Search Results
Causes and importance of new particle formation in the present-day and preindustrial atmospheres
2017, Gordon, Hamish, Kirkby, Jasper, Baltensperger, Urs, Bianchi, Federico, Breitenlechner, Martin, Curtius, Joachim, Dias, Antonio, Dommen, Josef, Donahue, Neil M., Dunne, Eimear M., Duplissy, Jonathan, Ehrhart, Sebastian, Flagan, Richard C., Frege, Carla, Fuchs, Claudia, Hansel, Armin, Hoyle, Christopher R., Kulmala, Markku, Kürten, Andreas, Lehtipalo, Katrianne, Makhmutov, Vladimir, Molteni, Ugo, Rissanen, Matti P., Stozkhov, Yuri, Tröstl, Jasmin, Tsagkogeorgas, Georgios, Wagner, Robert, Williamson, Christina, Wimmer, Daniela, Winkler, Paul M., Yan, Chao, Carslaw, Ken S.
New particle formation has been estimated to produce around half of cloud-forming particles in the present-day atmosphere, via gas-to-particle conversion. Here we assess the importance of new particle formation (NPF) for both the present-day and the preindustrial atmospheres. We use a global aerosol model with parametrizations of NPF from previously published CLOUD chamber experiments involving sulfuric acid, ammonia, organic molecules, and ions. We find that NPF produces around 67% of cloud condensation nuclei at 0.2% supersaturation (CCN0.2%) at the level of low clouds in the preindustrial atmosphere (estimated uncertainty range 45–84%) and 54% in the present day (estimated uncertainty range 38–66%). Concerning causes, we find that the importance of biogenic volatile organic compounds (BVOCs) in NPF and CCN formation is greater than previously thought. Removing BVOCs and hence all secondary organic aerosol from our model reduces low-cloud-level CCN concentrations at 0.2% supersaturation by 26% in the present-day atmosphere and 41% in the preindustrial. Around three quarters of this reduction is due to the tiny fraction of the oxidation products of BVOCs that have sufficiently low volatility to be involved in NPF and early growth. Furthermore, we estimate that 40% of preindustrial CCN0.2% are formed via ion-induced NPF, compared with 27% in the present day, although we caution that the ion-induced fraction of NPF involving BVOCs is poorly measured at present. Our model suggests that the effect of changes in cosmic ray intensity on CCN is small and unlikely to be comparable to the effect of large variations in natural primary aerosol emissions.
Ion-induced nucleation of pure biogenic particles
2016, Kirkby, Jasper, Duplissy, Jonathan, Sengupta, Kamalika, Gordon, Hamish, Williamson, Christina, Heinritzi, Martin, Simon, Mario, Yan, Chao, Almeida, João, Tröstl, Jasmin, Nieminen, Tuomo, Ortega, Ismael K., Wagner, Robert, Adamov, Alexey, Amorim, Antonio, Bernhammer, Anne-Kathrin, Bianchi, Federico, Breitenlechner, Martin, Brilke, Sophia, Chen, Xuemeng, Craven, Jill, Dias, Antonio, Ehrhart, Sebastian, Flagan, Richard C., Franchin, Alessandro, Fuchs, Claudia, Guida, Roberto, Hakala, Jani, Hoyle, Christopher R., Jokinen, Tuija, Junninen, Heikki, Kangasluoma, Juha, Kim, Jaeseok, Krapf, Manuel, Kürten, Andreas, Laaksonen, Ari, Lehtipalo, Katrianne, Makhmutov, Vladimir, Mathot, Serge, Molteni, Ugo, Onnela, Antti, Peräkylä, Otso, Piel, Felix, Petäjä, Tuukka, Praplan, Arnaud P., Pringle, Kirsty, Rap, Alexandru, Richards, Nigel A.D., Riipinen, Ilona, Rissanen, Matti P., Rondo, Linda, Sarnela, Nina, Schobesberger, Siegfried, Scott, Catherine E., Seinfeld, John H., Sipilä, Mikko, Steiner, Gerhard, Stozhkov, Yuri, Stratmann, Frank, Tomé, Antonio, Virtanen, Annele, Vogel, Alexander L., Wagner, Andrea C., Wagner, Paul E., Weingartner, Ernest, Wimmer, Daniela, Winkler, Paul M., Ye, Penglin, Zhang, Xuan, Hansel, Armin, Dommen, Josef, Donahue, Neil M., Worsnop, Douglas R., Baltensperger, Urs, Kulmala, Markku, Carslaw, Kenneth S., Curtius, Joachim
Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood1. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours2. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere3,4, and that ions have a relatively minor role5. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded6,7. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of α-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.
