An inter-comparison of regional climate models for Europe: model performance in present-day climate

Byline: Daniela Jacob (1), Lars Barring (5), Ole Bossing Christensen (2), Jens Hesselbjerg Christensen (2), Manuel Castro (11), Michel Deque (8), Filippo Giorgi (10), Stefan Hagemann (1), Martin Hirschi (3), Richard Jones (9), Erik Kjellstrom (5), Geert Lenderink (6), Burkhardt Rockel (7), Enrique Sanchez (11), Christoph Schar (3), Sonia I. Seneviratne (4), Samuel Somot (8), Aad Ulden (6), Bart Hurk (6) Abstract: The analysis of possible regional climate changes over Europe as simulated by 10 regional climate models within the context of PRUDENCE requires a careful investigation of possible systematic biases in the models. The purpose of this paper is to identify how the main model systematic biases vary across the different models. Two fundamental aspects of model validation are addressed here: the ability to simulate (1) the long-term (30 or 40 years) mean climate and (2) the inter-annual variability. The analysis concentrates on near-surface air temperature and precipitation over land and focuses mainly on winter and summer. In general, there is a warm bias with respect to the CRU data set in these extreme seasons and a tendency to cold biases in the transition seasons. In winter the typical spread (standard deviation) between the models is 1 K. During summer there is generally a better agreement between observed and simulated values of inter-annual variability although there is a relatively clear signal that the modeled temperature variability is larger than suggested by observations, while precipitation variability is closer to observations. The areas with warm (cold) bias in winter generally exhibit wet (dry) biases, whereas the relationship is the reverse during summer (though much less clear, coupling warm (cold) biases with dry (wet) ones). When comparing the RCMs with their driving GCM, they generally reproduce the large-scale circulation of the GCM though in some cases there are substantial differences between regional biases in surface temperature and precipitation. Author Affiliation: (1) Max Planck Institute for Meteorology, Bundesstr.53, 20146, Hamburg, Germany (2) Danish Meteorological Institute, Lyngbyvej 100, 2100, Copenhagen, Denmark (3) Institut for Atmospheric and Climate Science ETH, 8057, Zurich, Switzerland (4) Global Modeling and Assimilation Office NASA, Goddard Space Flight Center, Greenbelt, MD, USA (5) Rossby Centre, SMHI, 60176, Norrkoping, Sweden (6) Royal Netherlands Meteorological Institute, 3730 AE, de Bilt, The Netherlands (7) GKSS Forschungszentrum Geesthacht, Max-Planck-Strasse, 21502, Geesthacht, Germany (8) Meteo-France CNRM, 42 av. Gaspard Coriolis, 31057, Toulouse Cedex, France (9) Met Office Hadley Centre (Reading Unit), Meteorology Building, University of Reading, Reading, RG6 6BB, UK (10) The Abdus Salam International Centre for Theoretical Physics, P. O. BOX 586, 34100, Trieste, Italy (11) Facultad de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, Avda. Carlos III s/n, 45071, Toledo, Spain Article History: Registration Date: 17/11/2006 Received Date: 15/02/2005 Accepted Date: 17/10/2006 Online Date: 17/03/2007