRD), and Pearl River Delta (PRD) is investigated. Aerosol amount and type have significant influence on precipitation time: precipitation start time is advanced by 3 h in the NCP, delayed 2 h in the PRD, and negligibly changed in the YRD. Aerosol impact on precipitation is also influenced by precipitation type and meteorological conditions.
Oscar Javier Rojas Muñoz, Marjolaine Chiriaco, Sophie Bastin, and Justine Ringard
Atmos. Chem. Phys., 21, 15699–15723,Short summary
A method is developed and evaluated to quantify each process that affects hourly 2 m temperature variations on a local scale, based almost exclusively on observations retrieved from an observatory near the Paris region. Each term involved in surface temperature variations is estimated, and its contribution and importance are also assessed. It is found that clouds are the main modulator on hourly temperature variations for most hours of the day, and thus their characterization is addressed.
Michael P. Jensen, Virendra P. Ghate, Dié Wang, Diana K. Apoznanski, Mary J. Bartholomew, Scott E. Giangrande, Karen L. Johnson, and Mandana M. Thieman
Atmos. Chem. Phys., 21, 14557–14571,Short summary
This work compares the large-scale meteorology, cloud, aerosol, precipitation, and thermodynamics of closed- and open-cell cloud organizations using long-term observations from the astern North Atlantic. Open-cell cases are associated with cold-air outbreaks and occur in deeper boundary layers, with stronger winds and higher rain rates compared to closed-cell cases. These results offer important benchmarks for model representation of boundary layer clouds in this climatically important region.
Karlie N. Rees, Dhiraj K. Singh, Eric R. Pardyjak, and Timothy J. Garrett
Atmos. Chem. Phys., 21, 14235–14250,Short summary
Accurate predictions of weather and climate require descriptions of the mass and density of snowflakes as a function of their size. Few measurements have been obtained to date because snowflakes are so small and fragile. This article describes results from a new instrument that automatically measures individual snowflake size, mass, and density. Key findings are that small snowflakes have much lower densities than is often assumed and that snowflake density increases with temperature.
Ramon Campos Braga, Daniel Rosenfeld, Ovid O. Krüger, Barbara Ervens, Bruna A. Holanda, Manfred Wendisch, Trismono Krisna, Ulrich Pöschl, Meinrat O. Andreae, Christiane Voigt, and Mira L. Pöhlker
Atmos. Chem. Phys., 21, 14079–14088,Short summary
Quantifying the precipitation within clouds is crucial for our understanding of the Earth's hydrological cycle. Using in situ measurements of cloud and rain properties over the Amazon Basin and Atlantic Ocean, we show here a linear relationship between the effective radius (re) and precipitation water content near the tops of convective clouds for different pollution states and temperature levels. Our results emphasize the role of re to determine both initiation and amount of precipitation.
Haoran Li, Alexei Korolev, and Dmitri Moisseev
Atmos. Chem. Phys., 21, 13593–13608,Short summary
Kelvin–Helmholtz (K–H) clouds embedded in a stratiform precipitation event were uncovered via radar Doppler spectral analysis. Given the unprecedented detail of the observations, we show that multiple populations of secondary ice columns were generated in the pockets where larger cloud droplets are formed and not at some constant level within the cloud. Our results highlight that the K–H instability is favorable for liquid droplet growth and secondary ice formation.
Alice Henkes, Gilberto Fisch, Luiz A. T. Machado, and Jean-Pierre Chaboureau
Atmos. Chem. Phys., 21, 13207–13225,Short summary
The Amazonian boundary layer is investigated during the dry season in order to better understand the processes that occur between night and day until the stage where shallow cumulus clouds become deep. Observations show that shallow to deep clouds are characterized by a shorter morning transition stage (e.g., the time needed to eliminate the stable boundary layer inversion), while higher humidity above the boundary layer favors the evolution from shallow to deep cumulus clouds.
Youssef Wehbe, Sarah A. Tessendorf, Courtney Weeks, Roelof Bruintjes, Lulin Xue, Roy Rasmussen, Paul Lawson, Sarah Woods, and Marouane Temimi
Atmos. Chem. Phys., 21, 12543–12560,Short summary
The role of dust aerosols as ice-nucleating particles is well established in the literature, whereas their role as cloud condensation nuclei is less understood, particularly in polluted desert environments. We analyze coincident aerosol size distributions and cloud particle imagery collected over the UAE with a research aircraft. Despite the presence of ultra-giant aerosol sizes associated with dust, an active collision–coalescence process is not observed within the limited depths of warm cloud.
Kwonil Kim, Wonbae Bang, Eun-Chul Chang, Francisco J. Tapiador, Chia-Lun Tsai, Eunsil Jung, and Gyuwon Lee
Atmos. Chem. Phys., 21, 11955–11978,Short summary
This study analyzes the microphysical characteristics of snow in complex terrain and the nearby ocean according to topography and wind pattern during the ICE-POP 2018 campaign. The observations from collocated vertically pointing radars and disdrometers indicate that the riming in the mountainous region is likely caused by a strong shear and turbulence. The different behaviors of aggregation and riming were found by three different synoptic patterns (air–sea interaction, cold low, and warm low).
J. Brant Dodson, Patrick C. Taylor, Richard H. Moore, David H. Bromwich, Keith M. Hines, Kenneth L. Thornhill, Chelsea A. Corr, Bruce E. Anderson, Edward L. Winstead, and Joseph R. Bennett
Atmos. Chem. Phys., 21, 11563–11580,Short summary
Aircraft in situ observations of low-level Beaufort Sea cloud properties and thermodynamics from the ARISE campaign are compared with the Arctic System Reanalysis (ASR) to better understand deficiencies in simulated clouds. ASR produces too little cloud water, which coincides with being too warm and dry. In addition, ASR struggles to produce cloud water even in favorable thermodynamic conditions. A random sampling experiment also shows the effects of the limited aircraft sampling on the results.
