Homogeneous nucleation and subsequent cluster growth leads to the formation of new aerosol particles in the atmosphere. The nucleation of sulfuric acid and organic vapours is thought to be responsible for the formation of new particles over continents, whereas iodine oxide vapours have been implicated in particle formation over coastal regions. The molecular clustering pathways that are involved in atmospheric particle formation have been elucidated in controlled laboratory studies of chemically simple systems, but direct molecular-level observations of nucleation in atmospheric field conditions that involve sulfuric acid, organic or iodine oxide vapours have yet to be reported. Here we present field data from Mace Head, Ireland, and supporting data from northern Greenland and Queen Maud Land, Antarctica, that enable us to identify the molecular steps involved in new particle formation in an iodine-rich, coastal atmospheric environment. We find that the formation and initial growth process is almost exclusively driven by iodine oxoacids and iodine oxide vapours, with average oxygen-to-iodine ratios of 2.4 found in the clusters. On the basis of this high ratio, together with the high concentrations of iodic acid (HIO) observed, we suggest that cluster formation primarily proceeds by sequential addition of HIO, followed by intracluster restructuring to I O and recycling of water either in the atmosphere or on dehydration. Our study provides ambient atmospheric molecular-level observations of nucleation, supporting the previously suggested role of iodine-containing species in the formation of new aerosol particles, and identifies the key nucleating compound.

Sipilä Mikko    Sarnela Nina    Jokinen    Henschel Henning    Heikki Junninen    Kontkanen Jenni    Richters    Juha Kangasluoma    Alessandro Franchin    Otso Peräkylä O    Rissanen Matti    Ehn    Hanna Vehkamäki    Kurtén    Berndt Torsten    Tuukka Petäj̈ä T.    Douglas Worsnop    Ceburnis Darius    Veli matti Kerminen    Markku Kulmala     Colin O.'Dowd   

Nature

2016

This work presents an overall introduction to the Station for Observing Regional Processes of the Earth System–SORPES in Nanjing, East China, and gives an overview about main scientific findings in studies of air pollution-weather/climate interactions obtained since 2011. The main results summarized in this paper include overall characteristics of trace gases and aerosols, chemical transformation mechanisms for secondary pollutants like O, HONO and secondary inorganic aerosols, and the air pollution–weather/climate interactions and feedbacks in mixed air pollution plumes from sources like fossil fuel combustion, biomass burning and dust storms. The future outlook of the development plan on instrumentation, networking and data-sharing for the SORPES station is also discussed. [Figure not available: see fulltext.]

丁爱军    Wei Nie    黄昕    Xuguang Chi    Sun    Veli matti Kerminen    Xu    Guo    Tuukka Petäj̈ä T.    杨修群    Markku Kulmala     Congbin Fu   

Frontiers of Environmental Science and Engineering

2016

The northern Eurasian regions and Arctic Ocean will very likely undergo substantial changes during the next decades. The Arctic-boreal natural environments play a crucial role in the global climate via albedo change, carbon sources and sinks as well as atmospheric aerosol production from biogenic volatile organic compounds. Furthermore, it is expected that global trade activities, demographic movement, and use of natural resources will be increasing in the Arctic regions. There is a need for a novel research approach, which not only identifies and tackles the relevant multi-disciplinary research questions, but also is able to make a holistic system analysis of the expected feedbacks. In this paper, we introduce the research agenda of the Pan-Eurasian Experiment (PEEX), a multi-scale, multi-disciplinary and international program started in 2012 (https://www.atm.helsinki.fi/peex/). PEEX sets a research approach by which large-scale research topics are investigated from a system perspective and which aims to fill the key gaps in our understanding of the feedbacks and interactions between the land-Atmosphere-Aquatic-society continuum in the northern Eurasian region. We introduce here the state of the art for the key topics in the PEEX research agenda and present the future prospects of the research, which we see relevant in this context.

Lappalainen    Veli matti Kerminen    Tuukka Petäj̈ä T.    Kurtén    Baklanov Aleksander    Anatoly Shvidenko    Bäck    Vihma Timo    Alekseychik Pavel    Meinrat Andreae    Arnold Stephen R.    Arshinov    Asmi    Belan    Bobylev Leonid    Chalov Sergey    程雅芳    Chubarova Natalia    De Leeuw    丁爱军    Dobrolyubov Sergey    Dubtsov Sergei    Dyukarev Egor    Elansky Nikolai    Konstantinos Eleftheriadis    Esau Igor    Filatov Nikolay    Flint Mikhail V.    Congbin Fu    Glezer Olga    Gliko Aleksander    Heimann    Holtslag    Hõrrak Urmas    Juha Janhunen    Juhola    Järvi Leena    Järvinen    Kanukhina Anna    Konstantinov Pavel    Vladimir Kotlyakov    Kieloaho    Komarov Alexander S.    Kujansuu    Kukkonen Ilmo    Duplissy Ella-Maria    Ari Laaksonen    Laurila    Lihavainen Heikki    Lisitzin Alexander    Mahura Alexander    Makshtas Alexander P.    Mareev Evgeny    Mazon Stephany    Matishov Dmitry    Melnikov Vladimir    Mikhailov    Dmitri Moisseev    Nigmatulin Robert    Noe    Ojala Anne    Pihlatie Mari    Popovicheva Olga    Pumpanen    Regerand Tatjana    Repina Irina    Shcherbinin    Shevchenko Vladimir    Sipilä Mikko    Skorokhod Andrey    Dominick Spracklen    Hang Su    Subetto Dmitry    Sun Junying    Terzhevik Arkady Y.    Timofeyev Yuri    Troitskaya Yuliya    Tynkkynen    Kharuk Viacheslav    Zaytseva Nina    Zhang Jiahua    Viisanen Yrjö    Timo Vesala    Pertti pepe Hari    Christen Hansson Hans    Matvienko Gennady G.    Kasimov    Guo Huadong    Bondur    Sergej Zilitinkevich    Markku Kulmala    

