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Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Aladin consortium activities in data assimilation Claude Fischer & Andras Horanyi Stolen material from: Fatima.

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Presentation on theme: "Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Aladin consortium activities in data assimilation Claude Fischer & Andras Horanyi Stolen material from: Fatima."— Presentation transcript:

1 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings 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

2 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Overview 1. Mainframe 3D-VAR application 2. Background error statistics: « B » matrix 3. Observations and OSE 4. Arome prototype 5. Surface assimilation 6. Plans and collaborations

3 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings 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)

4 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings NON LINEAR AND OMEGA BALANCES IN THE ALADIN Jb (G. Faure, L. Berre)

5 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Wind 850 hPa +12h ~ 10 cases slightly >0 10 cases ~ neutral 1 case slighlty <0 NON LINEAR AND OMEGA BALANCES IN THE ALADIN Jb (G. Faure, L. Berre)

6 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings 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).

7 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Daily small-ensemble  b’s and their filtering  b ENS 2 « RAW »  b ENS 2 « FILTERED »  b ENS 1 « FILTERED »  b ENS 1 « RAW »

8 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings 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

9 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings The parameterisations (Karbou et al. 2006*): 1)Dynamically varying emissivities derived from only one channel for each instrument 2) Averaged emissivities over 2 weeks prior to the assimilation period 3) 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.

10 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings RMS of error, AMSU-A, Glob, Period: 01 to 19 July 2005 Day of July 2005 Results: Observation departures from first guess: Good impact on the observation operator performances

11 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings More low clouds in EXP More Stratocumulus Less precipitating clouds Less low clouds in EXP Low cloudiness difference field EXP-CTR (from hour forecasts 15 Aug-14 Sept 2005) Results: Impact on the analysis fields: Large impact on the humidity field 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

12 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings 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 analysis24h forecast48h forecast72h forecast Temperature Geopotential h.

13 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings 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

14 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Temperature 12h forecast against radiosondes (top:rms, bottom:bias) Scores of temperature field (12h forecast) against radiosonde observations show : Slightly positive impact for bias Slightly negative impact on rms Humidity at 900hPa versus ARPEGE analysis (red: dynamical adaptation & blue: 3DVAR) The bias of humidity against ARPEGE analysis is reduced in low atmospheric levels (900 hPa) for all forecast ranges

15 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Impact study of ATOVS raw radiances ã Impact of AMSU-A is positive over areas with a lack of observations (tropical band, Sahara, ocean) ã 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 P30 humidity field at 850hPa level

16 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings 1D+3DVar assimilation scheme for reflectivities

17 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings OSSE for reflectivities w/ Meso-NH/Aladin Simulated obs. with first guess (12 h MNH fcst) Z 20UTCZ 18UTCZ 19UTCHu (%) + 10-dBZ 18UTC Simulated observations with « microphysical initialization » Simulated obs. from 1D retrieval of (T,RH) + 3DVar

18 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings 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)

19 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Arome prototype: a RUC E : first guessPx : prévision échéance x S0 : Arome surface file at t0A : analyse Cx : fichier de couplage à tx

20 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Distribution of observations along the RUC (12 UTC - 0 UTC)

21 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Cumul RR sur 3H : 00h-03h DyARUC 1h RUC 3h 00-03h 50 mm/3h 1 analysis

22 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings DyARUC 1h RUC 3h138 mm 03-06h 1 analysis

23 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings 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 th)

24 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings 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

25 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings 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)

26 Thank you for your attention

27 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings AMSU-A and AMSU-B (F. Karbou): 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 Tb contaminated by surface conditions: Information about surface T and  Height of maximum sensitivity (depends also on scan and humidity content)

28 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings 4 different approaches are compared Several assimilation experiments Over periods in 2005 Control run: operational model Emissivities: - Atlas Atlas 2005 Emissivities: dynamical computation Emissivities: Atlas estimation of Ts Best choice so far: -Atlas : risk for bias -Dynamical comp.: risk for noise New configurations tested for the surface

29 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Compute surface emissivity by inverting the RT equation: Atlas 2000 Monthly global maps at 23, 31, 50, 89 and 150 GHz for February 2000 Atlas 2005 Monthly global maps for nadir at 23, 31, 50, 89 GHz from 01 through 20 March parametrisation of  (Karbou 2005) to take into account the scanning angle Dynamical comp. 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. New configuration for the surface

30 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Emissivity, AMSU-B, channel1, operational Emissivity, AMSU-B, channel1, atlas2005

31 Zürich 9th-12th, 2006EWGLAM/SRNWP meetings Comparison of obs-guess without bias correction, 22 March through 4 April GHz 183+/-1 GHz 183+/-3 GHz 183+/-7 GHz


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