Sinan Gao, Chunsong Lu, Yangang Liu, Seong Soo Yum, Jiashan Zhu, Lei Zhu, Neel Desai, Yongfeng Ma, and Shang Wu
Atmos. Chem. Phys., 21, 11225–11241,Short summary
Only a few studies have been focused on the vertical variation of entrainment mixing with low resolutions which are crucial to cloud-related processes. A sawtooth pattern allows for an examination of mixing with high vertical resolution. A new measure is introduced to estimate entrainment mixing to overcome difficulties in existing measures, where vertical profile indicates that entrainment mixing becomes more homogeneous with decreasing altitudes, consistent with the dynamical measures.
Jianhao Zhang and Paquita Zuidema
Atmos. Chem. Phys., 21, 11179–11199,Short summary
The subtropical Atlantic hosts one of the planet's largest marine low cloud decks and interacts with biomass burning aerosol from approximately July through October. This study clarifies how the monthly evolution in meteorology and the biomass burning aerosol vertical structure affects the seasonal cycle in its low cloud fraction, such that the July–October evolution in low cloud cover and morphology are reinforced, when compared to scenarios with less aerosol present.
Jakub L. Nowak, Holger Siebert, Kai-Erik Szodry, and Szymon P. Malinowski
Atmos. Chem. Phys., 21, 10965–10991,Short summary
Turbulence properties in two cases of a marine stratocumulus-topped boundary layer have been compared using high-resolution helicopter-borne in situ measurements. In the coupled one, small-scale turbulence was close to isotropic and reasonably followed inertial range scaling according to Kolmogorov theory. In the decoupled one, turbulence was more anisotropic and the scaling deviated from theory. This was more pronounced in the cloud and subcloud layers in comparison to the surface mixed layer.
Sandra Vázquez-Martín, Thomas Kuhn, and Salomon Eliasson
Atmos. Chem. Phys., 21, 7545–7565,Short summary
In this work, we present new fall speed measurements of natural snow particles and ice crystals. We study the particle fall speed relationships and how they depend on particle shape. We analyze these relationships as a function of particle size, cross-sectional area, and area ratio for different particle shape groups. We also investigate the dependence of the particle fall speed on the orientation, as it has a large impact on the cross-sectional area.
Nathan Magee, Katie Boaggio, Samantha Staskiewicz, Aaron Lynn, Xuanyi Zhao, Nicholas Tusay, Terance Schuh, Manisha Bandamede, Lucas Bancroft, David Connelly, Kevin Hurler, Bryan Miner, and Elissa Khoudary
Atmos. Chem. Phys., 21, 7171–7185,Short summary
The cryo-electron microscopy images and analysis in this paper result from the first balloon-borne capture, preservation, and high-resolution imaging of ice particles from cirrus clouds. The images show cirrus particle complexity in unprecedented detail, revealing unexpected morphology, a mixture of surface roughness scales and patterns, embedded aerosols, and a large variety of habits within a single cloud. The results should inform ongoing efforts to refine modeling of cirrus radiative impact.
Thiago S. Biscaro, Luiz A. T. Machado, Scott E. Giangrande, and Michael P. Jensen
Atmos. Chem. Phys., 21, 6735–6754,Short summary
This study suggests that there are two distinct modes driving diurnal precipitating convective clouds over the central Amazon. In the wet season, local factors such as turbulence and nighttime cloud coverage are the main controls of daily precipitation, while dry-season daily precipitation is modulated primarily by the mesoscale convective pattern. The results imply that models and parameterizations must consider different formulations based on the seasonal cycle to correctly resolve convection.
Fabiola Ramelli, Jan Henneberger, Robert O. David, Johannes Bühl, Martin Radenz, Patric Seifert, Jörg Wieder, Annika Lauber, Julie T. Pasquier, Ronny Engelmann, Claudia Mignani, Maxime Hervo, and Ulrike Lohmann
Atmos. Chem. Phys., 21, 6681–6706,Short summary
Orographic mixed-phase clouds are an important source of precipitation, but the ice formation processes within them remain uncertain. Here we investigate the origin of ice crystals in a mixed-phase cloud in the Swiss Alps using aerosol and cloud data from in situ and remote sensing observations. We found that ice formation primarily occurs in cloud top generating cells. Our results indicate that secondary ice processes are active in the feeder region, which can enhance orographic precipitation.
Ulrike Egerer, André Ehrlich, Matthias Gottschalk, Hannes Griesche, Roel A. J. Neggers, Holger Siebert, and Manfred Wendisch
Atmos. Chem. Phys., 21, 6347–6364,Short summary
This paper describes a case study of a three-day period with a persistent humidity inversion above a mixed-phase cloud layer in the Arctic. It is based on measurements with a tethered balloon, complemented with results from a dedicated high-resolution large-eddy simulation. Both methods show that the humidity layer acts to provide moisture to the cloud layer through downward turbulent transport. This supply of additional moisture can contribute to the persistence of Arctic clouds.
Andrew M. Dzambo, Tristan L'Ecuyer, Kenneth Sinclair, Bastiaan van Diedenhoven, Siddhant Gupta, Greg McFarquhar, Joseph R. O'Brien, Brian Cairns, Andrzej P. Wasilewski, and Mikhail Alexandrov
Atmos. Chem. Phys., 21, 5513–5532,Short summary
This work highlights a new algorithm using data collected from the 2016–2018 NASA ORACLES field campaign. This algorithm synthesizes cloud and rain measurements to attain estimates of cloud and precipitation properties over the southeast Atlantic Ocean. Estimates produced by this algorithm compare well against in situ estimates. Increased rain fractions and rain rates are found in regions of atmospheric instability. This dataset can be used to explore aerosol–cloud–precipitation interactions.
