Auflistung nach Autor:in "Zikova, Nadezda"

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Number size distributions and seasonality of submicron particles in Europe 2008–2009
(Copernicus, 15.06.2011) Asmi, Ari; Wiedensohler, Alfred; Laj, Paolo; Fjaeraa, Ann Mari; Sellegri, Karine; Birmili, Wolfram; Weingartner, Ernest; Baltensperger, Urs; Zdimal, Vladimir; Zikova, Nadezda; Putaud, Jean-Philippe; Marinoni, Angela; Tunved, Peter; Hansson, Hans-Christen; Fiebig, Markus; Kivekäs, Niku; Lihavainen, Heikki; Asmi, Eija; Ulevicius, Vidmantas; Aalto, Pasi Pekka; Swietlicki, Erik; Kristensson, Adam; Mihalopoulos, Nikolaos; Kalivitis, Nikos; Kalapov, Ivo; Kiss, Gyula; de Leeuw, Gerrit; Henzing, Bas; Harrison, Roy; Beddows, David; O'Dowd, Colin; Jennings, Stephen G.; Flentje, Harald; Weinhold, Kay; Meinhardt, Frank; Ries, Ludwig; Kulmala, Markku
Two years of harmonized aerosol number size distribution data from 24 European field monitoring sites have been analysed. The results give a comprehensive overview of the European near surface aerosol particle number concentrations and number size distributions between 30 and 500 nm of dry particle diameter. Spatial and temporal distribution of aerosols in the particle sizes most important for climate applications are presented. We also analyse the annual, weekly and diurnal cycles of the aerosol number concentrations, provide log-normal fitting parameters for median number size distributions, and give guidance notes for data users. Emphasis is placed on the usability of results within the aerosol modelling community. We also show that the aerosol number concentrations of Aitken and accumulation mode particles (with 100 nm dry diameter as a cut-off between modes) are related, although there is significant variation in the ratios of the modal number concentrations. Different aerosol and station types are distinguished from this data and this methodology has potential for further categorization of stations aerosol number size distribution types. The European submicron aerosol was divided into characteristic types: Central European aerosol, characterized by single mode median size distributions, unimodal number concentration histograms and low variability in CCN-sized aerosol number concentrations; Nordic aerosol with low number concentrations, although showing pronounced seasonal variation of especially Aitken mode particles; Mountain sites (altitude over 1000 m a.s.l.) with a strong seasonal cycle in aerosol number concentrations, high variability, and very low median number concentrations. Southern and Western European regions had fewer stations, which decreases the regional coverage of these results. Aerosol number concentrations over the Britain and Ireland had very high variance and there are indications of mixed air masses from several source regions; the Mediterranean aerosol exhibit high seasonality, and a strong accumulation mode in the summer. The greatest concentrations were observed at the Ispra station in Northern Italy with high accumulation mode number concentrations in the winter. The aerosol number concentrations at the Arctic station Zeppelin in Ny-Ålesund in Svalbard have also a strong seasonal cycle, with greater concentrations of accumulation mode particles in winter, and dominating summer Aitken mode indicating more recently formed particles. Observed particles did not show any statistically significant regional work-week or weekday related variation in number concentrations studied. Analysis products are made for open-access to the research community, available in a freely accessible internet site. The results give to the modelling community a reliable, easy-to-use and freely available comparison dataset of aerosol size distributions.
01A - Beitrag in wissenschaftlicher Zeitschrift
Variations in tropospheric submicron particle size distributions across the European continent 2008–2009
(Copernicus, 2014) Beddows, David; Dall'Osto, Manuel; Harrison, Roy; Kulmala, Markku; Asmi, Ari; Wiedensohler, Alfred; Laj, Paolo; Fjaeraa, Ann Mari; Sellegri, Karine; Birmili, Wolfram; Bukowiecki, Nicolas; Weingartner, Ernest; Baltensperger, Urs; Zdimal, Vladimir; Zikova, Nadezda; Putaud, Jean-Philippe; Marinoni, Angela; Tunved, Peter; Hansson, Hans-Christen; Fiebig, Markus; Kivekäs, Niku; Swietlicki, Erik; Lihavainen, Heikki; Asmi, Eija; Ulevicius, Vidmantas; Aalto, Pasi Pekka; Mihalopoulos, Nikolaos; Kalivitis, Nikos; Kalapov, Ivo; Kiss, Gyula; de Leeuw, Gerrit; Henzing, Bas; O'Dowd, Colin; Jennings, Stephen G.; Flentje, Harald; Meinhardt, Frank; Ries, Ludwig; Denier van der Gon, Hugo; Visschedijk, Antoon
Cluster~analysis of particle number size distributions from~background sites across Europe~is presented. This generated a total of nine clusters of particle size distributions which could be further combined into two main groups, namely: a south-to-north category (four clusters) and a west-to-east category (five clusters). The first group was identified as most frequently being detected inside and around northern Germany and neighbouring countries, showing clear evidence of local afternoon nucleation and growth events that could be linked to movement of air masses from south to north arriving ultimately at the Arctic contributing to Arctic haze.~The second group of particle size spectra proved to have narrower size distributions and collectively showed a dependence of modal diameter upon the longitude of the site (west to east) at which they were most frequently detected.~These clusters indicated regional nucleation (at the coastal sites) growing to larger modes further inland. The apparent growth rate of the modal diameter was around 0.6–0.9 nm h−1. Four specific air mass back-trajectories were successively taken as case studies to examine in real time the evolution of aerosol size distributions across Europe. ~While aerosol growth processes can be observed as aerosol traverses Europe, the processes are often obscured by the addition of aerosol by emissions en route. This study revealed that some of the 24 stations exhibit more complex behaviour than others, especially when impacted by local sources or a variety of different air masses. Overall, the aerosol size distribution clustering analysis greatly simplifies the complex data set and allows a description of aerosol aging processes, which reflects the longer-term average development of particle number size distributions as air masses advect across Europe.
01A - Beitrag in wissenschaftlicher Zeitschrift