Formation

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Jean-Marcel Piriou Centre National de Recherches
Météorologiques Groupe de Modélisation pour
lAssimilation et la Prévision
Update on model developments Meteo-France NWP
model / clouds and turbulence
CLOUDNET Workshop / Utrecht 21-22/10/2002
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Global ARPEGE Aquaplanet mode
SCM ARPEGE (EUROCS, GATE, TOGA,BOMEX, ARM, )
Global regular ARPEGE / 4DVAR-ass. / 66 km
PHYSICS
LAM ALADIN / coupled / 10 km
Global stretched ARPEGE / 4DVAR-ass. / 20 to 200
km
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Present operational schemes Under progress
Radiation Geleyn and Hollingsworth (1979), Ritter and Geleyn (1992) More accurate infra-red exchanges between surface and layers
Grid-scale cloud scheme Diagnostic in ql/i, all supersaturation removed, liquid/ice condensation ? T, melting/ freezing/ evaporation/ Kessler (1979), Clough and Franks (1991) Prognostic ql/i, qr/s
Subgrid-scale cloud scheme (convection) mass-flux scheme, CISK-type closure and triggering, water vapour budget using a Kuo-type closure, downdrafts, momentum flux Modified trigger functions (TKE, CIN)
Turbulence 1st order closure scheme after Louis (1979), Louis and al. (1981), using a flux-gradient K-theory with Ri dependency, variable roughness lengths over sea (Charnock) PrognosticTKE scheme, mixing  Betts  conservative variables thetal and qt instead of theta and qv
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• Perspectives operational model (GCM 20-200km
  ARPEGE LAM 10km ALADIN)
• March towards new prognostic cloud and turbulence
  variables ql/i, qr/s, TKE, w_ud, w_dd
• EUROCS 3 transition cases (well posed lateral
  conditions to compare CRMs to GCMs or LAMs)
• Model to satellite, data assimilation cycle
• CLOUDNET (long time series, detailed profiles)
  colocated ql/i, qr/s, PBL depth, cloudiness,
  close TEMP data to provide in-situ validation of
  new microphysics / turbulence
• Perspectives 2 a CRM in operations around
  2008!...
• 2003 first tests of the existing CRM méso-NH
  physics in the ALADIN-NH 2.5km dynamical core ?
  need for validations within CLOUDNET?