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Aladin consortium activities in data assimilation

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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Aladin consortium activities in data assimilation

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  1. 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

  2. Overview • Mainframe 3D-VAR application • Background error statistics: « B » matrix • Observations and OSE • Arome prototype • Surface assimilation • Plans and collaborations EWGLAM/SRNWP meetings

  3. 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

  4. NON LINEAR AND OMEGABALANCESIN THE ALADIN Jb (G. Faure, L. Berre) EWGLAM/SRNWP meetings

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 1D+3DVar assimilation scheme for reflectivities EWGLAM/SRNWP meetings

  17. 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)

  18. 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

  19. 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

  20. Distribution of observations along the RUC (12 UTC - 0 UTC) EWGLAM/SRNWP meetings

  21. Cumul RR sur 3H : 00h-03h DyA 1 analysis RUC 1h 00-03h 50 mm/3h EWGLAM/SRNWP meetings RUC 3h

  22. DyA 1 analysis RUC 1h 03-06h EWGLAM/SRNWP meetings 138 mm RUC 3h

  23. 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

  24. 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

  25. 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

  26. Thank you for your attention

  27. 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

  28. 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

  29. 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

  30. Emissivity, AMSU-B, channel1, operational Emissivity, AMSU-B, channel1, atlas2005 EWGLAM/SRNWP meetings

  31. 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

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