Comparison of modelled and monitored deposition fluxes of sulphur and nitrogen to ICP-forest sites in Europe

摘要

The EMEP MSC-W Eulerian chemical transport model, and its predictions ofdeposition of acidifying and eutrophying pollutants over Europe, play akey role in the development of emission control strategies for Europe.It is important that this model is tested against observational data.Here we compare the results of the EMEP model with measured data from 160sites of the European Union/ICP Forest (Level II) monitoring network, forthe years 1997 and 2000. This comparison comprises: (a) Precipitationamount, (b) Total deposition of SO2−₄ to coniferous anddeciduous forests, (c) Wet deposition of SO2−₄, NO₃−and NH₄+ in open field sites, and (d) Concentrations ofSO2−₄, NO₃− and NH₄+ in precipitation.

Concerning precipitation, the EMEP model and ICP network showedvery similar overall levels (within 4% for 1997 and 11% for 2000). Thecorrelation was, however, poor (r2=0.15–0.23). This canbe attributed largely to the influence of a few outliers,combined with a small range of rainfall amounts for most points.Correlations between modelled and observed deposition values in this studywere rather high (r2 values between 0.4–0.8 for most componentsand years), with mean values across all sites being within 30%.The EMEP model tends to give somewhat lower values for SO2−₄,NO₃− and NH₄+ wet depositionto ICP, but differences in mean values were within 20% in 1997 and 30%in 2000. Modelled and observed concentrations of SO2−₄,NO₃− and NH₄+ in precipitation are very similaron average (differences of 0–14%), with good correlation betweenmodelled and observed data (r2=0.50–0.78). Differences betweenthe EMEP model and ICP measurements are thought to arise from a mixtureof problems with both the observations and model. However, the overallconclusion is that the EMEP model performs rather well in reproducingpatterns of S and N deposition to European forests.