Jerzy Bartnicki

EMEP Eulerian model for atmospheric transport and deposition of nitrogen species over Europe

As a part of EMEP, MSC-W in Oslo has the task to compute atmospheric transport and deposition of sulphur and nitrogen species over Europe. To perform this task, a three-dimensional Eulerian multilayer model was developed at MSC-W. This model has a 50 km horizontal resolution with 20 vertical layers, of which 10 are below 2 km level. Meteorological input, from a dedicated weather prediction model, is updated at 6-hour intervals. Emission inventories for NO x (NO+NO 2 ), NH 3 (and SO 2 ), submitted officially by the individual countries, are used as input data. In the model, NO x may be converted to PAN by the CH 3 COO 2 radical, or to nitrate (as HNO 3 in the gas phase and ammonium nitrate as particulate matter). The oxidation of NO x is assumed to proceed either by the OH radical in the gas phase, or as a night-time reaction via N 2 O 5 on deliquescent particles. Both OH and CH 3 COO 2 are prescribed as a function of solar zenith angle and cloud cover. Furthermore, ammonium sulphate is formed by NH 3 and sulphate. Excess NH 3 may react with HNO 3 , forming ammonium nitrate in an equilibrium reaction. Nitrogen is removed from the atmosphere by dry and wet deposition. A description of the model, as well as the model results, are presented and discussed. We also present a comparison of calculated concentrations and deposition fields for nitrogen with available measurements of concentrations and wet deposition for 1992.

Role of spatial and temporal variations in the computation of radiative forcing due to sulphate aerosols: A regional study

A high-resolution regional model for sulphate aerosols is used to investigate the effects of spatial and temporal averaging of radiative forcing. Mie theory is used to calculate the aerosol optical properties. The strong hygroscopic growth with increasing relative humidity is taken into account. The results for the regional area selected in our study (Europe and much of the North Atlantic) show that earlier global studies may have underestimated the magnitude of the radiative forcing due to sulphate aerosols by up to 30–40% due to coarse spatial and/or temporal resolution, at least over certain regions. This underestimation in global models of the water uptake is important for all strongly scattering hygroscopic aerosols. Our results imply that representation of relative humidity at even higher spatial resolution than used in this study may be of importance. This could be incorporated in models using subgrid-scale parametrizations of the relative humidity. Copyright

The European Nitrogen Assessment: Atmospheric transport and deposition of reactive nitrogen in Europe

Approaches Modelling provides a way of estimating atmospheric transport and deposition of N • r at the European scale. A description of the diff erent model types is provided. Current deposition estimates from models are compared with observations from European air chemistry monitoring networks. • Th e main focus of the chapter is at the European scale; however, both local variability and and intercontinental N • r transfers are also addressed.

Long-range tropospheric transport of uranium and plutonium weapons fallout from Semipalatinsk nuclear test site to Norway

A combination of state-of-the-art isotopic fingerprinting techniques and atmospheric transport modelling using real-time historical meteorological data has been used to demonstrate direct tropospheric transport of radioactive debris from specific nuclear detonations at the Semipalatinsk test site in Kazakhstan to Norway via large areas of Europe. A selection of archived air filters collected at ground level at 9 stations in Norway during the most intensive atmospheric nuclear weapon testing periods (1957-1958 and 1961-1962) has been screened for radioactive particles and analysed with respect to the concentrations and atom ratios of plutonium (Pu) and uranium (U) using accelerator mass spectrometry (AMS). Digital autoradiography screening demonstrated the presence of radioactive particles in the filters. Concentrations of (236)U (0.17-23nBqm(-3)) and (239+240)Pu (1.3-782μBqm(-3)) as well as the atom ratios (240)Pu/(239)Pu (0.0517-0.237) and (236)U/(239)Pu (0.0188-0.7) varied widely indicating several different sources. Filter samples from autumn and winter tended to have lower atom ratios than those sampled in spring and summer, and this likely reflects a tropospheric influence in months with little stratospheric fallout. Very high (236)U, (239+240)Pu and gross beta activity concentrations as well as low (240)Pu/(239)Pu (0.0517-0.077), (241)Pu/(239)Pu (0.00025-0.00062) and (236)U/(239)Pu (0.0188-0.046) atom ratios, characteristic of close-in and tropospheric fallout, were observed in filters collected at all stations in Nov 1962, 7-12days after three low-yield detonations at Semipalatinsk (Kazakhstan). Atmospheric transport modelling (NOAA HYSPLIT_4) using real-time meteorological data confirmed that long range transport of radionuclides, and possibly radioactive particles, from Semipalatinsk to Norway during this period was plausible. The present work shows that direct tropospheric transport of fallout from atmospheric nuclear detonations periodically may have had much larger influence on radionuclide air concentrations and deposition than previously anticipated.

