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 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

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)

AROME domains over FRANCE MIDPYR SUDE NORE PARI BRET

Deep Clouds Microphysics Coupling with the dynamics

An AROME good forecast : 21 June 2005

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

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

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

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

Initialisation Ducrocq et al (2000)’s Deep clouds Quasi-stationnary MCS 13-14 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)

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)

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

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

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

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)

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

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)

Convective boundary layers and stratocumulus Shallow convection Turbulence Subgrid clouds Microphysics Surface

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)

Bomex : LES

ARM : LES

ARM : cloud mixing ratio LES

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)

Stratocumulus : What’s about the resolutions of AROME ? x= y= 2.5km SCM Cloud water mixing ratio 0h LT 12hLT 0hLT LES 0h LT 12hLT 0hLT x= y= 500m I.Sandu

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

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, 2004. ARPEGE-Climat).

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

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.

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

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 (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)

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