•Wolfgang Grabmer¹, Martin Graus¹, Christian Lindinger¹, Armin Wisthaler¹, Armin Hansel¹, Bernhard Rappenglueck², Dominik Steigner², Roos Zuurbier² und Rainer Steinbrecher^2
2Institut fuer Meteorologie und Klimaforschung, Atmosphaerische Umweltforschung, FZ Karlsruhe, Garmisch-Partenkirchen
¹Institut fuer Ionenphysik, Universitaet Innsbruck

A disjunct eddy covariance (DEC) measurement system, which determines the fluxes of biogenic volatile organic compounds (BVOCs) out of vegetation, has been tested in the field. In disjunct sampling, short separate samples are taken instead of continuously sampling the air as in traditional relaxed eddy accumulation (REA) and true eddy covariance systems. This method reduces the number of samples but allows more time to analyse them in order to gain higher measurement precision and accuracy. The disjunct eddy covariance system combined with PTR-MS analysis (proton transfer reaction mass spectrometry) was successfully deployed to measure monoterpene fluxes during the BEWA field campaign 2002 at the Waldstein tower in the Bavarian Fichtelgebirge. The ability of the system to measure monoterpene fluxes above a Norway Spruce (Picea abies) forest was demonstrated by comparing successfully flux results obtained with the REA and enclosure approach at the same location.