EMEP Eulerian acid deposition model and its applications

The three-dimensional EMEP Eulerian grid model is under development at MSC-W. The application of the model is to simulate the atmospheric transport and deposition of acid pollutants in Europe’s atmosphere with ca. 50 × 50 km2 horizontal resolution. The Eulerian model replaces the traditional EMEP Lagrangian-trajectory model, used for routine calculations of country-to-country pollutant exchange. A brief model description is given as well as the estimation of model performance for 1996 data. The application of EMEP modeling results within the integrated assessment of the transboundary air pollution is described by taking as an example the second sulfur protocol of the Convention on Long-Range Transboundary Air Pollution, where results from an earlier EMEP Lagrangian model were used.

EMEP Eulerian model for acid deposition over Europe

A 3-D Eulerian acid deposition model has been developed at MSC-W. The model has approximately 50 km horizontal resolution with 20 vertical layers, of which 10 are below 2 km. Meteorological input, from a dedicated weather prediction model, is updated at six-hour intervals. Emission inventories for SO2, NOx (NO + NO2) and NH3, reported officially by individual countries, are used as input data. A brief description of the current model version is given, as well as the model results for sulphur compounds in 1992. We present a comparison of calculated and measured SO2 and SO4 annual (scatter plots) and daily concentrations (time-series) at selected locations 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.

SEVERE NUCLEAR ACCIDENT PROGRAM (SNAP) A REAL TIME DISPERSION MODEL

The Chernobyl nuclear accident in April/May 1986 showed that Norway was not well prepared for this kind of emergency situation1. Scientists who had relevant information felt frustrated because there was no clear answer to the question: where and how their information should be delivered, assessed and synthesized1. In addition, there was no dispersion model implemented in an operational environment, ready to simulate and forecast atmospheric transport and deposition of the radioactive pollutants over Europe based on real-time meteorological data. This was also the situation in most countries in Europe2.

Atmospheric transport of radioactive debris to Norway in case of a hypothetical accident related to the recovery of the Russian submarine K-27

The Russian nuclear submarine K-27 suffered a loss of coolant accident in 1968 and with nuclear fuel in both reactors it was scuttled in 1981 in the outer part of Stepovogo Bay located on the eastern coast of Novaya Zemlya. The inventory of spent nuclear fuel on board the submarine is of concern because it represents a potential source of radioactive contamination of the Kara Sea and a criticality accident with potential for long-range atmospheric transport of radioactive particles cannot be ruled out. To address these concerns and to provide a better basis for evaluating possible radiological impacts of potential releases in case a salvage operation is initiated, we assessed the atmospheric transport of radionuclides and deposition in Norway from a hypothetical criticality accident on board the K-27. To achieve this, a long term (33 years) meteorological database has been prepared and used for selection of the worst case meteorological scenarios for each of three selected locations of the potential accident. Next, the dispersion model SNAP was run with the source term for the worst-case accident scenario and selected meteorological scenarios. The results showed predictions to be very sensitive to the estimation of the source term for the worst-case accident and especially to the sizes and densities of released radioactive particles. The results indicated that a large area of Norway could be affected, but that the deposition in Northern Norway would be considerably higher than in other areas of the country. The simulations showed that deposition from the worst-case scenario of a hypothetical K-27 accident would be at least two orders of magnitude lower than the deposition observed in Norway following the Chernobyl accident.