Maxi Boettcher, Andreas Schäfler, Michael Sprenger, Harald Sodemann, Stefan Kaufmann, Christiane Voigt, Hans Schlager, Donato Summa, Paolo Di Girolamo, Daniele Nerini, Urs Germann, and Heini Wernli
Atmos. Chem. Phys., 21, 5477–5498,Short summary
Warm conveyor belts (WCBs) are important airstreams in extratropical cyclones, often leading to the formation of intense precipitation. We present a case study that involves aircraft, lidar and radar observations of water and clouds in a WCB ascending from western Europe across the Alps towards the Baltic Sea during the field campaigns HyMeX and T-NAWDEX-Falcon in October 2012. A probabilistic trajectory measure and an airborne tracer experiment were used to confirm the long pathway of the WCB.
Fabiola Ramelli, Jan Henneberger, Robert O. David, Annika Lauber, Julie T. Pasquier, Jörg Wieder, Johannes Bühl, Patric Seifert, Ronny Engelmann, Maxime Hervo, and Ulrike Lohmann
Atmos. Chem. Phys., 21, 5151–5172,Short summary
Interactions between dynamics, microphysics and orography can enhance precipitation. Yet the exact role of these interactions is still uncertain. Here we investigate the role of low-level blocking and turbulence for precipitation by combining remote sensing and in situ observations. The observations show that blocked flow can induce the formation of feeder clouds and that turbulence can enhance hydrometeor growth, demonstrating the importance of local flow effects for orographic precipitation.
Xiang Zhong, Shaw Chen Liu, Run Liu, Xinlu Wang, Jiajia Mo, and Yanzi Li
Atmos. Chem. Phys., 21, 4899–4913,Short summary
The distributions of linear trends in total cloud cover and precipitation in 1983–2009 are both characterized by a broadening of the major ascending zone of Hadley circulation around the Maritime Continent. The broadening is driven primarily by the moisture–convection–latent-heat feedback cycle under global warming conditions. Contribution by other climate oscillations is secondary. The reduction of total cloud cover in China in 1957–2005 is driven by the same mechanism.
Uriya Veerendra Murali Krishna, Subrata Kumar Das, Ezhilarasi Govindaraj Sulochana, Utsav Bhowmik, Sachin Madhukar Deshpande, and Govindan Pandithurai
Atmos. Chem. Phys., 21, 4741–4757,Short summary
Indian summer monsoon (ISM) rainfall exhibits sub-seasonal variability as active spells with good rainfall (wet spell) and weak spells or breaks with little to no rainfall (dry spell). Studies have shown that during the wet and dry periods of the ISM, there are contrasting behaviors in the formation of weather systems and large-scale instability. Thus, it is worth investigating how the raindrop size distribution varies during intra-seasonal timescale variations of the ISM in the Western Ghats.
Almeida, G. P., Brito, J., Morales, C. A., Andrade, M. F., and Artaxo, P.: Measured and modelled cloud condensation nuclei (CCN) concentration in São Paulo, Brazil: the importance of aerosol size-resolved chemical composition on CCN concentration prediction, Atmos. Chem. Phys., 14, 7559–7572, https://doi.org/10.5194/acp-14-7559-2014, 2014.
An, J., Wang, H., Shen, L., Zhu, B., Zou, J., Gao, J., and Kang, H.: Characteristics of new particle formation events in Nanjing, China: Effect of water-soluble ions, Atmos. Environ., 108, 32–40, https://doi.org/10.1016/j.atmosenv.2015.01.038, 2015.
Andrade, M. F., Orsini, C., and Maenhaut, W.: Relation between aerosol sources and meteorological parameters for inhalable atmospheric particles in Sao Paulo City, Brazil, Atmos. Environ., 28, 2307–2315, https://doi.org/10.1016/1352-2310(94)90484-7, 1994.
Andrade, M. F., De Miranda, R. M., Fornaro, A., Kerr, A., Oyama, B., De Andre, P. A., and Saldiva, P.: Vehicle emissions and PM2.5 mass concentrations in six Brazilian cities, Air Qual. Atmos. Health, 5, 79–88, https://doi.org/10.1007/s11869-010-0104-5, 2012.
Andreae, M. O.: The aerosol nucleation puzzle, Science, 339, 911–912, https://doi.org/10.1126/science.1233798, 2013.
Andreae, M. O. and Rosenfeld, D.: Aerosol–cloud–precipitation interactions. Part 1. The nature and sources of cloud-active aerosols, Earth-Sci. Rev., 89, 13–41, https://doi.org/10.1016/j.earscirev.2008.03.001, 2008.
Andreae, M. O., Rosenfeld, D., Artaxo, P., Costa, A. A., Frank, G. P., Longo, K. M., and Silva-Dias, M. A. F.: Smoking rain clouds over the Amazon, Science, 303, 1337–1342, https://doi.org/10.1126/science.1092779, 2004.
Baars, H., Kanitz, T., Engelmann, R., Althausen, D., Heese, B., Komppula, M., Preißler, J., Tesche, M., Ansmann, A., Wandinger, U., Lim, J.-H., Ahn, J. Y., Stachlewska, I. S., Amiridis, V., Marinou, E., Seifert, P., Hofer, J., Skupin, A., Schneider, F., Bohlmann, S., Foth, A., Bley, S., Pfüller, A., Giannakaki, E., Lihavainen, H., Viisanen, Y., Hooda, R. K., Pereira, S. N., Bortoli, D., Wagner, F., Mattis, I., Janicka, L., Markowicz, K. M., Achtert, P., Artaxo, P., Pauliquevis, T., Souza, R. A. F., Sharma, V. P., van Zyl, P. G., Beukes, J. P., Sun, J., Rohwer, E. G., Deng, R., Mamouri, R.-E., and Zamorano, F.: An overview of the first decade of PollyNET: an emerging network of automated Raman-polarization lidars for continuous aerosol profiling, Atmos. Chem. Phys., 16, 5111–5137, https://doi.org/10.5194/acp-16-5111-2016, 2016.
