A one-week field measurement campaign has been carried out on a winter wheat field nearby a cattle farm in Poland. The aim of the campaign was to demonstrate applicability of a recently developed photoacoustic ammonia monitoring instrument for environmental research purposes. The photoacoustic instrument was operated with three sampling lines, and a wet-chemical AMANDA instrument with one sampling inlet was used as a reference for ammonia concentration monitoring. In addition to the ammonia measurements, several meteorological parameters were measured with a micrometeorological station. The campaign was started with instrument intercomparison when all inlets of the ammonia monitoring instruments were placed at the same point. Good agreement has been found between concentration data measured by the three channels of the photoacoustic instrument and the AMANDA, which proves reliability of the instruments. In the second part of the campaign, plume detection and flux measurement were carried out. During this period the photoacoustic instrument was placed 130 m east, the AMANDA instrument was placed 46 m northeast from the farm; and the photoacoustic instrument operated in gradient configuration, i.e., with the three sampling inlets placed at three different heights above canopy level. Background concentration was found to be around 2 μgm-3, which is typical for agricultural landscapes. Concentrations up to 60 μgm-3 were observed in case of wind blowing from the direction of the farm, and difference between concentrations measured at the two different locations around the farm varied according to wind direction, indicating changing position of the ammonia plume around the farm. Concentration gradients measured by the photoacoustic instrument during the campaign showed strong diurnal variation according to atmospheric stability. Ammonia fluxes calculated from the measured gradients were in the range of 0 to -90 ng m-2 s-1, in good agreement with expectations.
|Number of pages||15|
|Publication status||Published - Jan 10 2012|
- Photoacoustic spectroscopy
- Plume detection
- Surface-atmosphere exchange flux
ASJC Scopus subject areas
- Atmospheric Science