Elsevier Science Ltd
Oxford, United Kingdom|
TNO Milieu, Energie en Procesinnovatie
|Source:||Ebel A.Singh H., Proceedings of the 1995 10th EUMAC Workshop, 30 August 1995 - 1 September 1995, Koln, Germany, 19, 31, 3259-3279|
Environment · Emission reduction response · Intercomparison · Regional air quality models · Air pollution control · Industrial emissions · Mathematical models · Meteorology · Ozone · Photochemical reactions · Photochemical dispersion model · Regional modeling · Air quality · Europe
An intercomparison study has been performed with four photo-oxidant dispersion models (EMEP, EURAD, LOTOS and REM3) which are currently capable of performing photo-oxidant formation calculations over larger path of Europe. The models, in principle, were run in the mode in which they are normally used, with their own input data and process descriptions. No attempt has been made to harmonize the input data. The study focused on the simulation of a six day episode (31 July-5 August, 1990) with relatively high observed ozone levels over northwest and central Europe (up to 140 ppbv) and which ended by a frontal passage. The study was mainly restricted to an analysis of the behaviour at four receptor sites across the centre of each modelling domain. Differences in yearly averaged anthropogenic emissions are in the order of 10% only. However, episode specific hourly emissions, both anthropogenic and biogenic, show much larger differences. Here up to 40% differences for anthropogenic emissions are found for central Europe while biogenic emissions differ even up to a factor 2-3. The meteorological data base for all models is created from the synoptic measurement network by different techniques. This can result in quite different model inputs as e.g. the value of the mixing height or trajectories. Other model inputs, e.g. dry deposition velocities or photolysis frequencies, show much closer agreements than expected from their derivation through different parameterizations. Model performance for the regional scale could only be observed for ozone. In central Europe, the large-scale ozone patterns are quite similar for all models. Here the temporal evolution at some receptor sites shows also a reasonable agreement with observations. However, in case a multi-component evaluation is possible it can be expected that differences between models can be revealed to a greater detail than was possible here. The model responses to emission reductions show substantial differences although the direction of the responses generally agree. The most complex model (EURAD) has the most pronounced response to anthropogenic emission reductions. The treatment of the biogenic emissions can have a large impact on scenario simulations.