Department description

The overall strategy of the Department of Atmospheric Environment is to maintain a vertically integrated research profile (i.e., spanning basic, applied, experimental, modelling, and systems research) which supports the development of leading internationally recognised air pollution modelling and monitoring systems, for both assessment and prognosis.

Air pollution is caused by a complex interaction involving natural and anthropogenic emissions and meteorology. Emissions from industry, traffic, and heating systems represent the primary causes of air pollution, and emissions regulations are therefore designed in order to assure that air pollution levels do not exceed pre-designated limits. The quality of human health, agricultural output, the conditions of forests, and risks of marine eutrophication are all examples of air pollution effects. In order to build scientifically-based models and prediction systems, and provide the best advice to the Ministry of Environment and Energy, the scope of work in the Department of Atmospheric Environment focuses on three aspects of the air pollution problem.

First, efforts are placed on building better performing air pollution and assessment model tools, using better parameterizations of the governing atmospheric processes, better data bases, and a better understanding of effects and impacts over all sectors.

Second, monitoring of air pollution levels is carried out, both in order to establish trends and to evaluate the impact of protocols and other government decisions.

Finally, both scientific results and monitoring data are delivered to public, government authorities, and/or scientific societies in a timely way. Regulation and enforcement are tasks within the Danish EPA and municipal authorities, and are therefore not addressed by the Department of Atmospheric Environment.

The Department undertakes mathematical modelling and field measurements of air pollution in a mutually complementary manner. Monitoring data collected under national and international programmes are used in the scientific studies. These endeavours involve collaboration with other NERI departments and outside institutions which have complementary expertise. Funding for these activities is provided by a variety of national and international sources.

At NERI, emission inventories of air pollutants are compiled on a regular basis by  the Department of Policy Analysis with assistance from the Department of Atmospheric Environment. The inventories support model development and are delivered to international authorities. Because the emissions data are gathered in response to a variety of international agreements, a variety of temporal and geographical scales is considered. One of the primary customers is the European Environment Agency (EEA).

Monitoring of the atmospheric concentration and deposition of air pollutants has both regulatory and scientific relevance. Pollution levels in a number of Danish cities have been monitored for several years within the Danish Air Quality Monitoring Programme (Danish abbreviation: LMP), the emphasis originally having been on sulphur dioxide and particulates. In recent years, however, urban levels of these pollutants have decreased as a result of the more widespread use of natural gas, the establishment of district heating and the use of excess heat from power plants. At the same time, the increase in urban car traffic has resulted in increased levels of nitrogen oxides and organic compounds. The emphasis of the monitoring programme has therefore shifted to compounds relevant to photochemical air pollution and carcinogenic pollutants such as PAHs, POPs and VOCs, which are analysed in collaboration with the Department of Environmental Chemistry.

A subset of the monitoring data base is placed on the Internet within one day after data collection. These data are freely accessible to all users.

The Department has been measuring pollutant concentrations and deposition in rural areas for many years within the framework of EMEP (the European Monitoring and Evaluation Programme), and annually publishes a report on the state of the environment in rural areas. More specific investigations include deposition and ion-balance in forest ecosystems and deposition in Danish coastal waters. The ion balance programme complements the background monitoring programme, and it also provides the database required to parameterize the atmospheric chemical load on forest ecosystems. The Department is involved in the national monitoring of critical loads in collaboration with other NERI departments (Department of Terrestrial Ecology and the Department of Policy Analysis). Chemical deposition to coastal marine areas has received special attention, due to its importance in eutrophication and global change. These studies examine coupled physical, chemical and biological processes. This project has close collaboration with the Department of Marine Ecology and Microbiology, and a large number of international institutions.

Arctic air pollution caused by long-range transboundary transport is studied in Greenland by field measurements and mathematical modelling. The aim is to identify source areas and atmospheric transport paths and to quantify the concentration levels and deposition rates.

The monitoring programme consists of two activities, located in Northeast and in West Greenland, respectively.

