Estimation of Ammonia Flux Over A Semi-natural Grassland Based On Profile Measurements

Ammonia flux measurements have been started at the end of December, 1999 over a semi-natural grassland. The concentration profile of ammonia was determined by a three-channel AMANDA denuder system. The inlets of AMANDA were settled at 50, 100 and 200 cm heights above the grass. The duration of one cycle of measurement (3 levels) was 7.5 minutes. Half an hour averages were used to calculate the ammo- nia flux. Around 100 measurement day records have been collected during the years of 2000 and 2001. Turbulent flux of ammonia was determined by profile method. Meteorological parameters were simultaneously measured using a sonic anemome- ter, and a Bowen-ratio system. Data were collected using 30 minute averaging time. Momentum-, sensible-, latent- and soil heat fluxes were also calculated from the mea- surements. An extensive analysis of dataset, such as ammonia exchange between the semi-natural grassland and the near surface layer during different meteorological con- ditions are presented in this study. Effects of various natural and anthropogenic sources (volatilization from livestock wastes, fertilization) on ammonia flux are also analysed.