Update on model developments: Meteo-France Update on model developments: Meteo-France NWP model / clouds and turbulenceNWP model / clouds and turbulence
CLOUDNET workshop / Paris 27-28/05/2002
Jean-Marcel PiriouCentre National de Recherches MétéorologiquesGroupe de Modélisation pour l’Assimilation et la Prévision
Summary
• How may 1D studies improve 3D models? Example of the How may 1D studies improve 3D models? Example of the
EUROCS project, links with CLOUDNETEUROCS project, links with CLOUDNET
• Clouds and turbulence: present developments and Clouds and turbulence: present developments and
perspectives of the ARPEGE/ALADIN NWP modelperspectives of the ARPEGE/ALADIN NWP model
PHYSICS
Global ARPEGEAquaplanet mode
SCM ARPEGE (EUROCS, GATE, TOGA,BOMEX, ARM, …)
LAM ALADIN / coupled / 10 km
Global stretched ARPEGE / 4DVAR-ass. / 20 to 200 km
Global regular ARPEGE / 4DVAR-ass. / 100 km
ARPEGE NWP ModelARPEGE NWP ModelJ.M. Piriou 2002J.M. Piriou 2002
IFS NWP ModelIFS NWP ModelBeljaars 2002Beljaars 2002
ObservationsObservationsYang and Slingo MWR 2001Yang and Slingo MWR 2001
Unified Climate ModelUnified Climate ModelYang and Slingo MWR 2001Yang and Slingo MWR 2001
Diurnal cycleof convection /
JJA
GCM picture from Colostate web page
Bring together a community of modelers : hierarchy of scales
LES & CRMs --- SCMs --- RCMs & GCMsobs obs
LES: Large Eddy SimulationCRM: Cloud Resolving ModelSCM: Single Column ModelRCM: Regional Climate ModelGCM: General Circulation Model
EUROCS : EUROpean Cloud Systems
Final aims: to improve the treatment of cloud systems in global and regional climate models
Links with GCSS (GEWEX Cloud System Study)
3-year project funded by theEuropean Union (Mar 2000 – Feb2003)
Concentrates on 4 major well identified deficiencies of climate models: stratocumulus over oceandiurnal cycle of shallow cumulus sensitivity of deep convection to mid-atmosphere humiditydiurnal cycle of deep convection over land
for more infos: www.cnrm.meteo.fr/gcss/EUROCS/EUROCS.html & J.-L. Redelsperger
z=
70m
to 6
00m
x= y= 1km
clouds
Diurnal cycle of deep convection(Françoise Guichard, Météo-France)
COMMON CRMs/SCMs CASE STUDY
Southern Great Plains
GCSS WG4 Case3a
4-day runs with deep convection occuringlarge-scale advections prescribed from observationsfixed surface heat fluxeswind nudged towards observedcyclic lateral boundary conditions
case part of the GCSS intercomparaison exercise for CRMs Xu et al. (2002) & SCMs (Xie et al. 2002)
ARM : Atmospheric Radiation measurement
1 : an « observed case » to assess our models over land (GCSS/ARM)
2 : building an « idealized case » to address the diurnal cycle of deep convection over land and its representation in models
THE IDEALIZED CASE
same framework of previous case except: 27 Mai 1997 of GCSS case 3 repeated twice large-scale vert. adv. (relatively weak) & prescribed surf. fluxes 48 h run, begins in the morning instead of the evening
rainfall events tend to occurs earlier in SCMs than CRMs (2 SCMs missing) + similar findings (e.g., noise & no or weak downdraughts)
results still preliminary, work in progress
before the development of deep convection
THE IDEALIZED CASE: transition regimes
(m)
SCMCRM runs
MAX CLOUD TOP HEIGHT
a « shallow » non-precipitating transition period which last a
few hours in CRMs
Lx: 300 km
15 km
snapshots of cloud + rain water content in CRM run
transition phase: not represented in several SCMs
THE IDEALIZED CASE : CIN
almost no CIN in SCM runs during daytime (true for at least 4 SCMs) ! apparently not simply a resolution problem
challenging for CRMs too strongly modulated by convective activity in CRMs runs, deep convection increases the CIN possibly related to convective downdraughts (?)
deep convection often occurs earlier than observed in SCMs runs toono succession of dry-shallow-deep regimes in SCMs, dry to deep directlycomplex sensitivity to triggering criteria & downdraughts formulationno CIN during daytime & weak downdraughts ( a link?)
CONCLUSIONS from diurnal cycle of deep convection case
Diurnal cycle of shallow cumulus
(Geert Lenderink, KNMI)
EUROCS: Marine stratocumulus case
(Peter Duynkerke, IMAU)
EUROCS marine stratocumulus caseEUROCS marine stratocumulus case
Perspectives for the ARPEGE/ALADIN physics
• March towards new prognostic cloud and turbulence March towards new prognostic cloud and turbulence
variables: ql/i, qr/s, TKE, w_ud, w_ddvariables: ql/i, qr/s, TKE, w_ud, w_dd
• EUROCS: 4 validation cases EUROCS: 4 validation cases (next 12 months)(next 12 months)
• CLOUDNET: colocated ql/i, qr/s, PBL depth, cloudiness, CLOUDNET: colocated ql/i, qr/s, PBL depth, cloudiness,
close TEMP data to provide in-situ validation of new close TEMP data to provide in-situ validation of new
microphysics / turbulence microphysics / turbulence (in some months?)(in some months?)
Conclusions / perspectives
• During the last years 1D studies have become more and During the last years 1D studies have become more and
more important to develop and validate 3D models physical more important to develop and validate 3D models physical
packagespackages
• Both EUROCS (well posed lateral conditions) and Both EUROCS (well posed lateral conditions) and
CLOUDNET (long time series) will be used as a test-bed for CLOUDNET (long time series) will be used as a test-bed for
the new cloud physics and turbulencethe new cloud physics and turbulence