• Use NOAA14 TOVS radiances (120km data) in ARPEGE assimilation .
• New global wave model with a 1° mesh and assimilation of ERS altimeter data
• New seasonal forecast using ARPEGE-Climat model

2. Hardware used

• Information commutators on GTS are the TRANSMET computers (2 Sun Entreprise 3000, operating with OS Unix and RDBMS Oracle).
• The management of the forecasting system (control of the data in input of NWP models, postprocessing, production of charts with the NWP output) is made on a HP T600 computer running Oracle RDBMS, US-Navy originating NEONS meteorological datamanagement system, and PV-WAVE graphical software; one HP D370 is used as file server, one HP C180 workstation is devoted to the system monitoring, which is based on DCE. The whole system (production machine + file server + monitoring workstation), calledDIAPASON, is doubled for backup.
• NWP operational models are running on a FUJITSU VPP700E (26 processors with 2 Gbytes memory each)
• Dissemination of forecast and observation products (from GTS included), in particular to the french weather stations, is made through the Eutelsat communication satellite (RETIM system).

Average number of messages, by day:

GRID from BRACKNELL : 1500
GRID from WASHINGTON : 400
GRIB aero 1.25 from BRACKNELL : 1680
GRIB 2.5 from BRACKNELL : 3030
GRIB ECMF : 288

Fac-simile products:

• aeronautical charts from Bracknell (T4 code)

• Cifax charts on almost all links

Automated.

GTS data are controlled at several levels:

• transmission
• syntaxic coherence
• rudimentary control of likelihood: e.g. a sea level pressure value must be above 880 hPa and below 1080 hPa
• data control by comparison to adjacent (in time and/or space) data, or to different types of data at the same location: e.g. Td T is checked; In the same manner, a sudden slope breaking of in a temperature profile from a radiosonde far from thetropopause leads to the invalidation of the data.

Data to be reemitted on GTS are not modified.

All the observations that are used by the NWP system (SYNOP, SHIP, BUOY, SATOB, TOVS120, TEMP, PILOT, AIREP, AMDAR, ACARS) are controlled by comparison to the analyses and first guesses of the ARPEGE assimilationcycle: statistics are produced every month and summarized in a monthly bulletin.

The operational forecast system at Météo-France is based on two different numerical applications of the same code and an additional code to build the limited area model.

The ARPEGE-IFS library developed jointly by Météo-France and ECMWF (ARPEGE being the usual name in Toulouse and IFS the one used in Reading):

• ECMWF model for medium range forecasts (4-5 days)
• a variable mesh version run in Toulouse for short range predictions (1-4 days)

The ALADIN library developed jointly by Météo-France and the national meteorological or hydrometeorological services of the following countries: Austria, Belgium, Bulgaria, Croatia, Czech Republic,Hungary, Moldova, Morocco, Poland, Portugal, Romania, Slovakia, Slovenia.

7.1. Schedule of the Forecast System

The operational forecast system at Météo-France is based on ARPEGE/ALADIN runs using the observed data at 00 UTC and at 12 UTC:

• 00 UTC data: 1h50 cut-off, ARPEGE analysis and forecast up to 96h and ALADIN up to 36h

• 12UTC data: 1h50 cut-off, ARPEGE analysis and forecast up to 72h and ALADIN up to 36h

assimilation cut-off

availability

initialysed analysis (P0) cut-off+30'

ARPEGE forecast 20' every 24H range until 96H (morning end at 0340 UTC)

      " 72H (afternoon end at 1520 UTC)

ALADIN-France ARPEGE+10'                 until 48H (morning end at 0300 UTC)

                                             "         36H (afternoon end at 1500 UTC)

7.2. Medium range (4-10 days) forecast system

As mentioned above, it is the operational T319 model of ECMWF and T159 Ensemble Prediction System for 4-5day and 6-7day forecast bulletins.

7.3. Short range forecast system

The ARPEGE system(0-96 hours)

ARPEGE-IFS is a common Météo-France / ECMWF development. ARPEGE is the french name (Action de Recherche Petite Echelle Grande Echelle) while IFS is the name used at Reading (Integrated Forecast System).It is a tunable system based on a global spectral model which can be used for several applications: data assimilation, short-range prediction, medium-range prediction, climate research, predictability studies.

ARPEGE-IFS uses Schmidt's transformation leading to variable mesh configurations, having a pole of maximum resolution and a resolution varying continuously from that pole to the antipode (Courtier and Geleyn 1988). T being the nominal truncationand C the "stretching factor", the local resolution of the model is T x C over the pole, and T / C at the antipode.

The present version is T199 C3.5 having its pole in France (46.5N,2.6E), leading to T696.5 over France (corresponding roughly to a horizontal resolution of 20 km) and T57 over New Zealand (corresponding roughly to a horizontal resolution of 200km).

The number of vertical levels is 31, with an increased density in the low atmosphere. The first level is at 5 hPa.