Backman, J., Rizzo, L. V., Hakala, J., Nieminen, T., Manninen, H. E., Morais, F., Aalto, P. P., Siivola, E., Carbone, S., Hillamo, R., Artaxo, P., Virkkula, A., Petäjä, T., and Kulmala, M.: On the diurnal cycle of urban aerosols, black carbon and the occurrence of new particle formation events in springtime São Paulo, Brazil, Atmos. Chem. Phys., 12, 11733–11751, https://doi.org/10.5194/acp-12-11733-2012, 2012.
Betha, R., Spracklen, D. V., and Balasubramanian, R.: Observations of new aerosol particle formation in a tropical urban atmosphere, Atmos. Environ., 71, 340–351, https://doi.org/10.1016/j.atmosenv.2013.01.049, 2013.
Bouéres, L. C. S. and Orsini, C. M. Q.: Fine and coarse elemental components in the urban aerosol of São Paulo, Brazil, Nucl. Instrum. Methods, 181, 417–424, https://doi.org/10.1016/0029-554x(81)90643-1, 1981.
Bougiatioti, A., Nenes, A., Fountoukis, C., Kalivitis, N., Pandis, S. N., and Mihalopoulos, N.: Size-resolved CCN distributions and activation kinetics of aged continental and marine aerosol, Atmos. Chem. Phys., 11, 8791–8808, https://doi.org/10.5194/acp-11-8791-2011, 2011.
Burkart, J., Steiner, G., Reischl, G., and Hitzenberger. R.: Long-term study of cloud condensation nuclei (CCN) activation of the atmospheric aerosol in Vienna, Atmos. Environ., 45, 5751–5759, https://doi.org/10.1016/j.atmosenv.2011.07.022, 2011.
Bzdek, B. R., Pennington, M. R., and Johnston, M. V.: Single particle chemical analysis of ambient ultrafine aerosol: A review, J. Aerosol Sci., 52, 109–120, https://doi.org/10.1016/j.jaerosci.2012.05.001, 2012.
Calvo, A. I., Alves, C., Castro, A., Pont, V., Vicente, A. M., and Fraile, R.: Research on aerosol sources and chemical composition: Past, current and emerging issues, Atmos. Res., 120–121, 1–28, https://doi.org/10.1016/j.atmosres.2012.09.021, 2013.
Castanho, D. A. and Artaxo, P.: Wintertime and summertime São Paulo aerosol source apportionment study, Atmos. Environ., 35, 4889–4902, https://doi.org/10.1016/s1352-2310(01)00357-0, 2001.
Cheung, H. C., Morawska, L., and Ristovski, Z. D.: Observation of new particle formation in subtropical urban environment, Atmos. Chem. Phys., 11, 3823–3833, https://doi.org/10.5194/acp-11-3823-2011, 2011.
Dal Maso, M., Kulmala, M., Riipinen, I., Wagner, R., Hussein, T., Aalto, P. P., and Lehtinen, K. E. J. Formation and growth of fresh atmospheric aerosols: eight years of aerosol size distribution data from SMEAR II, Hyytiala, Finland, Boreal Environ. Res., 10, 323–336, 2005.
Deng, Z. Z., Zhao, C. S., Ma, N., Ran, L., Zhou, G. Q., Lu, D. R., and Zhou, X. J.: An examination of parameterizations for the CCN number concentration based on in situ measurements of aerosol activation properties in the North China Plain, Atmos. Chem. Phys., 13, 6227–6237, https://doi.org/10.5194/acp-13-6227-2013, 2013.
Donahue, N. M., Ortega, I. K., Chuang, W., Riipinen, I., Riccobono, F., Schobesberger, S., Dommen, J., Baltensperger, U., Kulmala, M., Worsnopbe, D. R., and Vehkamaki, H.: How do organic vapors contribute to new-particle formation?, Faraday Discuss., 165, 91–104, https://doi.org/10.1039/c3fd00046j, 2013.
Draxler, R. and Hess G.: Description of the hysplit 4 modeling system, NOAA Tech. Memo. ERL ARL-224, NOAA Air Resources Laboratory, available at: http://ready.arl.noaa.gov/HYSPLIT.php, last access: 2 December 2003.
Draxler, R. and Rolph, G: HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) Model, NOAA Air Resources Laboratory, available at: http://www.arl.noaa.gov/ready/hysplit4.html, last access: 20 November 2015.
Dusek, U., Frank, G. P., Curtius, J., Drewnick, F., Schneider, J., Kürten, A., and Pöschl, U.: Enhanced organic mass fraction and decreased hygroscopicity of cloud condensation nuclei (CCN) during new particle formation events, Geophys. Res. Lett., 37, L03804, https://doi.org/10.1029/2009gl040930, 2010.
CETESB, Environmental Protection Agency of São Paulo Estate: Air quality report for the State of São Paulo 2015, available at: http://ar.cetesb.sp.gov.br/publicacoes-relatorios/ (last access: 10 June 2016), 2015 (in Portuguese).
Fernald, F. G.: Analysis of atmospheric lidar observations: some comments, Appl. Optics, 23, 652–653, https://doi.org/10.1364/AO.23.000652, 1984.
Frank, G. P., Dusek, U., and Andreae, M. O.: Technical note: A method for measuring size-resolved CCN in the atmosphere, Atmos. Chem. Phys. Discuss., 6, 4879–4895, https://doi.org/10.5194/acpd-6-4879-2006, 2006.
Freitas, E. D., Rozoff, C. M., and Cotton, W. R.: Interactions of an urban heat island and sea-breeze circulations during winter over the metropolitan area of São Paulo, Brazil, Bound.-Lay. Meteorol., 122, 43–65, https://doi.org/10.1007/s10546-006-9091-3, 2007.
Freud, E., Rosenfeld, D., Andreae, M. O., Costa, A. A., and Artaxo, P.: Robust relations between CCN and the vertical evolution of cloud drop size distribution in deep convective clouds, Atmos. Chem. Phys., 8, 1661–1675, https://doi.org/10.5194/acp-8-1661-2008, 2008.
