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TOPAZ evaluation

TOPAZ evaluation. L. Bertino, F. Counillon, P. Sakov Mohn-Sverdrup Center/NERSC. GODAE workshop, Toulouse, June 2009. TOPAZ System overview. System description Validation of TOPAZ Data Assimilation. Satellite Data SLA, SST, Ice, In Situ Data. Atmospheric Data. Sea-Ice model.

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TOPAZ evaluation

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  1. TOPAZ evaluation L. Bertino, F. Counillon, P. Sakov Mohn-Sverdrup Center/NERSC GODAE workshop, Toulouse, June 2009

  2. TOPAZ System overview System description Validation of TOPAZ Data Assimilation

  3. Satellite Data SLA, SST, Ice, In Situ Data Atmospheric Data Sea-Ice model Atlantic and Arctic model EnKF Data assimilation system Gulf of Mexico model Eco- system model Uncertainty estimates Ocean Primary production Hindcast studies User-targeted ocean forecasting Analyze the ocean circulation, sea-ice and biogeochemistry. Provide real-time forecasts to the general public and industrial users

  4. The TOPAZ model system • TOPAZ3: Atlantic and Arctic • HYCOM + EVP sea-ice model • 11- 16 km horizontal resolution • 22 hybrid layers • EnKF • 100 members • Observations • Sea Level Anomalies (CLS) • Sea Surface Temperatures (NOAA) • Sea Ice Concentr. (AMSR, NSIDC) • Sea ice drift (CERSAT) • Argo T/S profiles (Coriolis) • Runs weekly, 10 days forecasts • ECMWF forcing • http://topaz.nersc.no/thredds • http://thredds.met.no (MERSEA…)

  5. EnKF Correlations 3rd Jan 2006 8th Nov 2006

  6. The HYCOM model • 3D numerical ocean model • Hybrid Coordinate Ocean model, HYCOM (U. Miami) • US Navy global forecasts • Hybrid coordinate • Isopycnal in the interior • Z-coordinate at the surface • Terrain following (sigma) • Nesting capability • Coupled • Sea-ice model • Ecosystem models • Large community (http://www.hycom.org)

  7. Nesting • Bring dynamically consistent information from large-scale circulation to coastal seas • One-way nesting • “Flather” condition for barotropic mode • Avoids reflection of waves at the boundary • Simple relaxation for the baroclinic mode • And for the tracers • Arbitrary resolution and orientation of the nested grids

  8. Effect of the upgradeWeekly SSS in Dec. 1999, free run MICOM BCM TOPAZ3 TOPAZ4

  9. TOPAZ System overview System description Validation Data Assimilation

  10. 3 Validation criteriacf weather forecasting (Murphy, 93) • Consistency • Are the operational forecasts in agreement with known processes of the ocean circulation? • Accuracy • How close to reality are the results? • Performance (value) • Advantage over any trivial forecast? • climatology, persistence

  11. Validation Metrics • Problems: • Validating and comparing GODAE systems consistently • Different model horizontal grids / Vertical coordinates • Large amounts of 4D data • Large data transfers • Solutions adopted (during Mersea Strand 1, 2003-2004) • 4 Classes of output products (3D, 2D, time series, residuals) • Common output grids (1/8th deg, projection...) • Self-documented file format (NetCDF) • Inter-operable file access (OPeNDAP/THREDDS)

  12. Arctic Metrics

  13. Validation against hydrographic data June07 Sept07 Topaz2 Topaz3 IMR

  14. Online comparison to Argo profiles

  15. Sparse profiles under iceNPEO deployment 2006 --- TOPAZ — NPEO *: North Pole Environment Observatory

  16. Water fluxes

  17. Sea-ice edgeVisual comparison • Ice concentration from model in color, SSMI 15% ice contour in black. Ice drift is overlaid. • Good overall correspondence between model and data • Visual comparison allows identification of problematic regions • West of Novaya Zemlya - a tendency for the ice edge to drift too little to the north during a forecast cycle • South of Svalbard (Bear Island) model ice edge too far to the north • Issues related to model physics • Ice-ocean momentum exchange • Ice models neglect physics which may be important on small scales • Fast ice • MIZ

  18. Forecast skills by region Barents Sea Alaska Bering Strait Central Arctic Greenland Sea Kara Sea

  19. SLA assimilation residualsAzores box

  20. MERSEA sections updated • Blue: MERSEA Class2 sections • Red: Sections from IMR

  21. TOPAZ System overview System description Validation Data Assimilation

  22. Assimilation of Ocean Color in HYCOM-NORWECOM • Data: • Satellite Ocean Color (SeaWIFS) • Coupled Model: • HYCOM-NORWECOM • (7 compartments) • Problems: • Coupled 3-dimensional • physical-biological model. • High-dimension. • Non-Gaussian variables. • Perspectives: • Environment monitoring. • Fisheries. • Methodological developments • for future coastal HR systems.

  23. Gaussian anamorphosis with the EnKF Anamorphosis: prior transformation of the variables in a Gaussian space (Bertino et al. 2003) Twin experiments (surface chlorophyll-a synthetic observations) Surface CHLa RMS error EnKF Cut-off of neg. values Gaussian Anamorphosis EnKF Simon & Bertino (OSD, 2009)

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