Abstract
Abstract. Interactions of reactive nitrogen (Nr) compounds between the atmosphere and the earth's surface play a key role in atmospheric chemistry and in understanding nutrient cycling of terrestrial ecosystems. While continuous observations of inert greenhouse gases through micrometeorological flux measurements have become a common procedure, information about temporal dynamics and longer-term budgets of Nr compounds is still extremely limited. Within the framework of the research projects NITROSPHERE and FORESTFLUX, field campaigns were carried out to investigate the biosphere–atmosphere exchange of selected Nr compounds over different land surfaces. The aim of the campaigns was to test and establish novel measurement techniques in eddy-covariance setups for continuous determination of surface fluxes of ammonia (NH3) and total reactive nitrogen (ΣNr) using two different analytical devices. While high-frequency measurements of NH3 were conducted with a quantum cascade laser (QCL) absorption spectrometer, a custom-built converter called Total Reactive Atmospheric Nitrogen Converter (TRANC) connected and operated upstream of a chemiluminescence detector (CLD) was used for the measurement of ΣNr. As high-resolution data of Nr surface–atmosphere exchange are still scarce but highly desired for testing and validating local inferential and larger-scale models, we provide access to campaign data including concentrations, fluxes, and ancillary measurements of meteorological parameters. Campaigns (n=4) were carried out in natural (forest) and semi-natural (peatland) ecosystem types. The published datasets stress the importance of recent advancements in laser spectrometry and help improve our understanding of the temporal variability of surface–atmosphere exchange in different ecosystems, thereby providing validation opportunities for inferential models simulating the exchange of reactive nitrogen. The dataset has been placed in the Zenodo repository (https://doi.org/10.5281/zenodo.4513854; Brümmer et al., 2022) and contains individual data files for each campaign.
Highlights
The term “reactive nitrogen” (Nr) describes all forms of nitrogen that are biologically, photochemically, and radiatively active
Our datasets demonstrate the suitability of quantum cascade laser (QCL) and TRANC (Total Reactive Atmospheric Nitrogen Converter) to measure eddy-covariance fluxes of NH3 and Nr, respectively
Practicality, and ease of operation, the standardization of field setups and data post-processing of reactive nitrogen measurements still have a highly experimental character, thereby being two decades behind those of inert greenhouse gas measurements, which are nowadays organized in continental-scale flux networks like ICOS in Europe (Heiskanen et al, 2022) or the National Ecological Observation Network (NEON, Metzger et al, 2019) in North America
Summary
The term “reactive nitrogen” (Nr) describes all forms of nitrogen that are biologically, photochemically, and radiatively active. Schrader et al, 2016) or within the framework of chemical transport models such as DEPAC (DEPosition of Acidifying Compounds) (Erisman et al, 1994) within LOTOS-EUROS (Long Term Ozone Simulation – European Operational Smog) (van Zanten et al, 2010; Manders et al, 2017) Outputs of these models help understand ecosystem functioning and can further be used for gap filling in order to compile total nitrogen budgets, which form the basis of national inventories of air pollutants and their assessment reports. We used a quantum cascade laser (QCL) absorption spectrometer and a custom-built converter called Total Reactive Atmospheric Nitrogen Converter (TRANC) connected upstream to a chemiluminescence detector (CLD) for measuring ammonia and total reactive nitrogen (hereafter named Nr) fluxes, respectively These datasets demonstrate the suitability of QCL and TRANC in eddy-covariance setups and – as in situ high-resolution data of surface–atmosphere fluxes of Nr compounds are still scarce – highlight potential applications such as model validation, understanding temporal dynamics. In the here presented study, we follow the nomenclature of Marx et al (2012), with the definition of Nr comprising all nitrogen-containing trace species but excluding N2 and N2O as these are non-reactive in the lower troposphere
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