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Status of AROME Physics

Status of AROME Physics. Sylvie Malardel Yann Seity, Gwenaëlle Hello, Christine Lac, Valery Masson, Patrick Lemoigne et al Météo-France/CNRM et Laboratoire d’aérologie. AROME. Aladin dynamical core. AROME Physics.

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Status of AROME Physics

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  1. Status of AROME Physics Sylvie Malardel Yann Seity, Gwenaëlle Hello, Christine Lac, Valery Masson, Patrick Lemoigne et al Météo-France/CNRM et Laboratoire d’aérologie

  2. AROME Aladin dynamical core

  3. AROMEPhysics • Current ECMWF radiation scheme called every 15 min (F.M. for SW and RRTM for LW) • Microphysics (vapor+5 hydrometeors) • Turbulence (CBR, pronostic TKE) • Shallow convection (KFB) • + a subgrid representation of clouds • Externalised surface • Isba • Simple schemes for sea and lakes • TEB

  4. The Daily Arome prototype MIDPYR since june 2005, SUDE since september 2005 Replaced by NORE this winter (plots on ALADIN2 WebSite) This Arome is running every day on different domains

  5. PARI BRET NORE MIDPYR SUDE AROME domains over FRANCE

  6. Deep Clouds Microphysics Coupling with the dynamics

  7. An AROME good forecast : 21 June 2005

  8. 21 TU 24 TU 18 TU 12 TU 15 TU 21 June 2005 Case Inst. AROME rainfalls L41 AROME wind

  9. 21 June 2005 Case 15 TU AROME coupled with Aladin 3DVAR AROME coupled with Aladin oper

  10. Simulation (Meso-NH) Deep clouds graupel Z > 60 dBz Microphysical retrievals : IOP 2A (intense convection) 12 km (x) hail + graupel (o) hail ( ) rain (x) hail + graupel (o) hail ( ) rain 100 km Tabary, 2002

  11. Deep clouds snow hail + graupel rain Meso-NH simulation Microphysical retrievals : IOP 3 (moderate convection) 18:10 UT dry snow hail + graupel rain 18:30 UT Pujol et al., 2005

  12. Deep clouds MESO-NH, x=2.5km m MESO-NH, x=2.5km max : 99 mm Initialisation Ducrocq et al (2000)’s max: 31 mm Quasi-stationnary MCS 13-14 Oct. 1995 MESO-NH, x=10km OBSERVATIONS m mm max : 25 mm max : 135 mm Initial conditions: ARPEGE analysis at 18UTC Cumulated precipitation 01 UTC to 06 UTC the 14th Oct. 1995 (Ducrocq et al, 2002)

  13. Deep clouds • As Méso-NH, Arome is able to simulate correctly the organisation of mesoscale convective organisation • Sensitivity to coupling and initial condition For AROME in 2006 • Use diagnostics to evaluate more objectively and statisticaly precipitating events • Adaptation of numerical aspects of the sedimentation parametrization (time splitting) to longer time steps (> 60s)

  14. Fog (and low clouds) Microphysics Radiation Vertical resolution Turbulence in stable layers

  15. First case of Fog : 7 January 2005 AROME 2 last levels cloud cover 09 TU

  16. First case of Fog : 7 January 2005 AROME 2 last levels cloud cover 15 TU

  17. Fog just a few studies with Meso-NH … But A PRIORITY for AROME Bergot et al., 2005, submitted : Intercomparison of 1D numerical models for prediction of the fog ( mp, turbulence, Dz) 2 events at Paris-CdG. 4 sets of initial conditions (RS): 18UTC (onset), 21 (thickening), 00 (mature) and 03 (disspation)

  18. Cumulated liquid water content Fog Meso-NH without sedimentation of small droplets Crude test : Modification of the autoconversion threshold Meso-NH with sedimentation Late dissipation due to excessive rc : lack of gravitational settling Initialization at 03UTC Bergot et al., 2005, submitted

