Auflistung nach Autor:in "Svenningsson, Birgitta"

Gerade angezeigt 1 - 3 von 3

A synthesis of cloud condensation nuclei counter (CCNC) measurements within the EUCAARI network
(Copernicus, 2015) Paramonov, Mikhail; Kerminen, Veli-Matti; Gysel, Martin; Aalto, Pasi Pekka; Andreae, Meinrat O.; Asmi, Eija; Baltensperger, Urs; Bougiatioti, Aikaterini; Brus, David; Frank, Göran; Good, Nicholas; Gunthe, Sachin S.; Hao, Liqing; Irwin, Martin; Jaatinen, Antti; Jurányi, Zsófia; King, S. M.; Kortelainen, Aki; Kristensson, Adam; Lihavainen, Heikki; Kulmala, Markku; Lohmann, Ulrike; Martin, Scot T.; McFiggans, Gordon; Mihalopoulos, Nikolaos; Nenes, Athanasios; O'Dowd, Colin D.; Ovadnevaite, Jurgita; Petäjä, Tuukka; Pöschl, Ulrich; Roberts, Greg; Rose, Diana; Svenningsson, Birgitta; Swietlicki, Erik; Weingartner, Ernest; Whitehead, James; Wiedensohler, Alfred; Wittbom, Cerina; Sierau, Berko
Cloud condensation nuclei counter (CCNC) measurements performed at 14 locations around the world within the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) framework have been analysed and discussed with respect to the cloud condensation nuclei (CCN) activation and hygroscopic properties of the atmospheric aerosol. The annual mean ratio of activated cloud condensation nuclei (NCCN) to the total number concentration of particles (NCN), known as the activated fraction A, shows a similar functional dependence on supersaturation S at many locations – exceptions to this being certain marine locations, a free troposphere site and background sites in south-west Germany and northern Finland. The use of total number concentration of particles above 50 and 100 nm diameter when calculating the activated fractions (A50 and A100, respectively) renders a much more stable dependence of A on S; A50 and A100 also reveal the effect of the size distribution on CCN activation. With respect to chemical composition, it was found that the hygroscopicity of aerosol particles as a function of size differs among locations. The hygroscopicity parameter κ decreased with an increasing size at a continental site in south-west Germany and fluctuated without any particular size dependence across the observed size range in the remote tropical North Atlantic and rural central Hungary. At all other locations κ increased with size. In fact, in Hyytiälä, Vavihill, Jungfraujoch and Pallas the difference in hygroscopicity between Aitken and accumulation mode aerosol was statistically significant at the 5 % significance level. In a boreal environment the assumption of a size-independent κ can lead to a potentially substantial overestimation of NCCN at S levels above 0.6 %. The same is true for other locations where κ was found to increase with size. While detailed information about aerosol hygroscopicity can significantly improve the prediction of NCCN, total aerosol number concentration and aerosol size distribution remain more important parameters. The seasonal and diurnal patterns of CCN activation and hygroscopic properties vary among three long-term locations, highlighting the spatial and temporal variability of potential aerosol–cloud interactions in various environments.
01A - Beitrag in wissenschaftlicher Zeitschrift
Hygroscopic properties of submicrometer atmospheric aerosol particles measured with H-TDMA instruments in various environments - a review
(Stockholm University Press, 01.01.2008) Swietlicki, Erik; Hansson, Hans-Christen; Hämeri, Kaarle; Svenningsson, Birgitta; Massling, Andreas; McFiggans, Gordon; McMurry, Peter H.; Petäjä, Tuukka; Tunved, Peter; Gysel, Martin; Topping, David; Weingartner, Ernest; Baltensperger, Urs; Rissler, Jenny; Wiedensohler, Alfred; Kulmala, Markku
The hygroscopic properties play a vital role for the direct and indirect effects of aerosols on climate, as well as the health effects of particulate matter (PM) by modifying the deposition pattern of inhaled particles in the humid human respiratory tract. Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA) instruments have been used in field campaigns in various environments globally over the last 25 yr to determine the water uptake on submicrometre particles at subsaturated conditions. These investigations have yielded valuable and comprehensive information regarding the particle hygroscopic properties of the atmospheric aerosol, including state of mixing. These properties determine the equilibrium particle size at ambient relative humidities and have successfully been used to calculate the activation of particles at water vapour supersaturation. This paper summarizes the existing published H-TDMA results on the sizeresolved submicrometre aerosol particle hygroscopic properties obtained from ground-based measurements at multiple marine, rural, urban and free tropospheric measurement sites. The data is classified into groups of hygroscopic growth indicating the external mixture, and providing clues to the sources and processes controlling the aerosol. An evaluation is given on how different chemical and physical properties affect the hygroscopic growth.
01A - Beitrag in wissenschaftlicher Zeitschrift
Subarctic atmospheric aerosol composition. 3. Measured and modeled properties of cloud condensation nuclei
(Wiley, 19.02.2010) Kammermann, Lukas; Gysel, Martin; Weingartner, Ernest; Herich, Hanna; Cziczo, Daniel J.; Holst, Thomas; Svenningsson, Birgitta; Arneth, Almut; Baltensperger, Urs
Aerosol particles can modify cloud properties by acting as cloud condensation nuclei (CCN). Predicting CCN properties is still a challenge and not properly incorporated in current climate models. Atmospheric particle number size distributions, hygroscopic growth factors, and polydisperse CCN number concentrations were measured at the remote subarctic Stordalen mire, 200 km north of the Arctic Circle in northern Sweden. The CCN number concentration was highly variable, largely driven by variations in the total number of sufficiently large particles, though the variability of chemical composition was increasingly important for decreasing supersaturation. The hygroscopicity of particles measured by a hygroscopicity tandem differential mobility analyzer (HTDMA) was in agreement with large critical diameters observed for CCN activation (κ ≈ 0.07–0.21 for D = 50–200 nm). Size distribution and time‐ and size‐resolved HTDMA data were used to predict CCN number concentrations. Agreement of predictions with measured CCN within ±11% was achieved using parameterized Köhler theory and assuming a surface tension of pure water. The sensitivity of CCN predictions to various simplifying assumptions was further explored: We found that (1) ignoring particle mixing state did not affect CCN predictions, (2) averaging the HTDMA data in time with retaining the size dependence did not introduce a substantial bias, while individual predictions became more uncertain, and (3) predictions involving the hygroscopicity parameter recommended in literature for continental sites (κ ≈ 0.3 ± 0.1) resulted in a significant prediction bias. Future modeling studies should therefore at least aim at using averaged, size‐resolved, site‐specific hygroscopicity or chemical composition data for predictions of CCN number concentrations.
01A - Beitrag in wissenschaftlicher Zeitschrift