Project reclip:more - overview: Objectives, tasks and results 2004-2005

Abstract: The rising public discussion about climate change has raised the concern about consequences those changes might have for natural environment and human society. Conducting climate impact assessments requires reliable regional climate change predictions. Besides changes in mean temperature and yearly precipitation, most severe impacts of climate are often caused by extreme events (droughts, flooding rain, floods, storms, avalanches) that occur on a time scale of some days to weeks. Thus climate impact assessment requires information not only on a fine spatial, but also with a high temporal resolution. Furthermore, climate-vulnerable systems are affected by several climate parameters, which are related to each other. Information provided for climate impact research has to reproduce these relationships with high accuracy in order to deliver a meteorologically consistent image of future climate. Global Circulation models (GCM´s) do not provide detailed spatial features of the general atmospheric circulation as they show only coarse horizontal resolution, which is currently 120 kilometres in the European mid latitudes. Thus for assessing regional future climate impacts at meso- and microscale resolutions it is necessary to provide regional climate models (RCM´s) to deliver high resolution datasets for future climate. The 3-year project reclip:more (Research for Climate Protection: Model Run Evaluation) is developed and financed by the Austrian Research Centres - ARC systems research GmbH (ARC-sys). It concentrates: . on applying regional climate models . on statistical downscaling, . on conducting sensitivity and validation analyses . through test, development, adaptation or improvement of modelling and validating techniques, aiming at scientifically sound transient data sets describing the future climate for the entire Alpine area for climate impact research at local to regional scale. Thus it will provide for the fist time long term regional climate model runs for Austria providing data with sufficient spatial and temporal resolution completed with sensitivity and validation analysis to judge the plausibility and depict the range and variation of the results. ARC-sys has therefore invited 4 Austrian institutions engaged in climate modelling to establish a strong climate modelling research team: . Department of Meteorology and Geophysics, Vienna University (2 teams:IMG-ALADIN, IMG-VERA) . Institute of Meteorology, Vienna Univ. of Natural Resources and Applied Life Sciences (BOKU-Met) . Wegener Center for Climate and Global Change, University of Graz (WegCenter) . Central Institute for Meteorology and Geodynamics (ZAMG) - and . ARC Systems Research GmbH itself, who is leading the project. Two regional climate models (RCMs) are used: the French ALADIN and the U.S. American MM5. (Both models are well established in regional weather prediction but not extensively tested in long term climate modelling). RCMs work similar to GCMs by applying fundamental physical equations and parameterisations describing the state and dynamics of the atmosphere and on a grid mesh. GCM results are input for RCMs with a finer grid resolving spatial details such as topography and land use, generating information on a higher spatial resolution which is physically consistent with the large-scale features. The GCM lattice information is transferred to the RCM lattice as lateral boundary condition. The interaction between GCM and RCM is (as usual) realised one-way with no feed back-loop from RCM to GCM. "Nesting" RCM lattice into the lower GCM resolution leads to horizontal resolutions at least an order of magnitude finer as GCMs. Multiple nesting can increase the spatial resolution - which is here conducted