Sabine Banzhaf

Curriculum vitae of the LOTOS–EUROS (v2.0) chemistry transport model

The development and application of chemistry transport models has a long tradition. Within the Netherlands the LOTOS–EUROS model has been developed by a consortium of institutes, after combining its independently developed predecessors in 2005. Recently, version 2.0 of the model was released as an open-source version. This paper presents the curriculum vitae of the model system, describing the model’s history, model philosophy, basic features and a validation with EMEP stations for the new benchmark year 2012, and presents cases with the model’s most recent and key developments. By setting the model developments in context and providing an outlook for directions for further development, the paper goes beyond the common model description. With an origin in ozone and sulfur modelling for the models LOTOS and EUROS, the application areas were gradually extended with persistent organic pollutants, reactive nitrogen, and primary and secondary particulate matter. After the combination of the models to LOTOS–EUROS in 2005, the model was further developed to include new source parametrizations (e.g. road resuspension, desert dust, wildfires), applied for operational smog forecasts in the Netherlands and Europe, and has been used for emission scenarios, source apportionment, and long-term hindcast and climate change scenarios. LOTOS–EUROS has been a front-runner in data assimilation of ground-based and satellite observations and has participated in many model intercomparison studies. The model is no longer confined to applications over Europe but is also applied to other regions of the world, e.g. China. The increasing interaction with emission experts has also contributed to the improvement of the model’s performance. The philosophy for model development has always been to use knowledge that is state of the art and proven, to keep a good balance in the level of detail of process description and accuracy of input and output, and to keep a good record on the effect of model changes using benchmarking and validation. The performance of v2.0 with respect to EMEP observations is good, with spatial correlations around 0.8 or higher for concentrations and wet deposition. Temporal correlations are around 0.5 or higher. Recent innovative applications include source apportionment and data assimilation, particle number modelling, and energy transition scenarios including corresponding land use changes as well as Saharan dust forecasting. Future developments would enable more flexibility with respect to model horizontal and vertical resolution and further detailing of model input data. Published by Copernicus Publications on behalf of the European Geosciences Union. 4146 A. M. M. Manders et al.: Curriculum vitae of the LOTOS–EUROS (v2.0) chemistry transport model This includes the use of different sources of land use characterization (roughness length and vegetation), detailing of emissions in space and time, and efficient coupling to meteorology from different meteorological models.

Sensitivity of Modelled Land Use Specific Nitrogen Deposition Fluxes to Improved Process Descriptions

In this study, the chemistry transport model (CTM) LOTOS-EUROS is used to calculate the deposition fluxes of eutrophying and acidifying reactive nitrogen (Nr) to ecosystems in Germany. In the last years important developments have been made for the modelling of the budget of Nr. The new model version has changed the spatial explicit budget calculations across Germany and was thoroughly evaluated with respect to pollutants concentrations and deposition fluxes. The results revealed that the balance between dry and wet deposition is sensitive to the updates in the process descriptions impacting the pollutants transport distances. A comparison to observations showed an improvement of the new model version compared to the pre-developments model version.

Response of SIA Concentrations Across Germany to Emission Changes During PM10 Episodes in Spring 2009

The Chemistry Transport Model (CTM) REM-Calgrid (RCG) has been applied to investigate the non-linear relationship between emission changes and modelled SIA (=SO4 + NO3 + NH4) concentrations for a high PM10 episode in spring 2009. Emissions were reduced for the model domain only and the model domain including Boundary Conditions. It was found that the effectiveness of emission reductions increases with increasing emission reduction area whereas results were least dependent on the size of emission reduction area for ammonia emission changes.

Can We Explain the Observed Decrease in Secondary Inorganic Aerosol and Its Precursors Between 1990 and 2009 over Europe Using LOTOS-EUROS?

In this study we investigate the ability of the Chemistry Transport Model (CTM) LOTOS-EUROS to explain the observed decrease in secondary inorganic aerosol (SIA) and its precursors between 1990 and 2009 over Europe. The model explicitly accounts for cloud chemistry and aerosol thermodynamics. The results have shown that the model largely captures the observed trends in SIA and its precursors’ concentrations while it underestimates the interannual variability. Using a source-apportionment module the amount of SIA formed per unit emission was traced for a number of regions. The results show 20–50 % more efficient SO4 2− formation in 2009 compared to 1990, whereas the change in NO3 − formation per unit NOx emission is lower (−10 % to +20 %) for the same time period.

Measuring and Modeling Wet Deposition Fluxes in the Netherlands and Europe

The Dutch National Precipitation Chemistry Monitoring Network measures the wet deposition fluxes of acidifying and eutrophying compounds and heavy metals over the Netherlands since 1978. Recent measurements of sulfate, ammonium and nitrate of this precipitation network are used to validate the outcome of the new wet deposition module implemented into the regional air quality model LOTOS-EUROS. The old wet deposition module only included below-cloud scavenging, whereas the new wet deposition module takes into account below-cloud and in-cloud scavenging. Both processes are implemented such that the effect of the saturation of rain droplets on the scavenging efficiency is included. A simple parameterization, based on the liquid water content data from ECMWF, is used to distinguish between regions in which respectively below-cloud or in-cloud scavenging occurs. In general, it is found that the combination of below-cloud and in-cloud scavenging increases the net scavenging process in the LOTOS-EUROS model simulations; hence the wet deposition fluxes are increased. These increased wet deposition fluxes in the model simulations are evaluated at the sites of the precipitation network in the Netherlands and show a better agreement as compared to results of simulations performed with the old wet deposition module. Finally the wet deposition fluxes are also evaluated at the sites of the European EMEP monitoring stations: a similar improvement is found again between the measurements and model results.

Wet Deposition: Model Development and Evaluation

The Chemistry Transport Model REM-Calgrid (RCG) has been improved by implementing a more detailed description of aqueous-phase chemistry and wet deposition processes including droplet pH. A sensitivity study on cloud and rain droplet pH has been performed to investigate its impact on model sulphate production and gas wet scavenging. Air concentrations and wet deposition fluxes of model runs applying differing droplet pH have been analysed and compared to observations. It was found that droplet pH variation within atmospheric ranges affects modelled air concentrations and wet deposition fluxes significantly.