Benchmarking nitrogen deposition models

CERC are taking part in a model inter-comparison study led by RIVM in the Netherlands to benchmark local scale nitrogen deposition dispersion models. The project was motivated by the significant number of nitrogen deposition limit value exceedances in Dutch Natura 2000 areas and a 2019 High Court Ruling, which concluded that the current Dutch policy to reduce nitrogen deposition was inadequate. In response, the Dutch Ministry of Agriculture, Fisheries, Food Security and Nature initiated a research programme to propose and implement improvements in the Dutch measurement and modelling system that is used to evaluate the nitrogen deposition on nature areas. This model-intercomparison study for local scale is part of that research programme.

The study has two parts. Firstly, participating models have been set up to represent a wide range of source types and terrain, for example agricultural and traffic sources in mixed land use areas. Ten years of hourly and annual concentration and deposition values have been generated for each model configuration, and then inter-compared. The second stage of the project involves evaluation of model outputs using measurement data from a number of field campaigns. RIVM are currently finalizing the campaign datasets, and models will be set up and run over the summer.

The UK Centre for Ecology and Hydrology, VITO (Belgium), and Aarhaus University (Denmark) are also participating in the benchmarking study using Gaussian dispersion models. In addition, a group from the Dutch Wageningen University is running Large Eddy Simulations to inform the study outcomes. Results will be made public following project completion, which is scheduled for the end of 2024.

The Atmospheric Dispersion Modelling Liaison Committee (ADMLC), which has been supporting research into atmospheric dispersion modelling methods for over 25 years, has part-funded CERC`s participation in this project.