Atmospheric Chemistry and Physics

2016

We derive a version of Classical Nucleation Theory normalized by quantum chemical results on sulfuric acid-water hydration to describe neutral and ion-induced particle formation in the binary sulfuric acid-water system. The theory is extended to treat the kinetic regime where the nucleation free energy barrier vanishes at high sulfuric acid concentrations or low temperatures. In the kinetic regime particle formation rates become proportional to sulfuric acid concentration to second power in the neutral system or first power in the ion-induced system. We derive simple general expressions for the prefactors in kinetic-type and activation-type particle formation calculations applicable also to more complex systems stabilized by other species. The theory predicts that the binary water-sulfuric acid system can produce strong new particle formation in the free troposphere both through barrier crossing and through kinetic pathways. At cold stratospheric and upper free tropospheric temperatures neutral formation dominates the binary particle formation rates. At midtropospheric temperatures the ion-induced pathway becomes the dominant mechanism. However, even the ion-induced binary mechanism does not produce significant particle formation in warm boundary layer conditions, as it requires temperatures below 0°C to take place at atmospheric concentrations. The theory successfully reproduces the characteristics of measured charged and neutral binary particle formation in CERN CLOUD3 and CLOUD5 experiments, as discussed in a companion paper.

Merikanto Joonas    Jonathan Duplissy    Määttänen Anni    Henschel Henning    Neil mc pherson Donahue    Brus    Siegfried Schobesberger    Markku Kulmala     Hanna Vehkamäki   

Journal of Geophysical Research: Atmospheres

2016

An advanced along-track scanning radiometer (AATSR) global multi-year aerosol retrieval algorithm is described. Over land, the AATSR dual-view (ADV) algorithm utilizes the measured top of the atmosphere (TOA) reflectance in both the nadir and forward views to decouple the contributions of the atmosphere and the surface to retrieve aerosol properties. Over ocean, the AATSR single-view (ASV) algorithm minimizes the discrepancy between the measured and modelled TOA reflectances in one of the views to retrieve the aerosol information using an ocean reflectance model. Necessary steps to process global, multi-year aerosol information are presented. These include cloud screening, the averaging of measured reflectance, and post-processing. Limitations of the algorithms are also discussed. The main product of the aerosol retrieval is the aerosol optical depth (AOD) at visible/near-infrared wavelengths. The retrieved AOD is validated using data from the surface-based AERONET and maritime aerosol network (MAN) sun photometer networks as references. The validation shows good agreement with the reference (r = 0.85, RMSE = 0.09 over land; r = 0.83, RMSE = 0.09 at coasts and r = 0.96, RMSE = 0.06 over open ocean). The results of the aerosol retrievals are presented for the full AATSR mission years 2002–2012 with seasonally averaged time series for selected regions.

Kolmonen    Sogacheva Larisa    Virtanen    De Leeuw    Markku Kulmala    

International Journal of Digital Earth

2016

We simulated the time evolution of atmospheric cluster concentrations in a one-component system where not only do clusters grow by condensation of monomers, but cluster-cluster collisions also significantly contribute to the growth of the clusters. Our aim was to investigate the consistency of the growth rates of sub-3 nm clusters determined with different methods and the validity of the common approach to use them to estimate particle formation rates. We compared the growth rate corresponding to particle fluxes (FGR), the growth rate derived from the appearance times of clusters (AGR), and the growth rate calculated based on irreversible vapor condensation (CGR). We found that the relation between the different growth rates depends strongly on the external conditions and the properties of the model substance. The difference between the different growth rates was typically highest at the smallest, sub-2 nm sizes. FGR was generally lower than AGR and CGR; at the smallest sizes the difference was often very large, while at sizes larger than 2 nm the growth rates were closer to each other. AGR and CGR were in most cases close to each other at all sizes. The difference between the growth rates was generally lower in conditions where cluster concentrations were high, and evaporation and other losses were thus less significant. Furthermore, our results show that the conventional method used to determine particle formation rates from growth rates may give estimates far from the true values. Thus, care must be taken not only in how the growth rate is determined but also in how it is applied.

