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

5. AROME domains over FRANCE
MIDPYR
SUDE
NORE
PARI
BRET

6. Deep Clouds
Microphysics
Coupling with the dynamics

7. An AROME good forecast : 21 June 2005

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

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

10. Microphysical retrievals : IOP 2A (intense convection)
Deep clouds
Microphysical retrievals : IOP 2A (intense convection)
graupel
Simulation (Meso-NH)
Z > 60 dBz
12 km
(x) hail + graupel
(o) hail
( ) rain
Un exemple de comparaison entre une restitution radar de paramètres microphysiques et une simulation numérique:
La simulation restitue correctement l’apparition de la grêle entre 18h et 19h et l’étagement des hydrométéores: mélange grêle/graupel, grêle, mélange pluie/grêle, et pluie. Les paramètres restitués par l’algorithme radar sont: les cristaux orientés verticalement (VC) et horizontalement (HC), la neige mouillée (WS) et sèche (DS), les mélange graupel/grêle (GH) et grêle/pluie (HR), la grêle (HL), et la pluie de différentes intensités (LR,MR,HR).
(x) hail + graupel
(o) hail
( ) rain
100 km
Tabary, 2002

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

12. Initialisation Ducrocq et al (2000)’s
Deep clouds
Quasi-stationnary MCS Oct. 1995
MESO-NH, x=10km
OBSERVATIONS
max: 31 mm
MESO-NH, x=2.5km m
MESO-NH, x=2.5km
Initialisation Ducrocq et al (2000)’s
max : 99 mm 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. just a few studies with Meso-NH … But A PRIORITY for AROME
Fog
just a few studies with Meso-NH …
But A PRIORITY for AROME
Scientist
Model
Levels
<50m
<200m
E.Terradellas
Hirlam-INM
(1D version used in Spain) 1 3
O. Liechti
tBM 2 7
N.W. Nielsen
Hirlam-DMI 13 20
T. Bergot
Cobel-Isba
M. Mueller
Cobel-Noah 18 30
J.Cuxart/A.Mira
MesoNH 50 89
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. Fog Cumulated liquid water content
Meso-NH without sedimentation of small droplets
Fog
Crude test : Modification of the autoconversion threshold
Late dissipation due to excessive rc : lack of gravitational settling
Meso-NH with sedimentation
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 layers and stratocumulus
Shallow convection
Turbulence
Subgrid clouds
Microphysics
Surface

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

22. Bomex :
LES

23. ARM :
LES

24. ARM : cloud mixing ratio
LES

25. BL clouds : Cu Modification of the KFB closure (w*, Grant et al, 1999)
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. Stratocumulus : What’s about the resolutions of AROME ?
x= y= 2.5km
SCM
Cloud water mixing ratio
0h LT hLT hLT
LES
0h LT hLT hLT
x= y= 500m
I.Sandu

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

28. For Arome , second part of 2006
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, ARPEGE-Climat).

29. Dry CBL Evaluation CARBOEUROPE
Forecasts of Meso-NH (8km) in an operational mode during the experiment
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

30. BUT limitations are well-known, inherent to Eddy-diffusivity
Dry CBL
BUT limitations are well-known, inherent to Eddy-diffusivity 
Too sharpe inversion due to lack of top-entrainment
Eddy-diffusivity (local) :
Too unstable
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. 1. Countergradient with Third order moments
Dry CBL
1. Countergradient with Third order moments
On L 1L 2L
On the TOMs
2L without TOMs
2L with TOMs

32. Under development in Meso-NH (2006-2008)
Dry CBL
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
Under development in Meso-NH ( )
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)

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