Furutani, H., Dall, M., Roberts, G. C., and Prather, K. A.: Assessment of the relative importance of atmospheric aging on CCN activity derived from field observations, Atmos. Environ., 42, 3130–3142, https://doi.org/10.1016/j.atmosenv.2007.09.024, 2008.
Gioia, S. M. C. L., Babinski, M., Weiss, D. J., and Kerr, A. A. F. S.: Insights into the dynamics and sources of atmospheric lead and particulate matter in São Paulo, Brazil, from high temporal resolution sampling, Atmos. Res., 98, 478–485, https://doi.org/10.1016/j.atmosres.2010.08.016, 2010.
Gómez-Moreno, F. J., Pujadas, M., Plaza, J., Rodríguez-Maroto, J. J., Martínez-Lozano, P., and Artíñano, B.: Influence of seasonal factors on the atmospheric particle number concentration and size distribution in Madrid, Atmos. Environ., 45, 3169–3180, https://doi.org/10.1016/j.atmosenv.2011.02.041, 2011.
Guerrero-Rascado, J. L., Landulfo, E., Antuña, J. C., Barbosa, H. M. J., Barja, B, Bastidas, A. E., Bedoya, A. E., da Costa, R. F., Estevan, R., Forno, R. N., Gouveia, D. A., Jimenez, C., Larroza, E. G., Lopes, F. J. S., Montilla-Rosero, E., Moreira, G. A., Nakaema, W. M., Nisperuza, D., Alegria, D., Múnera, M., Otero, L., Papandrea, S., Pawelko, E., Quel, E. J., Ristori, P., Rodrigues, P. F., Salvador, J., Sánchez, M. F., and Silva, A.: Towards an instrumental harmonization in the framework of LALINET: dataset of technical specifications, Proc. SPIE 9246, Lidar Technologies, Techniques, and Measurements for Atmospheric Remote Sensing X, 92460O, https://doi.org/10.1117/12.2066873, 2014.
Guerrero-Rascado, J. L., Landulfo, E., Antuña, J. C., Barbosa, H. M. J., Barja, B, Bastidas, A. E., Bedoya, A. E., da Costa, R. F., Estevan, R., Forno, R. N., Gouveia, D. A., Jimenez, C., Larroza, E. G., Lopes, F. J. S., Montilla-Rosero, E., Moreira, G. A., Nakaema, W. M., Nisperuza, D., Alegria, D., Múnera, M., Otero, L., Papandrea, S., Pawelko, E., Quel, E. J., Ristori, P., Rodrigues, P. F., Salvador, J., Sánchez, M. F., and Silva, A.: Latin American Lidar Network (LALINET) for aerossol research: Diagnosis on network instrumentation, J. Atmos. Sol.-Terr. Phy., 138–139, 112–120, https://doi.org/10.1016/j.jastp.2016.01.001, 2016.
Gunthe, S. S., Rose, D., Su, H., Garland, R. M., Achtert, P., Nowak, A., Wiedensohler, A., Kuwata, M., Takegawa, N., Kondo, Y., Hu, M., Shao, M., Zhu, T., Andreae, M. O., and Pöschl, U.: Cloud condensation nuclei (CCN) from fresh and aged air pollution in the megacity region of Beijing, Atmos. Chem. Phys., 11, 11023–11039, https://doi.org/10.5194/acp-11-11023-2011, 2011.
Hallquist, M., Wenger, J. C., Baltensperger, U., Rudich, Y., Simpson, D., Claeys, M., Dommen, J., Donahue, N. M., George, C., Goldstein, A. H., Hamilton, J. F., Herrmann, H., Hoffmann, T., Iinuma, Y., Jang, M., Jenkin, M. E., Jimenez, J. L., Kiendler-Scharr, A., Maenhaut, W., McFiggans, G., Mentel, Th. F., Monod, A., Prévôt, A. S. H., Seinfeld, J. H., Surratt, J. D., Szmigielski, R., and Wildt, J.: The formation, properties and impact of secondary organic aerosol: current and emerging issues, Atmos. Chem. Phys., 9, 5155–5236, https://doi.org/10.5194/acp-9-5155-2009, 2009.
Heal, M. R., Kumar, P., and Harrison, R. M.: Particles, Air Quality, Policy and Health, Chem. Soc. Rev., 41, 6606–6630, https://doi.org/10.1039/c2cs35076a, 2012.
Hetem, I. G. and Andrade, M. F.: Characterization of fine particulate matter emitted from the resuspension of road and pavement dust in the Metropolitan Area of São Paulo, Brazil, Atmosphere, 7, 31–41, https://doi.org/10.3390/atmos7030031, 2016.
Holben, B. N., Eck, T. F., Slutsker, I., Tanré, D., Buis, J. P., Setzer, A., Vermote, E., Reagan, J. A., Kaufman, Y. J., Nakajima, T., Lavenu, T. Jankowiak, I., and Smirnov, A.: Aeronet – A Federal Instrument Network and Data Archive for Aerosol Characterization, Remote Sens. Environ., 66, 1–16, https://doi.org/10.1016/S0034-4257(98)00031-5, 1998.
Holmes, N. S.: A review of particle formation events and growth in the atmosphere in the various environments and discussion of mechanistic implications, Atmos. Environ., 41, 2183–2201, https://doi.org/10.1016/j.atmosenv.2006.10.058, 2007.
IBGE, Brazilian Institute of Geography and Statistics: Atlas of the 2010 Population Census, available at: http://www.ibge.gov.br/english/ (last access: 1 January 2016), 2010.
IPCC: Climate change 2013, Scientific basis, Fifth assessment of the Intergovernmental Panel on Climate Change, available at: http://www.ipcc.ch/report/ar5/wg1/ (last access: 10 February 2015), 2013.