  19. Fog For AROME in 2006 • Microphysics : Implementation of the sedimentation for small droplets • Tests on the sensitivity to vertical resolution  Additional levels to L41 ? (Cobel-Isba with L41 shows degradation) • Evaluation on CAPITOUL and on several international airports. Run of AROME on Ile-de-France on winter 2005 and in 1D on Casablanca and Varsovie (to be confirmed)

  20. Convective boundary layersand stratocumulus Shallow convection Turbulence Subgrid clouds Microphysics Surface

  21. 2005/08/20 09 TU AROME Meso-NH with SUBGRID COND + SHALLOW30min : Adjustment time of 30min Meso-NH with SUBGRID COND + SHALLOW : Adjustment time of 3h in the closure Coupling with Aladin oper (r0)

  22. Bomex : LES

  23. ARM : LES

  24. ARM : cloud mixing ratio LES

  25. BL clouds : Cu For AROME in 2006 • Modification of the KFB closure (w*, Grant et al, 1999) • Improvement of subgrid cloud representation (Bechtold et al, 1995, Lenderink and Siebesma, 2000) • Test of EDMF scheme in Meso-NH (P.Soares)

  26. LES x= y= 500m Cloud water mixing ratio 0h LT12hLT 0hLT 0h LT12hLT 0hLT x= y= 2.5km SCM Stratocumulus : What’s about the resolutions of AROME ? I.Sandu

  27. BL clouds : Sc x=500m,Dz=25m x=500m,Dz=50m x=500m,Dz=80m LES x=500m,Dz=10m Liquid Water Path I. Sandu

  28. BL clouds : Sc Preliminary tests in Meso-NH at the resolutions of AROME • Diurnal cycle of Sc is maintained at the resolution of Arome • LWC more sensitive to lower Dz than lower Dx • Main impact of Dz at the top of Sc (entrainment) than beneath For Arome , second part of 2006 • Sensitivity tests on vertical resolution for cloud-top entrainmentAdditional levels to L41? • Interest of an entrainment parametrization (Lock, 2001, 2004. ARPEGE-Climat).

  29. Dry CBL La Cape Sud : Comparison Meso-NH/RS of BL height (parcel method) between 6 and 17UTC Weak overestimation during the afternoon Weak underestimation during the morning Evaluation CARBOEUROPE Forecasts of Meso-NH (8km) in an operational mode during the experiment

  30. Dry CBL Eddy-diffusivity (local) : Too sharpe inversion due to lack of top-entrainment Too unstable  BUT limitations are well-known, inherent to Eddy-diffusivity • The K-diffusion doesn’t take into account countergradient. • Entrainment is not treated explicitly in the K-diffusion approach. • But diffusion remains necessary, for transition to neutral or stable BL.

  31. Dry CBL On L On the TOMs 2L with TOMs 2L 2L without TOMs 1L 1. Countergradient with Third order moments

  32. Dry CBL Under development in Meso-NH (2006-2008) • Improvement of EDMF scheme : entrainment, extension to momentum transport (In collaboration with P.Soares in 2006) • Parametrization of TOMs with an entraining plume used to find the mass-flux. • Improvement of the BL89 mixing length in the same way (V.Masson) For AROME in 2006 • TOMs on heat momentum fitted on LES already implemented in Meso-NH  evaluation of the impact for AROME on CBL (needs of evaluation on test cases, impact on unreal rolls ?) • EDMF scheme : evaluation of the impact in Meso-NH during the 1st sem.2006 (In collaboration with P.Soares) • Comparison EDMF/TOMS on the same cases

  33. Summary • An Arome daily prototype has been running for 6 months (without any blow up) • Some good forcasts and some less good (but only qualitative and episodic validation) • Some imperative improvement have to be done quickly on the physics before more serious validation • Shallow convection and subgrid clouds • Fog dissipation • Numerical improvement : SL sedimentation • Other preoccupations : Sc, Dry BL etc

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