Overview of the Berlin Plume Experiment (BERLIOZ Campaign in Summer 1998) and the German TFS Research Project

摘要

The Berlin Plume Experiment was a part of the German Tropospheric Research Program (TFS). It was integrated within Principal Subject 3 (LT-3): Process Studies on Formation of Oxidants and Oxidation Capacity. The work within principal subject 3 (LT-3) began on 01.08.1996 and ended on 30.06.1999 with the extension of some projects up to 30.04.2000. The aim of 3 LT-3 was the improvement of the model description of photosmog formation on the basis of an extended understanding of the processes which lead to the formation of photooxidants. Elevated concentrations of photooxidants over a certain threshold level are termed as photo-smog and occur when the precursor substances, volatile organic compounds (VOC including CO) and Nitrogen oxides (NO_x = NO_2 + NO) build up in the boundary layer during certain weather conditions. Sunlight irradiation of such air masses initiates photochemical primary steps which lead to radical chains, the oxidation of NO to NO_2 and eventually the formation of O_3 one of the major components of photosmog. Depending on the VOC/NO_x ratio and also the VOC composition it can come to either an acceleration of the ozone formation for to retardation by a NO_x and VOC excess, respectively. Besides the chemical reactions, horizontal and vertical transport processes also play a decisive role by the photosmog formation. This is true for ozone and also its precursors.