Experimental particle formation rates spanning tropospheric sulfuric acid and ammonia abundances, ion production rates, and temperatures
2016, Kürten, Andreas, Bianchi, Federico, Almeida, Joao, Kupiainen-Määttä, Oona, Dunne, Eimear M., Duplissy, Jonathan, Williamson, Christina, Barmet, Peter, Breitenlechner, Martin, Dommen, Josef, Donahue, Neil M., Flagan, Richard C., Franchin, Alessandro, Gordon, Hamish, Hakala, Jani, Hansel, Armin, Heinritzi, Martin, Ickes, Luisa, Jokinen, Tuija, Kangasluoma, Juha, Kim, Jaeseok, Kirkby, Jasper, Kupc, Agnieszka, Lehtipalo, Katrianne, Leiminger, Markus, Makhmutov, Vladimir, Onnela, Antti, Ortega, Ismael K., Petäjä, Tuukka, Praplan, Arnaud P., Riccobono, Francesco, Rissanen, Matti P., Rondo, Linda, Schnitzhofer, Ralf, Schobesberger, Siegfried, Smith, James N., Steiner, Gerhard, Stozhkov, Yuri, Tomé, António, Tröstl, Jasmin, Tsagkogeorgas, Georgios, Wagner, Paul E., Wimmer, Daniela, Ye, Penglin, Baltensperger, Urs, Carslaw, Ken, Kulmala, Markku, Curtius, Joachim
Binary nucleation of sulfuric acid and water as well as ternary nucleation involving ammonia are thought to be the dominant processes responsible for new particle formation (NPF) in the cold temperatures of the middle and upper troposphere. Ions are also thought to be important for particle nucleation in these regions. However, global models presently lack experimentally measured NPF rates under controlled laboratory conditions and so at present must rely on theoretical or empirical parameterizations. Here with data obtained in the European Organization for Nuclear Research CLOUD (Cosmics Leaving OUtdoor Droplets) chamber, we present the first experimental survey of NPF rates spanning free tropospheric conditions. The conditions during nucleation cover a temperature range from 208 to 298 K, sulfuric acid concentrations between 5 × 105 and 1 × 109 cm−3, and ammonia mixing ratios from zero added ammonia, i.e., nominally pure binary, to a maximum of ~1400 parts per trillion by volume (pptv). We performed nucleation studies under pure neutral conditions with zero ions being present in the chamber and at ionization rates of up to 75 ion pairs cm−3 s−1 to study neutral and ion-induced nucleation. We found that the contribution from ion-induced nucleation is small at temperatures between 208 and 248 K when ammonia is present at several pptv or higher. However, the presence of charges significantly enhances the nucleation rates, especially at 248 K with zero added ammonia, and for higher temperatures independent of NH3 levels. We compare these experimental data with calculated cluster formation rates from the Atmospheric Cluster Dynamics Code with cluster evaporation rates obtained from quantum chemistry.
The effect of acid-base clustering and ions on the growth of atmospheric nano-particles
2016, Lehtipalo, Katrianne, Rondo, Linda, Kontkanen, Jenni, Schobesberger, Siegfried, Jokinen, Tuija, Sarnela, Nina, Kürten, Andreas, Ehrhart, Sebastian, Franchin, Alessandro, Nieminen, Tuomo, Kulmala, Markku, Riccobono, Francesco, Sipila, Mikko, Yli-Juuti, Taina, Duplissy, Jonathan, Adamov, Alexey, Ahlm, Lars, Almeida, Joa˜o, Amorim, Antonio, Bianchi, Federico, Breitenlechner, Martin, Dommen, Josef, Downard, Andrew J., Dunne, Eimear M., Flagan, Richard C., Guida, Roberto, Hakala, Jani, Hansel, Armin, Jud, Werner, Kangasluoma, Juha, Kerminen, Veli-Matti, Keskinen, Helmi, Kim, Jaeseok, Kirkby, Jasper, Kupc, Agnieszka, Kupiainen-Määttä, Oona, Laaksonen, Ari, Lawler, Michael J., Leiminger, Markus, Mathot, Serge, Olenius, Tinja, Ortega, Ismael K., Onnela, Antti, Petäjä, Tuukka, Praplan, Arnaud, Rissanen, Matti P., Ruuskanen, Taina, Santos, Filipe D., Schallhart, Simon, Schnitzhofer, Ralf, Simon, Mario, Smith, James N., Tröstl, Jasmin, Tsagkogeorgas, Georgios, Tomé, António, Vaattovaara, Petri, Vehkamäki, Hanna, Vrtala, Aron E., Wagner, Paul E., Williamson, Christina, Wimmer, Daniela, Winkler, Paul M., Virtanen, Annele, Donahue, Neil M., Carslaw, Kenneth S., Baltensperger, Urs, Riipinen, Ilona, Curtius, Joachim, Worsnop, Douglas R., Kulmala, Markku
The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted for in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. We bring these observations into a coherent framework and discuss their significance in the atmosphere.