Trend Analysis of Air Pollution and Nitrogen Deposition Over the Netherlands Using the EMEP4NL and OPS Model

A trend analysis is performed over the period 2006–2015 for concentration and deposition of nitrogen compounds over the Netherlands. The analysis is performed with high resolution (~1 km) model simulations with the Gaussian plume model OPS and the grid model EMEP4NL. Both models use the same MACC III emission distribution for countries outside of the Netherlands, and spatially more detailed emissions for the Netherlands itself. Emission totals per SNAP sector per country are used over the period 2006–2015, according to the latest CEIP expert estimates. The OPS model is driven with yearly specific meteorological fields provided by the Royal Netherlands Meteorological Institute (KNMI), while EMEP4NL is driven by meteorological output data from the open source WRF meteorological model. Results from the model calculations are first compared with measurements. Next, the focus of the analysis will be on the effect of atmospheric chemistry on trend analysis of nitrogen components, like ammonia and ammonium in the atmosphere, and the dry and wet nitrogen deposition to the surface: OPS strongly parameterizes the chemistry, whereas EMEP4NL uses a state-of-the-art chemistry scheme. The influence of atmospheric chemistry on modeled trends in concentration and deposition is determined by comparing the trend calculations of both models, and their connection with trends in emissions of precursor gases over the period 2006–2015.