Validation of nitrogen dry deposition modelling above forest using high-frequency flux measurements

Atmospheric deposition of reactive N compounds influences the productivity of natural ecosystems and its carbon dioxide exchange. As increasing N deposition may become harmful for a variety of ecosystems, it is necessary to thoroughly estimate the nitrogen exchange between biosphere and atmosphere. Measurements of ΣNr were carried out with a custom-built converter coupled to a chemiluminescene detector (CLD). The Total Reactive Atmospheric Nitrogen Converter (TRANC) (Marx et al., 2012) was used to convert all reactive nitrogen compounds (ΣNr), except for nitrous oxide (N2O) and molecular nitrogen (N2), to nitrogen oxide (NO). Fluxes were determined with the EC method and used to validate deposition routines.

The measurements took place in the Bavarian Forest National Park at a natural mixed-forest site away from agricultural and industrial emission hotspots to determine background ∑Nr deposition in the absence of anthropogenic sources. The measurement period was from January 2016 until June 2018.