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Successful calculation of human and natural influence on cloud formation

CLOUD data are fed into a global aerosol model to calculate climate effects.

Date:
November 4, 2016
Source:
Goethe-Universität Frankfurt am Main
Summary:
When new particles develop in the atmosphere, this influences cloud formation and with that the climate too. Since a few years, these complex processes have been reproduced in a large air chamber within the CLOUD experiment at CERN. Researchers have now used the results for the first time to calculate the production of aerosol particles in all the Earth's regions and at different heights. The study deciphers the role of the various chemical systems which are responsible for particle formation. They also determined the influence of ions which develop through cosmic radiation.
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When new particles develop in the atmosphere, this influences cloud formation and with that the climate too. Since a few years, these complex processes have been reproduced in a large air chamber within the CLOUD experiment at CERN. Researchers have now used the results for the first time to calculate the production of aerosol particles in all the Earth's regions and at different heights. The study published in the journal "Science," in which researchers from Goethe University Frankfurt were involved, deciphers the role of the various chemical systems which are responsible for particle formation. They also determined the influence of ions which develop through cosmic radiation.

Soot particles, dust lifted up by the wind or sea spray account for only some of the particles in the atmosphere. Others develop from certain trace vapours, for example when individual sulphuric acid and water molecules cluster as tiny droplets. This formation of new particles is known as nucleation. Clouds are formed by water condensing on the larger aerosol particles or what are known as cloud condensation nuclei. The more cloud droplets develop, the more sunlight is reflected back into space. Climate models show that the additional particles caused by human activity produce a cooling effect which partially offsets the greenhouse effect. It is, however, less than previously assumed.

Aerosol particles from sulphuric acid and ammonia emissions

The model calculations presented in "Science" prove that about half the cloud condensation nuclei in the atmosphere originate from nucleation. In the atmosphere today, particle formation is dominated almost everywhere by mechanisms where at least three chemical components must come together: apart from the two basic substances, i.e. sulphuric acid and water, these are either ammonia or specific organic compounds such as oxidation products from terpenes. Close to ground level, organic substances from natural sources are important, whilst ammonia plays a key role higher up in the troposphere. Ammonia and sulphur emissions have increased considerably over the past decades as a result of human activities.

11-year solar cycle has scarcely any influence

CLOUD has also investigated how the 11-year solar cycle influences the formation of aerosol particles in our present-day atmosphere. The model calculations show that the effects as a result of changes in ionisation through the sun are too small to make a significant contribution to cloud formation. Although the ions are originally involved in the development of almost one third of all newly formed particles, the concentration of the large cloud condensation nuclei in the course of the 11-year cycle changes by only 0.1 percent -- not enough to have any sizeable influence on the climate.

Cooling effects 27 percent less than expected

The CLOUD team has also presented first global model calculations for aerosol formation caused without the involvement of sulphuric acid and solely through extremely low volatile substances of biological origin (Gordon et al., PNAS). According to the findings, this process contributed significantly to particle formation above all in the pre-industrial atmosphere, since at that time far less sulphur components were released into the atmosphere. The number of particles in the pre-industrial atmosphere is now estimated to be far greater through the additional process than was shown in earlier calculations. The model calculations, which are based on data from the CLOUD experiment, reveal that the cooling effects of clouds are 27 percent less than in climate simulations without this effect as a result of additional particles caused by human activity: Instead of a radiative effect of -0.82 W/m2 the outcome is only -0.60 W/m2.


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Materials provided by Goethe-Universität Frankfurt am Main. Note: Content may be edited for style and length.