Kalafut-Pettibone, A. J., Wang, J., Eichinger, W. E., Clarke, A., Vay, S. A., Blake, D. R., and Stanier, C. O.: Size-resolved aerosol emission factors and new particle formation/growth activity occurring in Mexico City during the MILAGRO 2006 Campaign, Atmos. Chem. Phys., 11, 8861–8881, https://doi.org/10.5194/acp-11-8861-2011, 2011.
Karavalakis, G., Boutsika, V., Stournas, S., and Bakeas, E.: Biodiesel emissions profile in modern diesel vehicles. Part 2: Effect of biodiesel origin on carbonyl, PAH, nitro-PAH and oxy-PAH emissions, Sci. Total Environ., 409, 938–747, https://doi.org/10.1016/j.scitotenv.2010.11.010, 2011.
Klett, J. D.: Stable analytical inversion solution for processing lidar returns, Appl. Optics, 20, 211–220, https://doi.org/10.1364/ao.20.000211, 1981.
Klett, J. D.: Lidar calibration and extinction coefficients, Appl. Optics, 22, 514–515, https://doi.org/10.1364/ao.22.000514, 1983.
Kroll, J. H. and Seinfeld, J. H.: Chemistry of secondary organic aerosol: Formation and evolution of low-volatility organics in the atmosphere, Atmos. Environ., 42, 3593–3624, https://doi.org/10.1016/j.atmosenv.2008.01.003, 2008.
Kulmala, M., Vehkamaki, H., Petäjä, T., Dal Maso, M., Lauri, A., Kerminen, V. M., Birmili, W., and McMurry, P. H.: Formation and growth rates of ultrafine atmospheric particles: a review of observations, J. Aerosol Sci., 35, 143–176, https://doi.org/10.1016/j.jaerosci.2003.10.003, 2004.
Kumar, P., Robins, A., Vardoulakis, S., and Britter, R.: A review of the characteristics of nanoparticles in the urban atmosphere and the prospects for developing regulatory control, Atmos. Environ., 44, 5035–5052, https://doi.org/10.1016/j.atmosenv.2010.08.016, 2010.
Kumar, P., Morawska, L., Birmili, W., Paasonen, P., Hu, M., Kulmala, M., Harrison, R. M., Norford, L., and Britter, R.: Ultrafine particles in cities, Environ. Int., 66, 1–10, https://doi.org/10.1016/j.envint.2014.01.013, 2014.
Kumar, P., Andrade, M. F., Ynoue, R. Y., Fornaro, A., de Freitas, E. D., Martins, J., Martins, L. D., Albuquerque, T., Zhang, Y., and Morawska, L.: New Directions: From biofuels to wood stoves: the modern and ancient air quality challenges in the megacity of São Paulo, Atmos. Environ., 140, 364–369, https://doi.org/10.1016/j.atmosenv.2016.05.059, 2016.
Leng, C., Cheng, T., Chen, J., Zhang, R., Tao, J., Huang, G., and Li, L.: Measurements of surface cloud condensation nuclei and aerosol activity in downtown Shanghai, Atmos. Environ., 69, 354–361, https://doi.org/10.1016/j.atmosenv.2012.12.021, 2013.
Long, B., Tan, X. F., Wang, Y. B., Li, J., Ren, D. S., and Zhang, W. J.: Theoretical Studies on Reactions of OH with H2SO4⋯NH3 Complex and NH2 with H2SO4 in the Presence of Water, Chemistry Select, 1, 1421–1430, https://doi.org/10.1002/slct.201600194, 2016.
Ma, N. and Birmili, W.: Estimating the contribution of photochemical particle formation to ultrafine particle number averages in an urban atmosphere, Sci. Total Environ., 512, 154–166, https://doi.org/10.1016/j.scitotenv.2015.01.009, 2015.
Marenco, F., Santacesaria, V., Bais, A. F., Balis, D., di Sarra, A., Papayannis, A., and Zerefos, C.: Optical properties of tropospheric aerosols determined by lidar and spectrophotometric measurements (Photochemical Activity and Solar Ultraviolet Radiation campaign), Appl. Optics, 36, 6875–6886, https://doi.org/10.1364/AO.36.006875, 2002.
McFiggans, G., Artaxo, P., Baltensperger, U., Coe, H., Facchini, M. C., Feingold, G., Fuzzi, S., Gysel, M., Laaksonen, A., Lohmann, U., Mentel, T. F., Murphy, D. M., O'Dowd, C. D., Snider, J. R., and Weingartner, E.: The effect of physical and chemical aerosol properties on warm cloud droplet activation, Atmos. Chem. Phys., 6, 2593–2649, https://doi.org/10.5194/acp-6-2593-2006, 2006.
Metzger, A., Verheggen, B., Dommen, J., Duplissy, J., Prevot, A. S. H., Weingartner, E., Riipinenc, I., Kulmalac, M., Spracklend, D. V., Carslawd, K. S., and Baltensperger, U.: Evidence for the role of organics in aerosol particle formation under atmospheric conditions, P. Natl. Acad. Sci. USA, 107, 6646–6651, https://doi.org/10.1073/pnas.0911330107, 2010.
Monks, P. S., Archibald, A. T., Colette, A., Cooper, O., Coyle, M., Derwent, R., Fowler, D., Granier, C., Law, K. S., Mills, G. E., Stevenson, D. S., Tarasova, O., Thouret, V., von Schneidemesser, E., Sommariva, R., Wild, O., and Williams, M. L.: Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer, Atmos. Chem. Phys., 15, 8889–8973, https://doi.org/10.5194/acp-15-8889-2015, 2015.
Müller, D., Ansmann, A., Mattis, I., Tesche, M., Wandinger, U., Althausen, D., and Pisani, G.: Aerosol-type-dependent lidar ratios observed with raman lidar, J. Geophys. Res., 112, D16202, https://doi.org/10.1029/2006jd008292, 2007.
Nie, W., Ding, A., Wang, T., Kerminen, V.-M., George, C., Xue, L., and Kulmala, M.: Polluted dust promotes new particle formation and growth, Nature, 4, 6634, https://doi.org/10.1038/srep06634, 2014.