Assimilation, objective analysis and initialization

The assimilation runs with a 6 hour cycle, with 10h45 cutoff for 00 and 12, and 5H30 cutoff for 06 and 18. The objective analysis is performed with an incremental 3D variational scheme : i.e. the departure obs-guessis computed at full resolution (T199C3.5) whereas the analyzed structures are produced at "low" resolution (T127C1.0). It is therefore assumed that the small scales (not analyzed) are forced by the (analyzed) large scales in the subsequent forecast.

The analysis works in vorticity, unbalanced divergence/ temperature/surface pressure and specific humidity on model levels.

assimilated data:	TEMP and TEMPSHIP (part A, B, C and D), PILOT (part A, B, C and D), AIREP, AMDAR, ACARS, SATOB, TOVS120km with observation time in [H-3h,H+3h] for the analysis at H,SYNOP, SHIP, BUOY, BATHY with observation time in [H-30',H+30'].
assimilation cycle:	6 hour cycle.
analysis method:	Multivariate three dimensional variational analysis
analysed variables:	Wind, temperature, surface pressure and specific humidity on model levels.
first guess:	A 6-hour forecast of ARPEGE. By default a 12, 18 or 24-hour forecast.
cover:	Global cover.
horizontal resolution:	Semi-linear grid (160 x320 points) associated with T127C1 truncation and equivalent to T105 Gaussian grid
vertical resolution:	The analysis is done on the model levels (see below): 31 levels (hybrid vertical co-ordinate) from screen up to 5 hPa.
initialization:	Incremental digital filter initialization (ie filtering analysis increments fields) using a Dolph-Chebishev filter with a stop-band edge period of 5h and a backward-forwardscheme.
surface:	analysis of superficial and mean soil temperature (resp moisture) from forecast errors on 2m temperature (resp. relative humidity) small relaxation towards climatology for snow and mean soil temperature and moisture

 

Model

basis equations:	Primitive equation system
independant variables:	Both components of the horizontal wind, temperature, specific humidity and surface pressure
dependant variables:	Vertical velocity and density
numerical technique:	Spectral 2TL semi-lagrangian model and temporal discretization using leap-frog semi-implicit scheme (see
integration domain:	The whole earth (global model).
orography, gravity wave drag:	The orography of this model is computed on the T199 C3.5 Gauss grid (300x600 points) from GLOB95 30"+US NAVY 10' + NOAA 5' data using a variational technique that strongly reduces the noise associated to Gibbswaves (see Bouteloup 1995). The gravity wave drag takes in account some anisotropy, blocking and mid-tropospheric effects.
horizontal diffusion:	Implicit in spectral space and incorporating an orography dependent correction for temperature
vertical diffusion:	Scheme linked to PBL (see next point)
planetary boundary layer:	ECMWF method (Louis et al. 1981)
resolution, time step:	This version of the ARPEGE model has a triangular truncature T199 with a stretching factor C3.5. The resolution varies from T 696.5 over France (15 km equivalent mesh for a finite difference model) to T57 over NewZealand (200 km equivalent mesh); it has 31 vertical levels from screen up to 5hPa, using the hybrid (s,p) co-ordinate from Simmons and Burridge (1981). The time step is 900 seconds.
earth surface:	Fixed analyzed sea surface temperature and amount of sea -ice. An improved version of the ISBA (Interaction Soil Biosphere Atmosphere) scheme is used, including an explicit parameterization of soil freezing. Six prognosticvariables are handled by ISBA: surface temperature, mean soil temperature, interception water content (water on the leaves), superficial soil water content (first centimeter), total liquid soil water content, total frozen soil water content. A very simpleparameterization of snow cover is added. Soil characteristics (texture, depth) are point-dependent. Vegetation characteristics are point- and month-dependent.
radiation:	Hypersimplified scheme at every time step (Ritter and Geleyn 1992)
convection:	Mass flux scheme (Bougeault 1985) modified by Ivanovici and Geleyn.
humidity:	Specific humidity is the variable: no storage of condensate; evaporation of falling rain; treatment of the ice-phase.

 

ALADIN (0-48hours)

ALADIN is a limited area version of ARPEGE-IFS. This implies that:

• ALADIN is spectral (like ARPEGE-IFS)

• As spectral-LAM it works on a biperiodic domain and uses bi-Fourier horizontal transforms

• Its physics and ARPEGE's one are identical

• It gets initial and lateral boundary conditions from ARPEGE

Up to now ALADIN is run in pure dynamical adaptation mode, i.e. without own data assimilation. The operational version is semi-lagrangian (usual time step 469.566s), with elliptic truncation E95x95 on Lambert projection domain (54°95N/33°66S,-11°18W/19°64E), leading to an equivalent resolution of roughly 7.5km.

The vertical resolution is 31 levels, the same as operational ARPEGE ones. The digital filter initialization uses a Dolph-Chebishev filter with a stop-band edge period of 3h and a backward-forward scheme.

