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Aladin consortium activities in data assimilation. Claude Fischer & Andras Horanyi Stolen material from: Fatima Karbou, Pierre Brousseau, Loïk Berre, Olivier Caumont, Zahra Sahlaoui, Simona Stefanescu, Alex Deckmyn. Overview. Mainframe 3D-VAR application

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slide1

Aladin consortium activities in data assimilation

Claude Fischer & Andras Horanyi

Stolen material from: Fatima Karbou, Pierre Brousseau, Loïk Berre, Olivier Caumont, Zahra Sahlaoui, Simona Stefanescu, Alex Deckmyn

EWGLAM/SRNWP meetings

overview
Overview
  • Mainframe 3D-VAR application
  • Background error statistics: « B » matrix
  • Observations and OSE
  • Arome prototype
  • Surface assimilation
  • Plans and collaborations

EWGLAM/SRNWP meetings

mainframe 3d var example of aladin france
Mainframe 3D-VAR: example of Aladin-France
  • Incremental 3D-VAR
  • Continuous assimilation cycle, 6 hour frequency, long cut-off assimilation cycle and short cut-off production, coupled with Arpège, Analysis=Model gridmesh=9.5km
  • Observations:
    • Surface pressure, SHIP winds, synop T2m and RH2m
    • Aircraft data
    • SATOB motion winds
    • Drifting buoys
    • Soundings (TEMP, PILOT)
    • Satellite radiances: AMSU-A, AMSU-B, HIRS, Meteosat-8 SEVIRI
    • QuikSCAT winds
    • Ground-based GPS zenital delays
  • Digital filter initialisation (non incremental)

EWGLAM/SRNWP meetings

non linear and omega balances in the aladin jb g faure l berre1
NON LINEAR AND OMEGABALANCESIN THE ALADIN Jb (G. Faure, L. Berre)

~ 10 cases slightly >0

10 cases ~ neutral

1 case slighlty <0

Wind 850 hPa

+12h

EWGLAM/SRNWP meetings

complex wavelets for lam a deckmyn
Complex wavelets for LAM (A. Deckmyn)
  • Wavelets are (partially) localised in both grid point space and Fourier space.
  • Diagonalization of B in wavelet space can reproduce local variations in the structure functions and standard deviations.
  • Current work is focussing on reproducing 3D structure functions for different variables (Alex Deckmyn, Tomas Landelius, Loik Berre)

Standard deviations of Temperature error

at the lowest vertical level: from data (left)

and from wavelet-B (right).

EWGLAM/SRNWP meetings

slide7

Daily small-ensemble b’s and their filtering

sb ENS 1 « FILTERED »

sb ENS 1 « RAW »

sb ENS 2 « FILTERED »

sb ENS 2 « RAW »

EWGLAM/SRNWP meetings

slide8

Towards the assimilation of microwave surface sensitive channels from AMSU-A, AMSU-B & SSM/I over land

F. KARBOU, E. GÉRARD, F. RABIER, E. BAZILE, Z. SAHLAOUI

  • Over land:
  • Only microwave channels that are the least sensitive to the surface are assimilated
  • Remaining uncertainties about land emissivity and skin temperature
  • Existing emissivity models : facilitate the assimilation of channels that receive a contribution from surface
  • The models need accurate input parameters hardly available at global scale

Need for alternatives to estimate the land emissivity

New land surface emissivity parameterisations at Météo-France

EWGLAM/SRNWP meetings

slide9

The parameterisations (Karbou et al. 2006*):

Dynamically varying emissivities derived from only one channel for each instrument

Averaged emissivities over 2 weeks prior to the assimilation period

Averaged emissivities + dynamically adjusted skin temperature from one channel for each instrument

This talk: Results from the dynamical approach (1)

* Karbou, F., E. Gérard, and F. Rabier, 2006, Microwave Land Emissivity and Skin Temperature for AMSU-A & -B Assimilation Over Land, Q. J. R. Meteorol. Soc. To appear.