Oliveira, A. P., Bornstein, R. D., and Soares, J.: Annual and diurnal wind patterns in the city of São Paulo, Water Air Soil Poll., 3, 3–15, https://doi.org/10.1023/A:1026090103764, 2003.
Ortega, A. M., Hayes, P. L., Peng, Z., Palm, B. B., Hu, W., Day, D. A., Li, R., Cubison, M. J., Brune, W. H., Graus, M., Warneke, C., Gilman, J. B., Kuster, W. C., de Gouw, J., Gutiérrez-Montes, C., and Jimenez, J. L.: Real-time measurements of secondary organic aerosol formation and aging from ambient air in an oxidation flow reactor in the Los Angeles area, Atmos. Chem. Phys., 16, 7411–7433, https://doi.org/10.5194/acp-16-7411-2016, 2016.
Oyama, B. S., Andrade, M. F., Herckes, P., Dusek, U., Röckmann, T., and Holzinger, R.: Vehicular emissions of organic particulate matter in Sao Paulo, Brazil, Atmos. Chem. Phys. Discuss., 15, 33755–33788, https://doi.org/10.5194/acpd-15-33755-2015, 2015.
Paramonov, M., Aalto, P. P., Asmi, A., Prisle, N., Kerminen, V.-M., Kulmala, M., and Petäjä, T.: The analysis of size-segregated cloud condensation nuclei counter (CCNC) data and its implications for cloud droplet activation, Atmos. Chem. Phys., 13, 10285–10301, https://doi.org/10.5194/acp-13-10285-2013, 2013.
Peng, J. F., Hu, M., Wang, Z. B., Huang, X. F., Kumar, P., Wu, Z. J., Guo, S., Yue, D. L., Shang, D. J., Zheng, Z., and He, L. Y.: Submicron aerosols at thirteen diversified sites in China: size distribution, new particle formation and corresponding contribution to cloud condensation nuclei production, Atmos. Chem. Phys., 14, 10249–10265, https://doi.org/10.5194/acp-14-10249-2014, 2014.
Pierce, J. R., Leaitch, W. R., Liggio, J., Westervelt, D. M., Wainwright, C. D., Abbatt, J. P. D., Ahlm, L., Al-Basheer, W., Cziczo, D. J., Hayden, K. L., Lee, A. K. Y., Li, S.-M., Russell, L. M., Sjostedt, S. J., Strawbridge, K. B., Travis, M., Vlasenko, A., Wentzell, J. J. B., Wiebe, H. A., Wong, J. P. S., and Macdonald, A. M.: Nucleation and condensational growth to CCN sizes during a sustained pristine biogenic SOA event in a forested mountain valley, Atmos. Chem. Phys., 12, 3147–3163, https://doi.org/10.5194/acp-12-3147-2012, 2012.
Quinn, P. K., Bates, T. S., Coffman, D. J., and Covert, D. S.: Influence of particle size and chemistry on the cloud nucleating properties of aerosols, Atmos. Chem. Phys., 8, 1029–1042, https://doi.org/10.5194/acp-8-1029-2008, 2008.
Reade, L., Jennings, S. G., and McSweeney, G.: Cloud condensation nuclei measurements at Mace Head, Ireland, over the period 1994–2002, Atmos. Res., 82, 610–621, https://doi.org/10.1016/j.atmosres.2006.02.017, 2006.
Reche, C., Querol, X., Alastuey, A., Viana, M., Pey, J., Moreno, T., Rodríguez, S., González, Y., Fernández-Camacho, R., de la Rosa, J., Dall'Osto, M., Prévôt, A. S. H., Hueglin, C., Harrison, R. M., and Quincey, P.: New considerations for PM, Black Carbon and particle number concentration for air quality monitoring across different European cities, Atmos. Chem. Phys., 11, 6207–6227, https://doi.org/10.5194/acp-11-6207-2011, 2011.
Reff, A., Eberly, S. I., and Bhave, P. V.: Receptor Modeling of Ambient Particulate Matter Data Using Positive Matrix Factorization: Review of Existing Methods Receptor Modeling of Ambient Particulate Matter Data Using Positive Matrix Factorization, J. Air Waste Manage., 57, 146–154, https://doi.org/10.1080/10473289.2007.10465319, 2007.
Remer, L. A., Kaufman, Y. J., Tanré, D., Mattoo, S., Chu, D. A., Martins, J. V., Li, R. R., Ichoku, C., Levy, R. C., Kleidman, R. G., Eck, T. F., Vermote, E., and Holben, B. N.: The MODIS aerosol algorithm, products, and validation, J. Atmos. Sci., 62, 947–973, https://doi.org/10.1175/JAS3385.1, 2005.
Riipinen, I., Pierce, J. R., Yli-Juuti, T., Nieminen, T., Häkkinen, S., Ehn, M., Junninen, H., Lehtipalo, K., Petäjä, T., Slowik, J., Chang, R., Shantz, N. C., Abbatt, J., Leaitch, W. R., Kerminen, V.-M., Worsnop, D. R., Pandis, S. N., Donahue, N. M., and Kulmala, M.: Organic condensation: a vital link connecting aerosol formation to cloud condensation nuclei (CCN) concentrations, Atmos. Chem. Phys., 11, 3865–3878, https://doi.org/10.5194/acp-11-3865-2011, 2011.
Roberts, G. C. and Nenes, A.: A Continuous-Flow Streamwise Thermal-Gradient CCN Chamber for Atmospheric Measurements, Aerosol Sci. Technol., 39, 206–221, https://doi.org/10.1080/027868290913988, 2005.
Rodrigues, P. F., Landulfo, E., Gandu, A. W., and Lopes, F. J. S.: Assessment of aerosol hygroscopic growth using an elastic LIDAR and BRAMS simulation in urban metropolitan areas, AIP Conf. Proc., 1531, 360–363, https://doi.org/10.1063/1.4804781, 2013.