NWP Products

The above described numerical models feed a analysis and forecast database, having following characteristics:

• different horizontal domains for different horizontal resolution (from the global domain with a 2.5° and 1.5° mesh to the "France" domain with a 0.1° mesh)
• vertical levels are the standard pressure levels
• independence, from the creating model, of the format of the database products.

The meteorological fields stored in this database are:

• at all levels: geopotential, temperature, humidity, wind (including vertical velocity)
• at screen level: pressure, temperature, humidity, heat and radiation fluxes, snow and water content
• at sea surface level: reduced pressure
• some data at particular levels: 500 hPa absolute vorticity, high medium and low cloudness, iso 0° and iso -10°, tropopause etc...

ARPEGE produces boundary conditions for the ALADIN applications run by LACE in Pragues, in Morocco, Romania, Poland, Portugal, while ALADIN-France provides boundary conditions for ALADIN-Belgique.

Operational use of NWP products

On screen (especially SYNERGIE workstation and Meteotel-PC software) or on paper, hundreds of charts...

7.4. Specialized forecasts

7.6. Long range forecasts (3 months)

A specific version of ARPEGE model , called ARPEGE-Climat is used 3 times a month to run 125 days forecasts, starting from ARPEGE assimilation. The seasonal is using mainly the same ARPEGE software as shortrange forecast model, except the following points:

resolution, time step:	This version of the ARPEGE model has a triangular truncature T63 without stretching. The collocation grid has 128x64 points with a reduction near the poles; ithas 31 vertical levels like IFS model during ERA-15 ECMWF reanalysis. The time step is 1800 seconds.
radiation:	Fouquart Morcrette scheme (1995)
clouds, vertical diffusion, stratified precipitations:	Ricard Royer statistical scheme (1993).

Scores of the operational ARPEGE model:

NH : Northern Hemisphere SH : Southern Hemisphere TR : Tropics

 

Against observations

24 hours

72 hours

Météo-France
SCEM/PREVI/COMPAS
42, av. Coriolis
F-31057 TOULOUSE Cedex 1
FRANCE

• use of more satellite data: ERS2 winds, SSM/I sea-ice index.
• new scheduling for operational suite with two more runs at 06 and 18 UTC
• 4DVAR assimilation
• 41 levels for ARPEGE/ALADIN models

Bougeault P., 1985 : "Parameterization of cumulus convection for Gate. A diagnostic and semi-prognostic study". Mon. Wea. Rev., 113, 2108-2121.

Bouteloup Y., 1995: "Improvement of the spectral representation of the earth topography with a variational method", Mon. Wea. Rev., 123, 1560-1573

Courtier, P. and J.F. Geleyn, 1988 :"A global numerical weather prediction model with variable resolution: application to the shallow-water equations"". Quart. J. Roy. Meteor. Soc., 1114, 1321-1346.

Giard, D., and E. Bazile, 1999 : Implementation of a new assimilation scheme for soil and surface variables in a global NWP model, submitted to Mon. Wea. Rev..

Louis J.F., 1979: "A parametric model of vertical eddy fluxes in the atmosphere", Bound. Lay. Met., 17, 187-202

Lynch, P., D. Giard and V. Ivanovici, 1997 : Improving the efficiency of a digital filtering scheme for diabatic initialization, Mon. Wea. Rev., 125, 1976-1982

Louis J.F., M. Tiedtke and J.F. Geleyn, 1981 :"A short history of the PBL parameterization at ECMWF". ECMWF Workshop on PBL parameterization, ECMWF, Reading, UK, 59-80.

Morcrette, J.-J., and Y. Fouquart, 1985: On systematic errors in parametrized calculations of longwave radiation transfer. Quart. J. Roy. Meteor. Soc., 111, 691-708.

Noilhan, J., and S. Planton, 1989 : A simple parameterization of land-surface processes for meteorological models, Mon. Wea. Rev., 117, 536-549

Piedelievre J.P., L. Musson-Genon and F. Bompay, 1990: MEDIA - An Eulerian model of atmospheric dispersion: first validation on the Chernobyl release, Jour. of Appl. Met., vol. 29, N° 12, 1205-1220

Ricard, J.-L., and J.-F. Royer, 1993: A statistical cloud scheme for use in an AGCM. Ann. Geophys. 11, 1095-1115

Ritter B. and J.F. Geleyn, 1992 : "A comprehensive radiation scheme for numerical weather prediction models with potential applications in climate simulations". Mon. Wea. Rev., 120, 303-325.

Simmons A.J. and D.M. Burridge, 1981 : "An energy and angular momentum conserving vertical finite difference scheme on a hybrid vertical coordinate". Mon. Wea. Rev., 109, 758-766.

Yessad K. and P. Bénard, 1996 :"Introduction of a local mapping factor in the spctral part of the Météo_france global variable mesh numerical model". Quart. J. Roy. Meteor. Soc., 122, 1701-1719.