摘要： From April 11th to May 27th, 2011, the turbulent exchange of sub-micrometer particles between the urban surface and the urban boundary-layer was measured above the city area of Münster (NW Germany). The scope of the study is to examine the contributions of particles of different size classes to the total measured fluxes. Eddy-covariance measurements were performed at 65 m above ground. The particle concentrations in 99 size bins with particle diameters ranging from 55 to 1000 nm were measured with an optical particle spectrometer. For flux calculations we grouped these 99 original bins into 18 wider channels with an upper cut-off of 320 nm, and a further rather coarse channel for particles up to 1 ?m. The overall results reveal that Münster is a relevant source of about 2.8 · 108 particles m?2 d?1 on weekdays and 1.8 · 108 particles m?2 d?1 on Sundays within the indicated size range. These emissions are predominantly driven by secondary particles of the Aitken mode, which are most likely caused by traffic. Hence traffic hotspots are a major contribution to the net fluxes. On the other hand, considering the mass fluxes, Münster is a sink of 0.53 ?g m?2 d?1 on weekdays and 0.08 ?g m?2 d?1 on Sundays. Here, mainly particles of the accumulation mode with diameters above 167 nm lead to deposition fluxes. Number and mass fluxes exhibit distinct daily and weekly patterns. 其他題名： Contributions to Atmospheric Sciences 出版者： Stuttgart: Borntraeger 出版日期： 2013-12-01 出處： Meteorologische Zeitschrift (Berlin, Germany : 1992), 2013-12, Vol.22 (6), p.729-737 資源來源： Directory of Open Access Journals - DOAJ (NTUSG) 版權： 2015 INIST-CNRS 識別號： ISSN: 0941-2948 識別號： ISSN: 1610-1227 識別號： EISSN: 1610-1227 識別號： DOI: 10.1127/0941-2948/2013/0441
