9th International Conference on Remarks of the scientifc committee: Harmonisation within Atmospheric accepted 1 2 3 4 5 Dispersion Modelling for Regulatory Purposes good poor Garmisch-Partenkirchen Germany June 1 – 4, 2004 poster lecture Topic: Abstract No: Abstract Submission Form Details of the submitting author / abstract presenter: Surname: Fay First Name: Barbara Title: Ms Address: German Weather Service, Research and Development, Air Pollution Modelling, Frankfurter Str. 135, 63067 Offenbach, Germany Telephone: ++49-69-8062 2748 Fax: ++49-69-8062 3759 e-mail: firstname.lastname@example.org Details of the abstract: Title of the abstract: EVALUATION AND COMPARISON OF OPERATIONAL NWP AND MESOSCALE METEOROLOGICAL MODELS FOR FORECASTING URBAN AIR POLLUTION EPISODES - HELSINKI CASE STUDY I prefer an oral presentation a poster presentation Please indicate into which section of the conference your contribution may fit best: Validation and inter-comparison of models: Model evaluation methodology Regulatory models: country review Review of experiences using models when implementing the EU directives Short distance dispersion modelling Urban scale and street canyon modelling: Meteorology and air quality Mesoscale meteorology and air quality modelling Environmental impact assessment: Air pollution management and decision support systems EVALUATION AND COMPARISON OF OPERATIONAL NWP AND MESOSCALE METEOROLOGICAL MODELS FOR FORECASTING URBAN AIR POLLUTION EPISODES - HELSINKI CASE STUDY Fay B(1), Neunhäuserer L(1), Baklanov A(3), Bjergene N(5), Kukkonen J(4), Palau J L(2), Perez- Landa G(2), Rantamaki M(4), Rasmussen A(3), Valkama I(4) (1) German Weather Service, Offenbach, Germany (2) CEAM, Valencia, Spain (3) Danish Meteorological Institute, Copenhagen, Denmark (4) Finnish Meteorological Institute, Helsinki, Finland (5) Norwegian Meteorological Institute, Oslo, Norway Predicting potentially harmful air pollution episodes is a major challenge in forecasting urban air pollution. Urban air quality information and forecasting systems (UAQIFSs) were established by city authorities especially after the implementation of the stricter European Air Quality Directives. Nested numerical weather prediction models have recently approached city scale resolution, and UAQIFSs may therefore be improved by using the output of operational weather prediction and mesocale meteorological models. This study is part of the European Union FP5 project FUMAPEX (Integrated Systems for Forecasting Urban Meteorology, Air Pollution and Population Exposure) and the COST 715 action. Simulations are performed with 4 numerical weather prediction (NWP) models of major European weather services (the HIRLAM model versions of the Danish, Finnish, and Norwegian meteorological services, the Lokalmodell of the German Weather Service/COSMO modelling consortium) and the mesoscale meteorological models MM5 and RAMS. The models are run with their specific operational data assimilation, numerics, and parameterisation and also as nested versions with higher resolution down to 1km but without improved parameterisations. An intense Helsinki wintertime inversion episode in Dec 1995 and springtime dust episodes in March 1998 and April 2002 are investigated. Meteorological predicting variables with relevance to urban meteorology and air quality modelling (such as temperature inversion, atmospheric stability, wind speed, surface heat fluxes) are evaluated against measurements and inter-compared between the models using various quantitative deterministic tests and statistical model performance measures. Some improvements (e.g. in thermal inversions and wind speeds) are achieved with higher model resolution. Remaining deficiencies in model results and the corresponding necessity of modified parameterisations for application of these models in the urban environment are explained. Recommendations for the improvement of boundary layer parameterisations and surface characteristics in meteorological forecast models for UAQIFSs are formulated and set in relation to the current improvement strategies in FUMAPEX.