Journal References:

  1. E. M. Dunne, H. Gordon, A. Kurten, J. Almeida, J. Duplissy, C. Williamson, I. K. Ortega, K. J. Pringle, A. Adamov, U. Baltensperger, P. Barmet, F. Benduhn, F. Bianchi, M. Breitenlechner, A. Clarke, J. Curtius, J. Dommen, N. M. Donahue, S. Ehrhart, R. C. Flagan, A. Franchin, R. Guida, J. Hakala, A. Hansel, M. Heinritzi, T. Jokinen, J. Kangasluoma, J. Kirkby, M. Kulmala, A. Kupc, M. J. Lawler, K. Lehtipalo, V. Makhmutov, G. Mann, S. Mathot, J. Merikanto, P. Miettinen, A. Nenes, A. Onnela, A. Rap, C. L. S. Reddington, F. Riccobono, N. A. D. Richards, M. P. Rissanen, L. Rondo, N. Sarnela, S. Schobesberger, K. Sengupta, M. Simon, M. Sipila, J. N. Smith, Y. Stozkhov, A. Tome, J. Trostl, P. E. Wagner, D. Wimmer, P. M. Winkler, D. R. Worsnop, K. S. Carslaw. Global atmospheric particle formation from CERN CLOUD measurements. Science, 2016; DOI: 10.1126/science.aaf2649
  2. Hamish Gordon, Kamalika Sengupta, Alexandru Rap, Jonathan Duplissy, Carla Frege, Christina Williamson, Martin Heinritzi, Mario Simon, Chao Yan, João Almeida, Jasmin Tröstl, Tuomo Nieminen, Ismael K. Ortega, Robert Wagner, Eimear M. Dunne, Alexey Adamov, Antonio Amorim, Anne-Kathrin Bernhammer, Federico Bianchi, Martin Breitenlechner, Sophia Brilke, Xuemeng Chen, Jill S. Craven, Antonio Dias, Sebastian Ehrhart, Lukas Fischer, Richard C. Flagan, Alessandro Franchin, Claudia Fuchs, Roberto Guida, Jani Hakala, Christopher R. Hoyle, Tuija Jokinen, Heikki Junninen, Juha Kangasluoma, Jaeseok Kim, Jasper Kirkby, Manuel Krapf, Andreas Kürten, Ari Laaksonen, Katrianne Lehtipalo, Vladimir Makhmutov, Serge Mathot, Ugo Molteni, Sarah A. Monks, Antti Onnela, Otso Peräkylä, Felix Piel, Tuukka Petäjä, Arnaud P. Praplan, Kirsty J. Pringle, Nigel A. D. Richards, Matti P. Rissanen, Linda Rondo, Nina Sarnela, Siegfried Schobesberger, Catherine E. Scott, John H. Seinfeld, Sangeeta Sharma, Mikko Sipilä, Gerhard Steiner, Yuri Stozhkov, Frank Stratmann, Antonio Tomé, Annele Virtanen, Alexander Lucas Vogel, Andrea C. Wagner, Paul E. Wagner, Ernest Weingartner, Daniela Wimmer, Paul M. Winkler, Penglin Ye, Xuan Zhang, Armin Hansel, Josef Dommen, Neil M. Donahue, Douglas R. Worsnop, Urs Baltensperger, Markku Kulmala, Joachim Curtius, Kenneth S. Carslaw. Reduced anthropogenic aerosol radiative forcing caused by biogenic new particle formation. Proceedings of the National Academy of Sciences, 2016; 113 (43): 12053 DOI: 10.1073/pnas.1602360113

Cite This Page:

Goethe-Universität Frankfurt am Main. "Successful calculation of human and natural influence on cloud formation: CLOUD data are fed into a global aerosol model to calculate climate effects.." ScienceDaily. ScienceDaily, 4 November 2016. <www.sciencedaily.com/releases/2016/11/161104101855.htm>.
Goethe-Universität Frankfurt am Main. (2016, November 4). Successful calculation of human and natural influence on cloud formation: CLOUD data are fed into a global aerosol model to calculate climate effects.. ScienceDaily. Retrieved May 26, 2017 from www.sciencedaily.com/releases/2016/11/161104101855.htm
Goethe-Universität Frankfurt am Main. "Successful calculation of human and natural influence on cloud formation: CLOUD data are fed into a global aerosol model to calculate climate effects.." ScienceDaily. www.sciencedaily.com/releases/2016/11/161104101855.htm (accessed May 26, 2017).

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