Intercomparison of the wet deposition of NH4(+), NO3 and SO4(2-) estimated by several air quality models for one of the EuroDelta3 campaigns
Résumé
The more and more extended use of models in a large variety of air quality management activities leads to increased requirements for the credibility and robustness of model results. In the framework of the UNECE Task Force on Measurement and Modelling (TFMM), under the Convention on Long-range Transboundary Air Pollution (LRTAP), the EURODELTA project is contributing to a better knowledge on how well current European models are able to reproduce observed pollutant air concentrations and deposition, trying to explain the differences in their results. Within the EURODELTA3 project community research, seven regional models (CAMx, CHIMERE, EMEP MSC-W, LOTOS-EUROS, MINNI, REM-CALGRID and CMAQ) have been evaluated in terms of wet deposition for one of the intensive EMEP measurement periods in 2009 (25 Feb - 26 Mar). All models were run for the same domain and resolution and with the same input data (emissions, meteorology, and boundary conditions), with the exception of REM-CALGRID and CMAQ using different meteorology. The evaluation of model performance was focused on the wet deposition of NH4(+), NO(-)3 and SO4(2-) All in all, most of the models show a better agreement with observations at sites with relatively low and medium measured accumulated wet deposition values. In the case of NO3(-) , there is a general tendency to underpredict the highest accumulated wet depositions, with some differences between the models: CHIMERE, EMEP and LOTOS calculate higher values than the remaining models for this period, being closer to observations. For NH4(+), most of the models underestimate the highest observed values. In this case, EMEP calculates the highest accumulated wet depositions, in a better agreement with observed values, except for some overestimation at a few sites. In the case of SO4(2-) wet deposition, CMAQ is providing the best performance, with a good agreement with observations also for the high observed values. This fact seems to be related to the natural SO4(2-) emissions associated to sea salt processes that this model considers. Unfortunately differences between models in the Southeastern part of the domain could not be evaluated due to the lack of observations over that area.