1. The mesoscale meteorological models Meso-NH and AROME C.Lac (CNRM/GMME) For the Meso-NH community and the AROME team « Astronomy meets Meteorology », 15-18 September Parc Naturel VerdonMarseille 85ppb Nocturnal ozone in the residual layer over Marseille

2. Outlook 1.Introduction : General consideration on meteorological predictions 2.Overview of meso-scale models 3.Meso-NH : From meso-scales to Large Eddy Simulations. 4.The new operational meso-scale model AROME

3. Space and time scales Optical turbulence

4. On the importance of the resolution Prognostic variables of the model are mean variables on the grid box

5. Processes that need to be parametrized

6. What kind of models ? 2 2 -2 km (LES) Mesoscale models All these kinds of models need different level of parametrization - Climate models and Global weather prediction : All the physics parametrized - Mesoscale models : Convection (deep) resolved. - Large Eddy Simulation. The most energetic eddies in turbulence are resolved, but it still needs to parameterize small-scale turbulence, radiation, microphysics.

7. Mesoscale models ModelsMM5 PSU/NCAR RAMS Meso-NH MF/LA WRF NCAR/MMM LM COSMO UM UKMO AROME MF Min. Resolution LES 1km2.5km Up to 1km Spectral/ grid point Grid Spectral Advection scheme Euler. SL Temporal scheme Explicit LF Explicit Split SI Time stepFor 2.5km 8s (  t=3  x ) For 2.5km 6-8s For 2.5km 15s For 2.5km 60s Nesting2 way 1 way Turbulence scheme 1.5 closure 1D or 3D 1.5 closure 1D or 3D 1.5 closure 1D or 3D 2.5 closure 1D or 3D 2.5 closure 1D or 3D 1.5 closure 1D 1.5 closure 1D MicrophysicsUp to 6 species Data assimilation 1990’s2000’s

8. Meso-NH model 40 users laboratories A research model, jointly developped by Meteo-France and Laboratoire d’Aérologie (CNRS/UPS) http://mesonh.aero.obs-mip.fr/mesonh/ 1. Recent improvements in the dynamics 2. Focus on the turbulence. Importance of the surface coupling.

9. t = 5000 s Turbulent Kinetic Energy T.Maric 2D test case of orographic trapped waves Horizontal windVertical velocity Cloud New advection schemes Previous advection schemes t = 3500 s Horizontal wind A typical situation for optical turbulence

10. Diurnal cycle of boundary layer height Buoyancy effects

11. General principles of the turbulence scheme Closure : with, L=Mixing length Further details in E.Masciadri’s presentation >0 in convective <0 in stable

12. Lidar observations LES Simulations rv’rv’ LES simulation 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10. 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10. 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10. 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10. g/kg P3 aircraft KA aircraft.. max (pdf) _ min (pdf) LES qv’qv’ at 0.5z i CONVECTIVE BOUNDARY LAYER with LES Water vapor variability - Couvreux et al. (2005) at 12h  x=  y= 100m,  z<50m,  t=7h S(q v )<0

13. LES simulation of an observed LLJ during the Sables98 campaign  Night: 20-21 September 1998 100m tower Duero river basin  x = 6 m,  y = 4 m,  z = 2m (0 <z<100 m) and stretched above (  z = 5 m at about 400 m) Objective: study the mixing processes across the maximum of the wind of an observed Low-Level Jet (LLJ) using LES M.A. Jiménez Universitat de les Illes Balears STABLE BOUNDARY LAYER Difficulty to simulate due to local circulations (drainage flows), intermittent effects (gravity waves), low level jets (LLJ).

14. Results (I): Mean profiles M.A. Jiménez Universitat de les Illes Balears The maximum of the wind and the height are well captured The LLJ height coincides with the inversion height The surface temperature obtained from the LES cools down much more than the observations

15. A strongly stable night STABLE BOUNDARY LAYER : Comparison MesoNH/MM5 at meso-scale  x = 1km,  z min = 3m, 86 lev. Obs. MM5 Meso-NH Bravo et al., 2008 23H 4H 23H4H 23H 4H 23H4H MNHMM5 UBiasO.821.37 Rmse0.751.15 TBias1.690.31 Rmse2.031.41

16. On the importance of the surface coupling for the turbulence

17. The SURFEX (SURface Externalized) land surface scheme see P.Le Moigne’s presentation

18. Sarrat et al.(2007a) Atmospheric CO 2 modelling : May – 27 2005 Boundary layer heterogeneity Zi = 900m Agricultural area : low sensible heat flux Zi = 1600m Forest : high sensible heat flux

20. A recent improvement in SURFEX: the CANOPY scheme (Masson, 2008) 1D Surface Boundary Layer scheme, with 6 added levels between the first atmospheric level and the surface An added term for U, , q, TKE T2m becomes pronostic

21. AROME (Applications of Research to Operations at MesoscalE) Almost-current operational meso-scale system (2.5km) with data assimilation (P.Brousseau’s talk) -Dynamics : from ALADIN-NH - Physics : from Meso-NH

22. Objectives of AROME - Expected to improve heavy precipitation forecasts with strong emphasis on Mediterranean flash-floods - Prediction of local events (fog, breeze, urban effects, orographic) -Applications : chemistry, hydrology, fog, ocean, roads … - A complex data assimilation system (further details in P.Brousseau’s presentation) Vertical levels = 40, Time step=60s Forecast range = 36h (1800s on 64 processors) ALADIN  x=10km AROME  x=2,5km

23. Diurnal convection (2) Obs radar

24. Cloudiness Total cloudiness AROME 12 h vs Sat Vis

25. 2nd AROME training course, Lisbon, March 2008 25 Model performance : low-level scores  objective scores of AROME-France using French automatic surface obs network (hourly data every ~30km)‏ forecast range (h)‏ Scores over France on 3 months Nov07-Jan08 (Arome in pink) MSL pressure 10m windspeed 2m Temperature forecast range (h)‏ Rmse Aladin Rmse Arome Bias Arome Bias Aladin Rmse Aladin Rmse Arome Bias Arome Bias Aladin Rmse Aladin Rmse Arome Bias Arome Bias Aladin

26. Conclusion 1.A well-known research model with a broad range of resolution. Largely validated by the community. Large variety of applications for the Boundary layer. 2.Used for Optical Turbulence (Masciadri et al.) : C N ²=f (TKE, d  /dz) Meso-NH AROME 1.Will be operational next month 2.Includes Meso-NH physics, a mesoscale data assimilation. Competitive computational time. 3.Perspective for Optical Turbulence : climatology, prediction…

27. Thank you for your attention