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The mesoscale meteorological models Meso-NH and AROME

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

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The mesoscale meteorological models Meso-NH and AROME

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

  2. Outlook • Introduction : General consideration on meteorological predictions • Overview of meso-scale models • Meso-NH : From meso-scales to Large Eddy Simulations. • 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 1990’s 2000’s

  8. A research model, jointly developped by Meteo-France and Laboratoire d’Aérologie (CNRS/UPS) 40 users laboratories Meso-NH model 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 = 3500 s Horizontal wind Previous advection schemes 2D test case of orographic trapped waves t = 5000 s Horizontal wind Vertical velocity New advection schemes Turbulent Kinetic Energy Cloud A typical situation for optical turbulence T.Maric

  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 at 12h LES simulation LES Simulations 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 g/kg rv’ P3 aircraft qv’ at 0.5zi KA aircraft LES CONVECTIVE BOUNDARY LAYER with LES Water vapor variability - Couvreux et al. (2005) S(qv)<0 . .max(pdf) _ min(pdf) Dx=Dy= 100m, Dz<50m, Dt=7h

  13. LES simulation of an observed LLJ during the Sables98 campaign Objective: study the mixing processes across the maximum of the wind of an observed Low-Level Jet (LLJ) using LES • x = 6 m, y = 4 m, z = 2m (0 <z<100 m) and stretched above (z = 5 m at about 400 m) 100m tower • Night: 20-21 September 1998 Duero river basin 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 • 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 M.A. Jiménez Universitat de les Illes Balears

  15. STABLE BOUNDARY LAYER : Comparison MesoNH/MM5 at meso-scale 4H 23H x = 1km, zmin = 3m, 86 lev. 23H 4H Obs. A strongly stable night MM5 Meso-NH 4H 23H 23H 4H Bravo et al., 2008

  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. Zi = 1600m Forest : high sensible heat flux Zi = 900m Agricultural area : low sensible heat flux Atmospheric CO2 modelling : May – 27 2005 Boundary layer heterogeneity Sarrat et al.(2007a)

  19. 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, q, TKE • T2m becomes pronostic

  20. 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

  21. ALADIN Dx=10km AROME Dx=2,5km Vertical levels = 40, Time step=60s Forecast range = 36h (1800s on 64 processors) 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)

  22. Diurnal convection (2) Obs radar

  23. Cloudiness Total cloudiness AROME 12 h vs Sat Vis

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

  25. Conclusion Meso-NH • A well-known research model with a broad range of resolution. Largely validated by the community. Large variety of applications for the Boundary layer. • Used for Optical Turbulence (Masciadri et al.) : CN²=f (TKE, dq/dz) AROME • Will be operational next month • Includes Meso-NH physics, a mesoscale data assimilation. Competitive computational time. • Perspective for Optical Turbulence : climatology, prediction…

  26. Thank you for your attention

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