EWGLAM/SRNWP meetings

slide10

Day of July 2005

Day of July 2005

Results: Observation departures from first guess: Good impact on the observation operator performances

RMS of error, AMSU-A, Glob, Period: 01 to 19 July 2005

EWGLAM/SRNWP meetings

slide11

Results: Impact on the analysis fields: Large impact on the humidity field

Low cloudiness difference field EXP-CTR (from 31 24-hour forecasts 15 Aug-14 Sept 2005)

More low clouds in EXP

  • Results are given for AMSU-A & AMSU-B assimilation over land
  • Similar results are obtained with SSM/I over land
  • Great impact on the humidity and precipitation for both AMSU and SSM/I

Less low clouds in EXP

More Stratocumulus

Less precipitating clouds

EWGLAM/SRNWP meetings

forecast scores radiosondes forecast obs ssm i over land 31 cases 15aug 14sep 2005

Results: Impact on the forecast skills: Positive impact on humidity, temperature, geopotential height

Forecast scores / radiosondes (forecast-obs), SSM/I over land, 31 cases, 15Aug-14Sep 2005

analysis

24h forecast

48h forecast

72h forecast

Temperature

Geopotential h.

EWGLAM/SRNWP meetings

3d var data assimilation in morocco
3D-VAR data assimilation in Morocco
  • Aladin cycle : cy25t1
  • Assimilation method :3d-var for upper air fields / Canari O.I. for the surface
  • Assimilation cycle : every 6 hours
  • Assimilation window :4,5h for short cutt off and 6h for long cutt off
  • Jb : standard NMC
  • Data used : conventional observations

EWGLAM/SRNWP meetings

slide14

Scores of temperature field (12h forecast) against radiosonde observations show :

    • Slightly positive impact for bias
    • Slightly negative impact on rms

Temperature 12h forecast against radiosondes (top:rms , bottom:bias)

The bias of humidity against ARPEGE analysis is reduced in low atmospheric levels (900 hPa) for all forecast ranges

Humidity at 900hPa versus ARPEGE analysis (red: dynamical adaptation & blue: 3DVAR)

EWGLAM/SRNWP meetings

slide15
Impact study of ATOVS raw radiances
  • Impact of AMSU-A is positive over areas with a lack of observations (tropical band, Sahara, ocean)
  • In mid latitudes, the impact of AMSU-A raw radiances is less marked (conflict between several observation types). More sensitivity studies are needed to optimise the use of raw radiances

EWGLAM/SRNWP meetings

P30 humidity field at 850hPa level

osse for reflectivities w meso nh aladin
OSSE for reflectivities w/ Meso-NH/Aladin

Simulated observations with « microphysical initialization »

Hu (%) + 10-dBZ contour @ 18UTC

Z (dBZ) @ 18UTC

Z (dBZ) @ 19UTC

Z (dBZ) @ 20UTC

Simulated obs. from 1D retrieval of (T,RH) + 3DVar

EWGLAM/SRNWP meetings

Simulated obs. with first guess (12 h MNH fcst)

summary outlook for reflectivities
Summary & outlook for reflectivities

Summary:

  • 1D retrieval able to correct for humidity,
  • Quality control of data and obs. op. evaluation (M. Jurašek, LACE)
  • Implementation in Arome well advanced

Future work:

  • More 1D + 3D-VAR high resolution cases
  • Perform cycling experiments,

Collaborations:

  • Introduce beam blockage in obs. op. (G. Haase, Hirlam)

EWGLAM/SRNWP meetings

arome prototype a ruc
Arome prototype: a RUC

E : first guess Px : prévision échéance x

S0 : Arome surface file at t0 A : analyse

Cx : fichier de couplage à tx

EWGLAM/SRNWP meetings

cumul rr sur 3h 00h 03h
Cumul RR sur 3H : 00h-03h

DyA

1 analysis

RUC 1h

00-03h

50 mm/3h

EWGLAM/SRNWP meetings

RUC 3h

slide22

DyA

1 analysis

RUC 1h

03-06h

EWGLAM/SRNWP meetings

138 mm

RUC 3h

surface assimilation
Surface assimilation
  • O.I. scheme (CANARI) in Arpège and Aladin (CZ and MO)
  • Probably also tested soon in Aladin-FR
  • Same algorithm to be ported into the externalized surface scheme (SURFEX) ?
  • New system for 2D analysis (maybe soil, probably PBL fields and spatialisation tool)
  • In FR: possibility to initialize fields from the coupled soil/surface/hydrology system (SAFRAN)
  • To be further discussed between Aladin and Hirlam partners at the next common workshop on surface (Toulouse, Dec. 11-13th)

