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    Environment

Text "Environment"	Harry Vereecken, Heiner Geiß, Institute of Chemistry and Dynamics of the Geosphere, Research Centre Jülich
Aircraft Emissions in the Tropopause Region	Adolf Ebel, Johannes Hendricks, Johanna Kowol-Santen, Elmar Lippert and Raimund Meyer, EURAD, Institute for Geophysics and Meteorology, University of Cologne
Summer Smog in Berlin	Adolf Ebel, Michael Kerschgens, Michael Memmesheimer, EURAD, University of Cologne; Heiner Geiß, Institute for Chemistry of the Polluted Atmosphere, Research Centre Jülich; Rainer Friedrich, Burkhard Wickert, Institut für Energiewirtschaft und Rationelle Energieanwendung, University of Stuttgart
Dispersion of Contaminants in the Soil	Harry Vereecken, Institute for Petroleum and Geochemistry, Research Centre Jülich

Text "Environment"

The research activities in environmental precaution research are characterized by a close linkage of measurement and numerical simulation. Only a combination of theory and practice provides a way of deriving a complete picture of the complicated processes in nature and enables predictions. This includes field measurement campaigns and laboratory experiments as well as mathematical modelling with the aid of massively parallel supercomputers. The interaction between these approaches will make it possible to improve our understanding of natural processes and allows us an efficient application of our knowledge in environmental research.

The data obtained in the field and laboratory serve as a basis for new theories which can be converted into computer models and further developed. In those mathematical models and in "simulation experiments" on the computer, the interaction between the different processes can then be better understood and interpreted.

Examples are research into the formation of summer smog in the environment of big cities, the influence of aircraft emissions on the atmosphere and the transport of contaminants in soils and groundwater.

In the atmosphere, the spatial distribution of e.g. ozone and nitrogen oxide concentrations in the air and their variation over time under different meteorological conditions is calculated for various emission scenarios using complex atmospheric chemistry and transport models. The results can be used to evaluate emission reduction strategies and in future also for more precise summer smog forecasts. Atmospheric simulation experiments are also more and more used for planning field measurement campaigns and calculating the potential stress on ecosystems due to human activities.

The evaluation and quantification of the long-term consequences of soil and groundwater contaminations are of increasing significance for the long-term protection of our water resources. As in the atmosphere, the correct physical formulation and exact mathematical description of the transport process is the basis for the success of model calculations.

Furthermore, the quality of the simulation results depends significantly on the quality of the measured physical, chemical and biological boundary conditions and parameters in the soil. A precise characterization of these parameters is above all required due to the fact that, unlike the atmosphere, soils and aquifers are not homogeneous but consist of an interstratification of different sediments. The application of geophysical measuring methods as well as new methods based on induced magnetic fields furnish a contribution to a more precise description of the subsoil and improve the results of computer programs.

(Harry Vereecken, Heiner Geiß, Institute of Chemistry and Dynamics of the Geosphere, Research Centre Jülich)

Aircraft Emissions in the Tropopause Region

The above picture shows the global distribution of nitrogen oxide emissions [t/a] (coloured) due to cruising traffic at 11 - 12 km altitude after an emission inventory by McInnes and Walker. The white dots reflect the activity distribution of tropopause foldings. A higher activity of tropopause folding events is observed at northern midlatitudes where a larger percentage of aircraft movements take place.

The diagram on the left shows the tropopause as a 1.6 PVU surface in the North Atlantic Corridor on 15.10.1993 at 0:00 UTC (blue area). Additionally plotted is the distribution of exhaust gases (tracers) caused by cruising traffic which essentially takes place at altitudes between 9 and 13 km (red area). It can be seen that the distribution of aircraft emissions is influenced by the dynamics of the tropopause region. The aircraft exhausts are transported downwards in the region of the tropopause folding south of Greenland. This is based on results of the mesoscale EURAD-TS (European Air Pollution and Dispersion model for the Troposphere and the lower Stratosphere) model system with a horizontal grid resolution of 50 km and a vertical extension from the ground to 10 hPa altitude.

The model calculations were performed within the framework of the BMBF-supported collaborative programme "Pollutants in Aviation" within the STRATFLUT project (simulation of the transport and chemical transformation of aircraft emissions in the tropopause region).

(Adolf Ebel, Johannes Hendricks, Johanna Kowol-Santen, Elmar Lippert and Raimund Meyer, EURAD, Institute for Geophysics and Meteorology, University of Cologne)

Summer Smog in Berlin

Ozone is formed under solar irradiation from nitrogen oxides (NO_x) and hydrocarbons. The formation of ozone therefore takes place primarily on midsummer days near urban agglomerations. This leads to high physically harmful ozone concentrations which may last for several days (summer smog). The diagrams show the concentrations of NO_x and ozone in the vicinity of Berlin at 8:00 in the morning and around 16:00 in the afternoon. It can be seen that the NO_x values are high and the ozone values low in the morning. In the afternoon, the highest ozone values occur with winds from the southeast about 50 to 100 km northwest of Berlin. Elevated NO_x values are only found in the urban area and along the motorways at about 16:00. Work is being carried out within the framework of the BMBF tropospheric research programme (Berlin Ozone Experiment 1998, BERLIOZ).

(Adolf Ebel, Michael Kerschgens, Michael Memmesheimer, EURAD, University of Cologne; Heiner Geiß, Institute for Chemistry of the Polluted Atmosphere, Research Centre Jülich; Rainer Friedrich, Burkhard Wickert, Institut für Energiewirtschaft und Rationelle Energieanwendung, University of Stuttgart)

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Dispersion of Contaminants in the Soil

In Jülich, a software package has been developed with which the transport of contaminants in groundwater can be predicted. During several years of laboratory and field work, soil samples were taken in a field at Krauthausen near Jülich and examined for their hydraulic conductivity and storage capacity. In order to characterize groundwater flow, the researchers applied nontoxic fluorescence dyes and regularly analysed their fate. The data obtained were used to develop a computer model which precalculates the mobility of contaminants. The program package consists of three parts: "Trace" calculates the groundwater flow; the program runs on a parallel computer. Based on the results obtained, "Partrace" then calculates the transport of contaminant particles. Finally, the results are visualized on a graphics computer. The picture shows the expansion of a contaminant cloud (red) in the course of several weeks. Rock layers impermeable to water are shown in grey.

(Harry Vereecken, Institute for Petroleum and Geochemistry, Research Centre Jülich)

Introduction	Super- computing	Astro- physics	Elementary Particles	Many Particles	Polymers	Chemistry	Environment	Other Fields