Kontkanen Jenni    Olenius    Lehtipalo    Hanna Vehkamäki    Markku Kulmala     J. Lehtinen K.   

Atmospheric Chemistry and Physics

2016

Disproportional warming in the northern high latitudes and large carbon stocks in boreal and (sub)arctic ecosystems have raised concerns as to whether substantial positive climate feedbacks from biogeochemical process responses should be expected. Such feedbacks occur when increasing temperatures lead, for example, to a net release of CO or CH. However, temperature-enhanced emissions of biogenic volatile organic compounds (BVOCs) have been shown to contribute to the growth of secondary organic aerosol (SOA), which is known to have a negative radiative climate effect. Combining measurements in Eastern Siberia with model-based estimates of vegetation and permafrost dynamics, BVOC emissions, and aerosol growth, we assess here possible future changes in ecosystem CO balance and BVOC-SOA interactions and discuss these changes in terms of possible climate effects. Globally, the effects of changes in Siberian ecosystem CO balance and SOA formation are small, but when concentrating on Siberia and the Northern Hemisphere the negative forcing from changed aerosol direct and indirect effects become notable - even though the associated temperature response would not necessarily follow a similar spatial pattern. While our analysis does not include other important processes that are of relevance for the climate system, the CO and BVOC-SOA interplay serves as an example for the complexity of the interactions between emissions and vegetation dynamics that underlie individual terrestrial processes and highlights the importance of addressing ecosystem-climate feedbacks in consistent, process-based model frameworks.

Almuth Arneth    Makkonen    Olin    Paasonen    Holst Thomas    Kajos    Markku Kulmala     Maximov    Miller    Guy Schurgers   

Atmospheric Chemistry and Physics

2016

Pinonaldehyde, which is among the most abundant oxidation products of α-pinene, and dimethylamine were selected to study the formation of N-containing low volatile compounds from aldehyde-amine reactions in the atmosphere. Gas phase reactions took place in a Tedlar bag, which was connected to a mass spectrometer ionization source via a short deactivated fused silica column. In addition to on-line analysis, abundance of gaseous precursors and reaction products were monitored off-line. Condensable products were extracted from the bags walls with a suitable solvent and analyzed by gas chromatography coupled to chemical ionization high-resolution quadrupole time-of-flight mass spectrometry and by ultra-high-performance liquid chromatography coupled to electrospray ionization Orbitrap mass spectrometry. The reactions carried out resulted in several mid-low vapor pressure nitrogen-containing compounds that are potentially important for the formation of secondary organic aerosols in the atmosphere. Further, the presence of brown carbon, confirmed by liquid chromatography-UV-vis-mass spectrometry, was observed. Some of the compounds identified in the laboratory study were also observed in aerosol samples collected at SMEAR II station (Hyytiälä, Finland) in August 2015 suggesting the importance of aldehyde-amine reactions for the aerosol formation and growth.

Duporté Geoffroy    Parshintsev Jevgeni    Barreira Luís Miguel Feijó    Hartonen Kari    Markku Kulmala     Marja liisa Riekkola   

Environmental Science and Technology

2016

We simulated the time evolution of atmospheric cluster concentrations in a one-component system where clusters grow not only by condensation of monomers, but where also cluster-cluster collisions significantly contribute to the growth of the clusters. Our aims were to investigate the consistency of the growth rates of sub-3 nm clusters determined with different methods, and the validity of the common approach to use them to estimate particle formation rates. We compared the growth rate corresponding to particle fluxes (FGR), the growth rate derived from the appearance times of clusters (AGR) and the growth rate calculated based on irreversible vapor condensation (CGR). We found that the relation between the different growth rates depends strongly on the external conditions and the properties of the model substance. The difference between the different growth rates was typically highest at the smallest, sub-2nm sizes. FGR was generally lower than AGR and CGR; at the smallest sizes the difference was often very large, while at sizes larger than 2 nm, the growth rates were closer to each other. AGR and CGR were in most cases close to each other at all sizes. The difference between the growth rates was generally lower in conditions where cluster concentrations were high, and evaporation and other losses thus less significant. Furthermore, our results show that the conventional method used to determine particle formation rates from growth rates may give estimates far from the true values. Thus, care must be taken not only in how the growth rate is determined, but also in how it is applied.

Kontkanen Jenni    Olenius    Lehtipalo    Hanna Vehkamäki    Markku Kulmala     J. Lehtinen K.   

Atmospheric Chemistry and Physics Discussions

2016

In this paper som periods of air pollution, observed in China during the recent years are analyzed. It i showed that high concentration of particulate matter (PM) minimizes the boundary layer height and leads to increasing pollutant concentrations. Critical number for concentration is 200 gm-after it feedback between boundary layer height and concentrations became stronger.

Tuukka Petäj̈ä T.    Järvi Leena    Veli matti Kerminen    Ding    Sun    Wei Nie    Kujansuu    Virkkula Aki    Yang    Fu    Konstantinov Pavel    Zilitinkevkh    Markku Kulmala    

Vestnik Moskovskogo Universiteta, Seriya 5: Geografiya

2016