Filters

2012 - 20173

More filters

20193
Reset filters

Settings

End date: 2019 × Start date: 2016 × Type: article × Version: publishedVersion × Subject: aerosol × Subject: nucleation ×

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    How to find bananas in the atmospheric aerosol': New approach for analyzing atmospheric nucleation and growth events
    (Milton Park : Taylor & Francis, 2017) Heintzenberg, Jost; Wehner, Birgit; Birmili, Wolfram
    We have devised a new search algorithm for secondary particle formation events, or ‘nucleation events’ in data sets of atmospheric particle size distributions. The search algorithm is simple and based on the investigation of 18 integral parameters of the particle size distribution, three of which were found to be most relevant for identifying nucleation events. The algorithm is tested using long-term size distribution data sets of high-size resolution observed at Melpitz, Hohenpeissenberg, and Leipzig, Germany, and Beijing, China, thereby covering a wide range of clean and polluted conditions. By specifying the particular training sets, the method can be used by other researchers with different data sets or different research goals. The same search approach could be applied to identify and analyze other systematic changes in size distribution such as during frontal passages or sand storms. As an example application of the new algorithm, the 50 strongest nucleation events (‘bananas’) at each of the four sites are analyzed statistically in terms of average changes of integral parameters of the particle size distribution.
  • Thumbnail Image
    Item
    The atmospheric aerosol over Siberia, as seen from the 300 m ZOTTO tower
    (Milton Park : Taylor & Francis, 2017) Heintzenberg, Jost; Birmili, Wolfram; Theiss, Detlef; Kisilyakhov, Yegor
    This report describes a unique setup for aerosol measurements at the new long-term Tall Tower monitoring facility near Zotino, Siberia (ZOTTO). Through two inlets at 50 and 300 m aerosol particle number size distributions are measured since September 2006 in the size range 15–835 nanometer dry diameter. Until the end of May 2007 total number (N300) concentrations at 300 m height ranged between 400 cm-3 (5%) and 4000 cm-3 (95%) with a median of 1200 cm-3, which is rather high for a nearly uninhabited boreal forest region during the low productivity period of the year. Fitting 1-h average distributions with a maximum of four lognormal functions yielded frequent ultrafine modes below 20 nm at 50 m height than at 300 m, whereas the latter height more frequently showed an aged nucleation mode near 30 nm. The positions of Aitken (≈80 nm) and accumulation modes (≈210 nm) were very similar at both inlet heights, the very sharp latter one being the most frequent of all modes. The encouraging first results let us expect exciting newfindings during the summer period with frequent forest fires and secondary particle sources from vegetation emissions.
  • Thumbnail Image
    Item
    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.