EWGLAM/SRNWP meetings

plans for 2007 and outlook
Plans for 2007 and outlook
  • B matrix and background std dev.:
    • Errors of the day for screening
    • Gridpoint maps of b’s for minimization
    • Filtering of the ensemble bg errors (low-pass)
    • Native Aladin ensemble of analyses
    • Derive from those an Arome ensemble forecast
    • Wavelets (A. Deckmyn, Belgium; T. Landelius, Hirlam)
  • Algorithms:
    • FGAT (with Hungary - LACE)
    • SL TL/AD and 4D-VAR in a nutshell (F. Vaňa, LACE)
    • Incremental digital filters
    • Some kick-off on a simplified microphysics scheme for the mesoscale ?
    • Towards an integrated « Ensemble/Variational » data assimilation system; ETKF

EWGLAM/SRNWP meetings

plans for 2007 and outlook1
Plans for 2007 and outlook
  • Observations:
    • SEVIRI radiances in Hungary (LACE) and Morocco (non-LACE) ?
    • SEVIRI/CSR monitoring and bias correction; surface emissivity for IR SEVIRI channels (M. Stengel, Hirlam)
    • Metop sensors
    • Work on radial radar wind obs. operator (T. Montmerle and C. Facchani)
    • Continuation on radar reflectivity obs. op. & retrieval methods (M. Jurašek, LACE; G. Haase, Hirlam)
    • Microphysics modules for HIRS/IASI (M. Stengel, Hirlam)

EWGLAM/SRNWP meetings

slide27

AMSU-A and AMSU-B (F. Karbou):

Tb contaminated by surface conditions:

Information about surface T and 

Height of maximum sensitivity

(depends also on scan and humidity content)

  • AMSU-A and AMSU-B: temperature and humidity soundings
  • polar orbiting satellites: NOAA (15, 16, 17, 18), AQUA, MetOp
  • 20 channels: 23 to 190 GHz
  • scanning angle from -58° to +58° with V and H polarisation

EWGLAM/SRNWP meetings

slide28

New configurations tested for the surface

Several assimilation experiments

Over periods in 2005

Control run: operational model

  • Best choice so far:
  • Atlas : risk for bias
  • Dynamical comp.: risk for noise

Emissivities: - Atlas 2000

- Atlas 2005

Emissivities: dynamical computation

Emissivities: Atlas 2000 + estimation of Ts

4 different approaches are compared

EWGLAM/SRNWP meetings

slide29

New configuration for the surface

Compute surface emissivity by inverting the RT equation:

Monthly global maps at 23, 31, 50, 89 and 150 GHz for February 2000

Atlas 2000

Monthly global maps for nadir at 23, 31, 50, 89 GHz from 01 through 20 March 2005

+ parametrisation of  (Karbou 2005) to take into account the scanning angle

Atlas 2005

Emissivity computed for each meteorological situation for channel 1 AMSU-A (23GHz) and AMSU-B (89 GHz). These emissivities are attributed to the other channels without extrapolation.

Dynamical comp.

EWGLAM/SRNWP meetings

slide30

Emissivity, AMSU-B, channel1, operational

Emissivity, AMSU-B, channel1, atlas2005

EWGLAM/SRNWP meetings

slide31

Comparison of obs-guess without bias correction, 22 March through 4 April 2005

150 GHz

183+/-1 GHz

183+/-7 GHz

183+/-3 GHz

EWGLAM/SRNWP meetings