Calculating nitrogen deposition in Europe

Nitrogen deposition calculations for Europe were performed by separate models describing the long-range transport of ammonia and oxidized N. A linearized version of a non-linear atmospheric chemistry model was used for calculating oxidized N. Model computations were found to be consistent with the observed spatial pattern of wet nitrate deposition in Europe. Interannual meteorological variability was estimated to cause a typical year-to-year variation in annual oxidized N deposition of about 6 to 10%. Nitrogen deposition was computed for several NO _x emissions reduction scenarios. These scenarios were derived from an OECD study and applied to the 27 largest countries in Europe. Most reduction scenarios affected the deposition pattern of oxidized N, but the most extreme NO _x emission reduction scenario did not change very much the overall pattern of total (oxidized N plus ammonia N) N deposition. Depending on the desired level of environmental protection, it may be necessary to reduce ammonia emissions in addition to NO _x emissions in order to reduce N deposition in Europe.     

An Eulerian model for atmospheric transport of heavy metals over Europe: Model description and preliminary results

This paper presents the Heavy Metals Eulerian Transport (HMET) model and simulation results for Europe for 1985. The HMET model takes into account emission, atmospheric transport and deposition of As, Cd, Pb and Zn computed on the EMEP grid system. Meteorological inputs consist of the velocity field at 925 hPa, precipitation and mixing height. Velocity field and precipitation are updated every 6 hr during the model run. New values of mixing height are available every 24 hr. The dry deposition velocities for each metal are variable in space and depend on the particle distribution function for each particular metal. Wet deposition is proportional to the precipitation intensity for the previous 6 hr and a constant scavenging ratio. Model equations are solved by means of the positive definite pseudospectral method which provides accurate numerical solutions for the advection problem. Comparison of the model results with available observations for 1985 indicate a good agreement for Cd and Pb, sufficient egreement for As and serious underestimation for Zn. Since the number of available observations for heavy metals in Europe in 1985 is relatively small, the model results presented in this paper should be considered as preliminary. However, the HMET model performance in computing these results shows that it can be easily and efficiently used as an operational tool and is especially useful for estimating transboundary transport of heavy metals in Europe.     

Integrated Assessment Modeling of Air Pollution in Four European Countries

The integrated assessment modeling on acid rain has incorporated several related effects and pollutants into a multi-pollutant/multi-effect approach, resulting in complex integrated models and policy assessments. The development and implementation of effects-oriented cost-effective emission reduction strategies in Europe are based on integrated assessment models. The project on national integrated assessment modeling in Finland, Denmark, Spain and Sweden aimed to support the national evaluation of European emission reduction strategies. The tasks covered the comparison of inventories and projections for emissions of sulfur, nitrogen oxides, ammonia and volatile organic compounds, assessment of control techniques and related costs, concentration and deposition scenarios to estimate environmental effects of acidification, eutrophication and ground-level ozone and their temporal aspects, uncertainty analyses on both individual modules and whole integrated models, and dissemination of results to stakeholders. The integrated assessment modeling provided a consistent framework for the harmonization of input data and in-depth scientific research tasks on emissions, pollutant loading and impacts including comprehensive uncertainty analyses, and facilitated the dissemination of knowledge to policy-makers.     

Computing atmospheric transport and deposition of heavy metals over Europe: Country budgets for 1985

The Heavy Metal Eulerian Transport (HMET) model has been used to calculate the exchange of As, Cd, Pb and Zn between European countries in 1985. The model was run separately for each emitter country and the computed deposition field was used to calculate the contribution of the emitter to each receptor country. The results of these computations are presented in the form of a country budget matrix for each metal. Accuracy of such computations is dependant on the size and linearity of the numerical method applied to the transport equation. Exchange of heavy metals due to atmospheric transport over Europe is significant. Approximately 30% to 90% of the heavy metals emitted from each country is deposited in other countries. The remaining mass is deposited in European seas, Atlantic Ocean and transported outside the model domain. The largest part of the emission from each country is deposited in the same country. The next largest fraction is transported to the nearest neighbors. The results indicate also a significant long range ransport of heavy metals to the Soviet Union. This is partly justified by the size and location of this receptor country, as well as, the prevailing meteorological conditions in Europe. However, this large transport to USSR is slightly overestimated due to some artificial properties of the numerical method applied to basic model equations. In addition to the country budget, export versus import and emission versus deposition of metals were analyzed for each country. The largest positive difference between export and import was found for Poland, German Federal Republic and Yugoslavia (As, Cd and Zn), and United Kingdom, Italy and Belgium (Pb). The Soviet Union and Czechoslovakia are the countries where import of all metals is significantly larger than export. When emission versus deposition of heavy metals is analyzed, the Soviet Union has much higher emissions than deposition of all metals compared to other European countries.     

Atmospheric models and acidification: Summary and conclusions of the Warsaw II meeting on atmospheric computations to assess acidification in Europe

Three topics are discussed in this report: sensitivity/uncertainty analysis of long range transport models, the interface between atmospheric models of different scales, and linkage between atmospheric and ecological models. In separate analyses of long range transport models, it was found that uncertainty of annual S deposition was mostly affected by uncertainty of wind velocity, mixing height and wet deposition parameterization. Uncertain parameters collectively caused S deposition errors of around 10–25% (coefficient of variation) in the models examined. The effect of interannual meteorological variability on computed annual S deposition was relatively small. Different methods were presented for combining models of regional and interregional scale. It was found to be more important to include interregional information in regional-scale models for annual computations compared to episodic computations. A variety of linkage problems were noted between atmospheric and ecological models. The vertical distribution of pollutants and ‘forest fittering’ of pollutant deposition were found to be important in ecological impact calculations but lacking in the output of most interregional atmospheric models.