Atmospheric Chemistry and Physics

Abstract. The nitrogen dioxide (NO2) exchange between the atmosphere and needles of Picea abies L. (Norway Spruce) was studied under uncontrolled field conditions using a dy-namic chamber system. This system allows measurements of the flux density of the reactive NO-NO2-O3 triad and additionally of the non-reactive trace gases CO2 and H2O. For the NO2 detection a highly NO2 specific blue light converter was used, which was coupled to chemilumines-cence detection of the photolysis product NO. This NO2 converter excludes known interferences with other nitrogen compounds, which occur by using more unspecific NO2 con-verters. Photo-chemical reactions of NO, NO2, and O3 in-side the dynamic chamber were considered for the determi-nation of NO2 flux densities, NO2 deposition velocities, as well as NO2 compensation point concentrations. The cal