In both these monitoring projects measurements of acidifying components and heavy metals are carried out for assessment of atmospheric concentration levels and seasonal variations. Also gaseous Mercury and Ozone are measured with high time resolution. The results are also used for verification and improvement of model calculations of atmospheric transport and chemical transformations. Application of receptor modelling of the pollution composition permits identification and quantification of the source types that influence the atmospheric pollution in these two regions. It is also expected to lead to better transport models.

The modelling programme is based on the operation, application and maintenance of the Danish Eulerian hemispheric model (DEHM). Results on origin, transport, and deposition of acidifying contaminants and heavy metals on land and sea surfaces in the Arctic are essential for interpretation and understanding the Arctic air pollution. A particular feature of the model is the module for hemispheric transport and chemistry of mercury and ozone. These two components seem to be strongly connected in the Arctic, and the model will be further developed and tested in order to identify the origins and transport paths of this highly toxic metal and to quantify the deposition to the sea surfaces in the Arctic.

The assessment and scenario project aims at a national assessment of the state of the atmospheric environment in the high Arctic and its development in the 1990s. The results and the models in the Danish AMAP project will be also used in future international AMAP assessments and for scenario calculations of the effect in the Arctic of emission reductions in mid-latitude source areas.

These studies are a part of the international AMAP project (Arctic Monitoring and Assessment Programme) which are carried out in collaboration between institutes from Canada, Denmark, Finland, Iceland, Norway, Russia, Sweden and the USA. In Denmark the project is supported through the DANCEA funds.

Arctic air pollution caused by long-range transboundary transport is being studied in Greenland by field measurements and mathematical modelling. Moreover, studies are made of the correlation between atmospheric concentrations of pollutants and deposit layers in the icecap. This forms part of the SAGA (Studies of Arctic Gases and Aerosols) research projects.

The physical and chemical processes involved in dispersion are being investigated on all scales. Work is undertaken on parameterizing important processes and constructing a hierarchy of dispersion models for various scales. For example, a long-range, Eulerian transport model (the Danish Eulerian Model, or DEM) is used to predict pollutant concentrations and deposition on a European scale. The model includes detailed modelling treatment of atmospheric chemistry and is used to study the impact of environmental regulations. A second model - the Northern hemispheric Eulerian model - focuses on sulphur compounds with special emphasis on Arctic pollution episodes. The Department's work within meso-scale modelling involves the improvement of the Atmospheric Chemistry and Deposition (ACDEP) model; the ACDEP model focuses on determining nitrogen deposition in marine areas at a high resolution.

On the urban scale, the Department has developed the Operational Street Pollution Model (OSPM) for studying the local gradients and pollutant fluctuations in street canyons under a variety of conditions on a one-hour time scale. An important feature of the model is the concept of physical recirculation in street canyons; OSPM incorporates the chemistry of NO, NO₂ and ambient ozone. With support from the Nordic Council of Ministers and the Danish Environmental Research Programme, the Department works on generalising urban street canyon models, so as to address traffic policy issues.

The Department is also active within the field of air quality models for regulatory use. The so-called OML model (a modern, Gaussian point source model), is widely used in the regulatory community. Work is in progress aimed towards including more facilities in the model.

A new model has been recently been added to the inventory of models, i.e., the Danish Rimpuff Eulerian Atmospheric Model (DREAM). The DREAM combines the best features of a high resolution puff dispersion model with the lower resolution Danish Eulerian Model. With the DREAM, one can specify the receptor point for a plume at any distance from the source and calculate dispersion and exposure statistics for any pre-specified interval.

The increased atmospheric concentration of NOx has led to a more than two-fold increase in the tropospheric concentration of ozone in recent years. As the ozone concentration frequently exceeds safe levels for human and ecosystem health, the Department studies pollutants involved in ozone photochemistry. The complex composition of nitrogen compounds is investigated in detail to elucidate the importance of NOx for the formation of ozone and harmful nitrogen products. In addition, VOC’s and aerosols are included among the compounds which the Department scientists study, in order to identify adverse effects. Benzene, in particular, has received special attention due to its great health risk.

The Department of Atmospheric Environment has a staff of approximately 60, comprising 24 senior scientists, scientists and engineers, 2-3 guest scientists, 32 technical and administrative personnel, and it is currently supervising 4 PhD students.