Status of AROME Physics

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Status of AROME Physics

• Sylvie Malardel
• Yann Seity, Gwenaëlle Hello, Christine Lac,
  Valery Masson, Patrick Lemoigne et al
• Météo-France/CNRM et Laboratoire daérologie

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AROME
Aladin dynamical core
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AROME Physics

• Current ECMWF radiation scheme called every 15
  min (F.M. for SW and RRTM for LW)
• Microphysics (vapor5 hydrometeors)
• Turbulence (CBR, pronostic TKE)
• Shallow convection (KFB)
• a subgrid representation of clouds
• Externalised surface
• Isba
• Simple schemes for sea and lakes
• TEB

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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)

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AROME domains over FRANCE
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Deep Clouds

• Microphysics
• Coupling with the dynamics

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An AROME good forecast 21 June 2005
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21 June 2005 Case
Inst. AROME rainfalls
L41 AROME wind
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21 June 2005 Case
15 TU
AROME coupled with Aladin 3DVAR
AROME coupled with Aladin oper
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Microphysical retrievals IOP 2A (intense
convection)
12 km
(x) hail graupel
(o) hail
( ) rain
(x) hail graupel
(o) hail
( ) rain
100 km
Tabary, 2002
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Microphysical retrievals IOP 3 (moderate
convection)
1810 UT
dry snow
hail graupel
rain
1830 UT
Pujol et al., 2005
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Quasi-stationnary MCS 13-14 Oct. 1995
MESO-NH, ?x10km
OBSERVATIONS
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)
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• 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 (gt 60s)

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Fog (and low clouds)

• Microphysics
• Radiation
• Vertical resolution
• Turbulence in stable layers

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First case of Fog 7 January 2005
AROME 2 last levels cloud cover
09 TU
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First case of Fog 7 January 2005
AROME 2 last levels cloud cover
15 TU
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just a few studies with Meso-NH
But A PRIORITY for
AROME
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)
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Initialization at 03UTC
Bergot et al., 2005, submitted
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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)

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Convective boundary layersand stratocumulus

• Shallow convection
• Turbulence
• Subgrid clouds
• Microphysics
• Surface

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2005/08/20
09 TU
AROME
Meso-NH with SUBGRID COND SHALLOW 30min
Adjustment time of 30min
Meso-NH with SUBGRID COND SHALLOW Adjustment
time of 3h in the closure
Coupling with Aladin oper (r0)
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Bomex
LES
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ARM
LES
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ARM cloud mixing ratio
LES
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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)

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Stratocumulus Whats about the resolutions of
AROME ?
I.Sandu
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Liquid Water Path
I. Sandu
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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).

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Evaluation CARBOEUROPE
Forecasts of Meso-NH (8km) in an operational mode
during the experiment
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BUT limitations are well-known, inherent to
Eddy-diffusivity

• The K-diffusion doesnt 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.

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1. Countergradient with Third order moments
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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

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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