1. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L Regional climate modelling in Belgium with the Regional Climate Model MAR Emilie Vanvyve – 1st year PhD student Pr. J.-P. van Ypersele (adviser, UCL-ASTR, Belgium) Dr H. Gallée (co-adviser, LGGE, France) Université catholique de Louvain (Louvain-la-Neuve, Belgium) Institute of astronomy and geophysics Georges Lemaître 26 May – 6 June 2003 Workshop on the Theory and Use of Regional Climate Models

2. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L Contents 1.Motivations... Future climate in Belgium ?  Thesis subject & plan 2.The MAR model 3.Current simulations : December 1993, a very wet month … Some results 4.Conclusion & next steps

3. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L 1. Climate change... Future climate in Belgium ? MORE intense precipitation events (IPCC, WGI) –1950-2000 : observed changes : likely (66-90%), over many Northern Hemisphere mid- to high latitude land areas –2000-2100 : projected changes : very likely (90-99%), over most areas Floods in Belgium –in winter (long rainfall) : too much rain on a too long time –in summer (storms) : too much rain on a too short time Thesis subject Study of the global warming impacts on the extreme precipitation regime over Belgium for the 21st century with a RCM : Modèle Atmosphérique Régional

4. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L Validation of MAR for simulating intense precipitation events in present climate –Winter 1993, winter 1995, summer 2002 Climate change study –Reference simulation : 10 years in actual climate –Climate change simulation : middle 21st century 1. Climate change... Future climate in Belgium ? Phys. disaggregator of precip. Hydrological model Hydro-meteo coupling MAR Re-analyses (ECMWF) MAR output GCM (LMDz)

5. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L 2. The MAR model (Gallée & Schayes, 1994) Some features –Limited-area model (grid-point, primitive equations) –Hydrostatic (non-hydrostatic in development) –  levels, cartesian horizontal coordinates (1 to 50 km-resolution), 0 to 3D –Initial and boundary conditions : ECMWF, GCM output, MAR output, observations, … –Surface submodel : Deardorff (1978), SISVAT (Soil/Ice Snow Vegetation Atmosphere Transfer scheme) Used in France (LGGE, LTHE, LMD), Belgium (ASTR-UCL), Benin, Ivory Coast Over : –Polar regions (Antarctica, Greenland) : mass balance –Africa (Western Africa) : hydrology, synoptic, stochastic disaggregation, interannual variability, convection –Europe : physical disaggregation in the Alpes, intense (precipitation) events, GCM coupling

6. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L Period December 1993 Domain 4320x4320 km Resolution 40 km Time step 120 s Initialisation re-analysis (ECMWF) Boundary forcing re-analysis (ECMWF), every 6 hours Other Deardorff (surface submodel) Fritsch-Chappell (convective adjustment) 3. Current simulations : December 1993, a very wet month … MAR setup « Belgium » MAR domain (108x108x40)

7. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L 3. Current simulations : December 1993, a very wet month … Sea-level pressure (daily mean) in « Belgium » Royal Meteorological Institute (Brussels) observations : Whole month characterized by successive low pressure systems from the 7th December, leading to an extreme rainy weather and serious floods in the southern Belgium.       MAR RE-ANALYSIS Temperature at 750 hPa (daily mean) in « Belgium »

8. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L 3. Current simulations : December 1993, a very wet month … Effect of domain size on the monthly precipitation amount smallestmedium largest

9. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L 3. Current simulations : December 1993, a very wet month … Effect of domain size on the monthly precipitation amount in « Belgium » smallest domain medium domainlargest domain

10. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L 3. Current simulations : December 1993, a very wet month … Monthly precipitation amount (largest domain) MAR GPCC « Belgium » Total Snowfall Non-convective Convective

11. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L 3. Current simulations : December 1993, a very wet month … Daily/monthly precipitation in Belgium RMI observations : maxima between 20 and 70 mm/day observed on the 12th, 19th, 20th and 30th MAR simulated precipitation = 65% of observed precipitations    

12. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L Conclusion & next steps Daily values of temperature, pressure agree with observations Daily and spatial distribution of precipitation agrees with observations But precipitation amount is underestimated by ± 35%. Possible error sources : –Coarse definition of sub-domain « Belgium » –MAR resolution too low –ECMWF fields : enough water ? –Model physics well parameterized/adapted to the situation ?  December 1993 meteorological situation over Belgium is well simulated by MAR. Go on with the validation of winter 1993, …

13. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L

14. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L 2. The MAR model Limited-area model (grid-point, primitive equations) [Gallée & Schayes, 1994, UCL-ASTR] DYNAMICS Hydrostatic (non-hydrostatic in development) Grid  normalized pression (upto 60 levels) Cartesian horizontal coordinates 1 to 50 km-resolution 0D (ground) to 3D Initial and boundary conditions ECMWF re-analysis, GCM (LMDz), … observations (necessary pre-processing) MAR outputPHYSICS Radiative transfers : Solar (Fouquart & Bonnel, 1980), Infrared (Morcrette, 1984) Turbulence closures : 1.5 order (Therry & Lacarrère, 1982), K-e (Duynkerke, 1980) Convective adjustement : Bechtold (2000), Fritsch & Chappell (1980) + Brasseur (1999), Kain & Fritsch (1990) Microphysics (Kessler, 1969) Surface layer fluxes (Businger, 1973) Surface submodel : Deardorff (1978), SISVAT (Soil/Ice Snow Vegetation Atmosphere Transfer Scheme) SST (ERA-15, Reynolds SST, …)

15. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L 2. The MAR model LGGE (France) [H. Gallée] –Polar regions (Antarctica) : mass balance ASTR (Belgium) [J.-P. van Ypersele](  Yvory Coast) –Polar regions (Greenland) : mass balance –Europe : intense precipitation events LTHE (France)(  Benin) –Africa (Western Africa) : hydrology, synoptic, stochastic disaggregation, interannual variability, convection –Europe (Alpes) : physical disaggregation LMD (France) –Europe : GCM coupling

16. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L Southern part of the domain : cold bias Cold bias linked to a pressure positive bias T MAR (600 hPa) – T ECMWF (600 hPa)Sea-level P MAR – Seal-level P ECMWF

17. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L Climate change in Belgium ? MORE intense precipitation events (IPCC, WGI) Confidence in observed changes (1950-2000) : likely (66-90%), over many Northern Hemisphere mid- to high latitude land areas Confidence in projected changes (2000-2100) : very likely (90-99%), over most areas Precipitation and temperature changes versus reference period 1969-1990 Belgium (IS92a scenario) 2010-39 2040-69 2070-99 Winter

18. ASTR Institute of astronomy and geophysics G. Lemaître –– Université catholique de Louvain U C L LMD LMD (Paris, France) EUROPE EUROPE with P. Marbaix (BIOCLIM) GCM coupling ASTR (UCL, Belgium) J.-P. VAN YPERSELE POLARGreenland) POLAR (Greenland) with X. Fettweis (mass balance) EUROPE (& Belgium) EUROPE (& Belgium) with E. Vanvyve (climate change, intense precipitation events) the MAR team MARMAR LGGE LGGE (Grenoble, France) POLAR (Antarctic) POLAR (Antarctic) with H. GALLEE (conception, mass balance) (VIDAS, ATHENA, RIME) Continental ice Africa – hydrology Polar Benin Ivory Coast LTHE LTHE (Grenoble, France) AFRICA (Sahel) continental water Hydrological coupling Synoptic Stochastic disaggregation Interannual variability Convection EUROPE (Alpes) Physical disaggregation