Use of the ACDEP trajectory model in the Danish nation-wide Background Monitoring Programme

The frequently observed eutrophication problems in Danish marine waters are associated with high nutrient loads. This paper outlines how the atmospheric part of the load is determined within the framework of the Danish Background Monitoring Programme. The analyses within the programme are carried out by use of both measurements and model calculations, where the modelling part receives the main focus in this paper. The performed calculations indicate that the atmospheric nitrogen deposition to the Danish marine waters is of comparable size to the river run-off, and in some periods even the dominating contribution to the overall nitrogen input. The model results are shown to be sensitive to the resolution of the meteorological input data for the calculations. Strong improvement of the model performance is the result when meteorological data with much higher temporal and spatial resolution are applied.