Sanchez-Ccoyllo, O. R. and Andrade, M. F.: The influence of meteorological conditions on the behavior of pollutants concentrations in São Paulo, Brazil, Environ. Pollut., 116, 257–263, https://doi.org/10.1016/S0269-7491(01)00129-4, 2002.
Sánchez-Ccoyllo, O. R., Ynoue, R. Y., Martins, L. D., Astolfo, R., Miranda, R. M., Freitas, E. D., Borges, A. S., Fornaro, A., Freitas, H., Moreira, A., and Andrade, M. F.: Vehicular particulate matter emissions in road tunnels in São Paulo, Brazil, Environ. Monit. Assess., 149, 241–249, https://doi.org/10.1007/s10661-008-0198-5, 2008.
Sasano, Y. and Nakane, H.: Significance of the extinction/backscatter ratio and the boundary value term in the solution for the two-component lidar equation, Appl. Optics, 23, 1–13, https://doi.org/10.1364/AO.23.0011_1, 1984.
Shilling, J. E., Zaveri, R. A., Fast, J. D., Kleinman, L., Alexander, M. L., Canagaratna, M. R., Fortner, E., Hubbe, J. M., Jayne, J. T., Sedlacek, A., Setyan, A., Springston, S., Worsnop, D. R., and Zhang, Q.: Enhanced SOA formation from mixed anthropogenic and biogenic emissions during the CARES campaign, Atmos. Chem. Phys., 13, 2091–2113, https://doi.org/10.5194/acp-13-2091-2013, 2013.
Sihto, S.-L., Mikkilä, J., Vanhanen, J., Ehn, M., Liao, L., Lehtipalo, K., Aalto, P. P., Duplissy, J., Petäjä, T., Kerminen, V.-M., Boy, M., and Kulmala, M.: Seasonal variation of CCN concentrations and aerosol activation properties in boreal forest, Atmos. Chem. Phys., 11, 13269–13285, https://doi.org/10.5194/acp-11-13269-2011, 2011.
Silva, M. F., Assunção, J. V., Andrade, M. F., and Pesquero, C.: Characterization of metal and trace element contents of particulate matter (PM10) emitted by vehicles running on Brazilian fuels – hydrated ethanol and gasoline with 22 % of anhydrous ethanol, J. Toxicol. Env. Health, A73, 901–909, https://doi.org/10.1080/15287391003744849, 2010.
Sorribas, M., Adame, J. A., Olmo, F. J., Vilaplana, J. M., Gil-Ojeda, M., and Alados-Arboledas, L.: A long-term study of new particle formation in a coastal environment: meteorology, gas phase and solar radiation implications, Sci. Total Environ., 511, 723–37, https://doi.org/10.1016/j.scitotenv.2014.12.011, 2015.
Taiwo, A. M., Harrison, R. M., and Shi, Z.: A review of receptor modelling of industrially emitted particulate matter, Atmos. Environ., 97, 109–120, https://doi.org/10.1016/j.atmosenv.2014.07.051, 2014.
Vara-Vela, A., Andrade, M. F., Kumar, P., Ynoue, R. Y., and Muñoz, A. G.: Impact of vehicular emissions on the formation of fine particles in the Sao Paulo Metropolitan Area: a numerical study with the WRF-Chem model, Atmos. Chem. Phys., 16, 777–797, https://doi.org/10.5194/acp-16-777-2016, 2016.
Wallington, T. J., Anderson, J., Kurtz, E. M., and Tennison P. J.: Biofuels, vehicle emissions, and urban air quality, Faraday Discuss., 189, 121–136, https://doi.org/10.1039/c5fd00205b, 2016.
Yuan, B., Hu, W. W., Shao, M., Wang, M., Chen, W. T., Lu, S. H., Zeng, L. M., and Hu, M.: VOC emissions, evolutions and contributions to SOA formation at a receptor site in eastern China, Atmos. Chem. Phys., 13, 8815–8832, https://doi.org/10.5194/acp-13-8815-2013, 2013.
Yue, D. L., Hu, M., Zhang, R. Y., Wu, Z. J., Su, H., Wang, Z. B., and Wiedensohler, A.: Potential contribution of new particle formation to cloud condensation nuclei in Beijing, Atmos. Environ., 45, 6070–6077, https://doi.org/10.1016/j.atmosenv.2011.07.037, 2011.
Yum, S. S., James, G. H., Keun, Y. S., and Byoung-Cheol, C.: Springtime cloud condensation nuclei concentrations on the west coast of Korea, Geophys. Res. Lett., 32, L09814, https://doi.org/10.1029/2005gl022641, 2005.
Zhang, F., Li, Y., Li, Z., Sun, L., Li, R., Zhao, C., Wang, P., Sun, Y., Liu, X., Li, J., Li, P., Ren, G., and Fan, T.: Aerosol hygroscopicity and cloud condensation nuclei activity during the AC3Exp campaign: implications for cloud condensation nuclei parameterization, Atmos. Chem. Phys., 14, 13423–13437, https://doi.org/10.5194/acp-14-13423-2014, 2014.
Zhu, Y., Sabaliauskas, K., Liu, X., Meng, H., Gao, H., Jeong, C. H., Evans, G. J., and Yao, X.: Comparative analysis of new particle formation events in less and severely polluted urban atmosphere, Atmos. Environ., 98, 655–664, https://doi.org/10.1016/j.atmosenv.2014.09.043, 2014.
The Metropolitan Area of São Paulo is the biggest megacity of South America, with over 20 million inhabitants. In recent years, the region has been facing a modification in rain patterns. In this study, we evaluated the effects of local and remote sources of air pollution on cloud-condensation nuclei activation properties. Our results showed that the local vehicular traffic emission products presented more negative effects on cloud-condensation nuclei activation than the remote sources.
The Metropolitan Area of São Paulo is the biggest megacity of South America, with over 20...