Emissions of biogenic trace gases from soils and plants often show strong spatial and temporal variation. Thus, there is a need for the development of area-integrating measurement techniques with good time resolution. The present paper describes area-integrated measurements of ammonia emissions after spreading of pig slurry on a wheat field, based on flux-gradient measurements using Fourier transform infrared (FTIR) spectroscopy. Two methods are described; the aerodynamic method where the flux is derived from measured micrometeorological parameters, and a tracer method where the flux is derived from simultaneous measurements of a tracer gas released over the area under study. Although not ideal in the actual measurement situation, this latter method has a potential for use on more local sources with less restrictions on micrometeorological conditions, and is thus included for validation. A code for modelling of the "footprint" of gradient measurements is also described, and is used to compare the results from the above-mentioned methods. (C) 2000 Elsevier Science Ltd. All rights reserved.
Galle, B., Klemedtsson, L., Bergqvist, B., Ferm, M., Törnqvist, K., Griffith, D. W. T., Jensen, N-O., & Hansen, F. (2000). Measurements of ammonia emissions from spreading of manure using gradient FTIR techniques. Atmospheric Environment, 34(28), 4907-4915. https://doi.org/10.1016/S1352-2310(00)00220-X