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Author: Kulmala, M. × End date: 2019 × Start date: 2019 × Start date: 1984 × Type: Text × Publisher: München : European Geopyhsical Union × Subject: aerosol × Subject: nucleation × WGL Institute: TROPOS ×

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    Evolution of particle composition in CLOUD nucleation experiments
    (München : European Geopyhsical Union, 2013) Keskinen, H.; Virtanen, A.; Joutsensaari, J.; Tsagkogeorgas, G.; Duplissy, J.; Schobesberger, S.; Gysel, M.; Riccobono, F.; Slowik, J.G.; Bianchi, F.; Yli-Juuti, T.; Lehtipalo, K.; Rondo, L.; Breitenlechner, M.; Kupc, A.; Almeida, J.; Amorim, A.; Dunne, E.M.; Downard, A.J.; Ehrhart, S.; Franchin, A.; Kajos, M.K.; Kirkby, J.; Kürten, A.; Nieminen, T.; Makhmutov, V.; Mathot, S.; Miettinen, P.; Onnela, A.; Petäjä, T.; Praplan, A.; Santos, F.D.; Schallhart, S.; Sipilä, M.; Stozhkov, Y.; Tomé, A.; Vaattovaara, P.; Wimmer, D.; Prevot, A.; Dommen, J.; Donahue, N.M.; Flagan, R.C.; Weingartner, E.; Viisanen, Y.; Riipinen, I.; Hansel, A.; Curtius, J.; Kulmala, M.; Worsnop, D.R.; Baltensperger, U.; Wex, H.; Stratmann, F.; Laaksonen, A.
    Sulphuric acid, ammonia, amines, and oxidised organics play a crucial role in nanoparticle formation in the atmosphere. In this study, we investigate the composition of nucleated nanoparticles formed from these compounds in the CLOUD (Cosmics Leaving Outdoor Droplets) chamber experiments at CERN (Centre européen pour la recherche nucléaire). The investigation was carried out via analysis of the particle hygroscopicity, ethanol affinity, oxidation state, and ion composition. Hygroscopicity was studied by a hygroscopic tandem differential mobility analyser and a cloud condensation nuclei counter, ethanol affinity by an organic differential mobility analyser and particle oxidation level by a high-resolution time-of-flight aerosol mass spectrometer. The ion composition was studied by an atmospheric pressure interface time-of-flight mass spectrometer. The volume fraction of the organics in the particles during their growth from sizes of a few nanometers to tens of nanometers was derived from measured hygroscopicity assuming the Zdanovskii–Stokes–Robinson relationship, and compared to values gained from the spectrometers. The ZSR-relationship was also applied to obtain the measured ethanol affinities during the particle growth, which were used to derive the volume fractions of sulphuric acid and the other inorganics (e.g. ammonium salts). In the presence of sulphuric acid and ammonia, particles with a mobility diameter of 150 nm were chemically neutralised to ammonium sulphate. In the presence of oxidation products of pinanediol, the organic volume fraction of freshly nucleated particles increased from 0.4 to ~0.9, with an increase in diameter from 2 to 63 nm. Conversely, the sulphuric acid volume fraction decreased from 0.6 to 0.1 when the particle diameter increased from 2 to 50 nm. The results provide information on the composition of nucleated aerosol particles during their growth in the presence of various combinations of sulphuric acid, ammonia, dimethylamine and organic oxidation products.
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    The regional aerosol-climate model REMO-HAM
    (München : European Geopyhsical Union, 2012) Pietikäinen, J.-P.; O'Donnell, D.; Teichmann, C.; Karstens, U.; Pfeifer, S.; Kazil, J.; Podzun, R.; Fiedler, S.; Kokkola, H.; Birmili, W.; O'Dowd, C.; Baltensperger, U.; Weingartner, E.; Gehrig, R.; Spindler, G.; Kulmala, M.; Feichter, J.; Jacob, D.; Laaksonen, A.
    REMO-HAM is a new regional aerosol-climate model. It is based on the REMO regional climate model and includes most of the major aerosol processes. The structure for aerosol is similar to the global aerosol-climate model ECHAM5-HAM, for example the aerosol module HAM is coupled with a two-moment stratiform cloud scheme. On the other hand, REMO-HAM does not include an online coupled aerosol-radiation nor a secondary organic aerosol module. In this work, we evaluate the model and compare the results against ECHAM5-HAM and measurements. Four different measurement sites were chosen for the comparison of total number concentrations, size distributions and gas phase sulfur dioxide concentrations: Hyytiälä in Finland, Melpitz in Germany, Mace Head in Ireland and Jungfraujoch in Switzerland. REMO-HAM is run with two different resolutions: 50 × 50 km2 and 10 × 10 km2. Based on our simulations, REMO-HAM is in reasonable agreement with the measured values. The differences in the total number concentrations between REMO-HAM and ECHAM5-HAM can be mainly explained by the difference in the nucleation mode. Since we did not use activation nor kinetic nucleation for the boundary layer, the total number concentrations are somewhat underestimated. From the meteorological point of view, REMO-HAM represents the precipitation fields and 2 m temperature profile very well compared to measurement. Overall, we show that REMO-HAM is a functional aerosol-climate model, which will be used in further studies.