Studying the City Plume of Berlin on 20 July 1998 with Three Different Modelling Approaches |
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| Authors: | Andreas Becker Bernhard Scherer Michael Memmesheimer Heiner Geiß |
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| Institution: | (1) Chair for Environmental Meteorology, Brandenburg University of Technology Cottbus, Haus 215, Burger Chaussee 2, D-03044 Cottbus, Germany;(2) Present address: Comprehensive Nuclear Test Ban Treaty Organisation (PTS/PrepCom/CTBTO), Vienna International Centre, P.O. Box 1200, A-1400 Vienna, Austria;(3) Institute for Meterology, Free University of Berlin, Carl-Heinrich Becker-Weg 6-10, D-12165 Berlin, Germany;(4) Institute for Geophysics and Meteorology, EURAD Project, University of Cologne, Aachener Str. 201–209, D-50923 Cologne, Germany;(5) Institut für Chemie der Belasteten Atmosphäre, Forschungszentrum Jülich GmbH, PO Box 1913, D-52425 Jülich, Germany |
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| Abstract: | In this paper we try to identify and describe the specifics of the Berlin city plume characterised by a zone of enhanced photochemical activity downwind of the urban area, where the major emissions of ozone precursors (NOx and VOC) take place. Two Eulerian CTM systems (EURAD and REM3/CALGRID) and one Euler–Lagrangian model (LaMM5) are applied to thearea of Berlin/Brandenburg to investigate the processes involved in the evolution of the Berlin plume inherent to the models. The study focuses on 20 July 1998,the first special observation period (SOP) during BERLIOZ. The examination includes (1) the role of turbulence and transport and the role of mass flux to the surface during the evolution of the plume, (2) the import situation of the ground based measurement sites, (3)the terms of the ozone budget equation and their contribution to precursor distribution and ozone formation, (4) the substructures of the plume defined by its chemical regimes. Main results show that the complex meteorological conditions during this SOP with considerable turbulent transports demand an Euler–Lagrangian approach to determine the source receptor relationshipsfor the ground based measurement sites. These relations reveal that only a minor part ( 5%) of the air approaching Pabstthum and the more downwind (north-western) stations origins from Berlin and that the mutual transport between all sites was limited. The latter result afflicts the joint interpretation of data from different stations because the presumption to measure the same air mass is violated in many cases for this SOP. The CTM results reveal that the local net production of ozone within the plume was controlled by transport ad chemical processes both owning the same importance but tending to counteract each other. At this SOP far distance sources of ozone precursors originating from the Bohemian basin did not interfere the Berlin city plume although they generally have the potential to do so. |
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| Keywords: | ozone episode urban plume source-receptor relationships chemistry-transport modelling BERLIOZ experiment |
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