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U.S. GODAE: Global Ocean Prediction with Community Effort

This project aims to develop and demonstrate eddy-resolving, real-time global and basin-scale ocean prediction systems using HYCOM. The objective is to transition these systems for operational use by the U.S. Navy at NAVOCEANO and NOAA at NCEP. The project also focuses on efficient data distribution to the community, with data availability within 24 hours through various platforms.

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U.S. GODAE: Global Ocean Prediction with Community Effort

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  1. U.S. GODAE: Global Ocean Prediction with Community Effort:NRL, U. of Miami, FSU, NASA-GISS, NOAA/NCEP, NOAA/AOML, NOAA/PMEL, PSI, FNMOC, NAVOCEANO, SHOM, LEGI, OPeNDAP, UNC, Rutgers, USF, Fugro-GEOS, Orbimage, Shell, ExxonMobil

  2. Objectives and Goals • A broad partnership of institutions that collaborate in developing and demonstrating the performance and application of eddy-resolving, real-time global and basin-scale ocean prediction systems using HYCOM. • To be transitioned for operational use by the U.S. Navy at NAVOCEANO and by NOAA at NCEP.

  3. Objectives and Goals • Strong participation of the coastal ocean modeling community in using and evaluating boundary conditions from the global and basin-scale ocean modeling prediction systems • Efficient data distribution (100 Terrabytes Storage Area Network) The data are available to the community at large within 24 hours via Live Access Server (LAS), ftp, and OPeNDAP at http://www.hycom.org

  4. Roadmap • Basin-scale • FY04 to FY08: Evaluation of data assimilation schemes [MVOI(NCODA), EnOI, SEEK and ROIF]. Improvements to the present near real time NOAA/NCEP North Atlantic configuration. Overlap in FY07 of the near real time NRL North Atlantic configuration and of the global configuration for assessment of the global system in the Atlantic. • Development of a NOAA/NCEP Pacific configuration (to become operational in FY08).

  5. http://www.hycom.org Configuration of the Basin-Scale Prediction Systems NRL NOAA/NCEP

  6. Roadmap • Global configuration • Development has been taking place since FY04. • Transition to NAVOCEANO (1/12º) with MvOI (NCODA) in FY07. • Operational testing in year FY08. • Increase to 1/25° resolution globally (~3-4 km mid-latitude) by the end of the decade

  7. Present NRL nowcast/forecast systems 1/12º Atlantic near real-time system - Running once a week since July 2002 - Assimilation: gridded surface observations only - 10 day hindcast, 14 day forecast 1/12º Global real time system - Running since December 2006 - Assimilation: NCODA - 5 day hindcast, 5 day forecast 1/25º Gulf of Mexico real time system - Running since November 2006 - Assimilation: NCODA - 5 day hindcast, 7 day forecast

  8. Present NCEP nowcast/forecast system Atlantic real-time system • Orthogonal grid (1200 x 1684 points) • 25 vertical coordinates (18 isopycnal, 7 z-level) • Forcing fields from 3-hour NCEP (GDAS/GFS) model • Tides: M2, S2, N2, K1, P1, O1, K2, Q1 tidal modes • Rivers from daily USGS data and RIVDIS climatology • Data Assimilation • SST: from GOES AVHRR and in-situ • SSH, T, S: SLA from JASON GFO; T, S from ARGO, XBT, CTD http://polar.ncep.noaa.gov/ofs/

  9. Global HYCOM configuration • Horizontal grid: 1/12° equatorial resolution • 4500 x 3298 grid points, ~6.5 km spacing on average, ~3.5 km at pole, 5 m minimum depth • Mercator 79°S to 47°N, then Arctic dipole patch • 32 σ2* vertical coordinate surfaces: • GISS or KPP mixed layer model • Thermodynamic sea-ice model • Surface forcing: wind stress, wind speed, thermal forcing, precipitation, weak relaxation to climatological SSS • Monthly river runoff (986 rivers) • Initialized from January climatology (GDEM3) T and S 216,000 CPU hrs/model year on 784 IBM Power 4+ CPUs 7.2 TB/model year for daily 3-D output

  10. FY07 Validation Tasks • Large scale circulation features • Determine correct placement of large scale features • Sea Surface Height (SSH) variability / Eddy Kinetic Energy (EKE) • Determine if the system has a realistic level and distribution of energy at depths • Mixed layer depth / sonic layer depth / deep sound channel • Compare simulated vs. observed for non-assimilated buoys • Vertical profiles of T&S • Quantitative comparison of simulated vs. observed for non-assimilated buoys • Sea surface temperature • Evaluate whether the models are producing acceptable nowcasts and forecasts of sea surface temperature • Coastal sea level • Assess the model’s ability to represent observed sea surface heights

  11. Mean Sea Surface Evaluation 1992-2002 Mean dynamic ocean topography (0.5°) Mean ocean dynamic topography data has been obtained from Nikolai Maximenko (IPRC) and Peter Niiler (SIO)

  12. Mean Sea Surface Evaluation 1/12° global HYCOM – Exp. 5.6 5 year model mean using climatological ECMWF wind and thermal forcing Std dev (HYCOM - Maximenko-Niiler) = 9.3 cm and the bias = 7.1 cm

  13. 1/12 Global HYCOM Monthly Mean Mixed Layer Depth Evaluation (Kara et al.) HYCOM MLD – MLD based on the GDEM3 climatology Annual Mean Bias in m RMS difference in m HYCOM was forced by an ECMWF ERA15 Climatology (with 6-hrly submonthly fluctuations added )

  14. SST Response in 1/12° Global HYCOM to Hurricanes Katrina and Rita NDBC buoy 42040 south of Mobile Bay NDBC buoy 42036 SE of Pensacola RMS = .67°C R = .89 RMS = .56°C R = .95 HYCOM reproduces the deterministic SST response to the wind forcing. Implies realistic upwelling and mixing of subsurface waters as well as realistic atmospheric wind and heat flux forcing.

  15. 1/12° HYCOM/NCODA/PIPS(Smedstad et al.) • Progress: 1/12° global HYCOM/NCODA running in real-time in the NAVOCEANO operational queues; validation testing has begun. • Issues: • Complete coupling of HYCOM/PIPS via ESMF (NRL) • Get NCODA working in curvilinear part of grid (NRL) • Need OcnQC running operationally (NAVOCEANO) http://www.hycom.org

  16. Data Assimilation via NCODA (Cummings et al.) Ocean obs Sequential Incremental Update CycleAnalysis-Forecast-Analysis SST: GAC/LAC MCSST, GOES, Ship, Buoy Profile: XBT, CTD, T & S profiling Floats (ARGO), Fixed Buoy, Drifting Buoy Altimeter SSHA SSM/I Sea Ice Ocean data QC Innovations Ocean data Analysis 3D MVOI & Cooper-Haines Increments Ocean model HYCOM Forecast Fields Prediction Errors First Guess MVOI - simultaneous analysis 5 ocean variables temperature, salinity, pressure, velocity (u,v)

  17. with assimilation (GLBa0.08-60.4)

  18. without assimilation (GLBa0.08-05.8)

  19. Overall increase in variability - largest changes occur in the western boundary currents

  20. 3000 cm2/s2 2500 2000 1500 1000 500 Eddy Kinetic Energy Comparison Surface EKE in the Gulf Stream Observations from Fratantoni (2001) – Based on 1990-99 surface drifters NCOM - 2004 HYCOM - 2004

  21. Eddy Kinetic Energy Comparison EKE at ~700 m in the Gulf Stream Observations from Schmitz (1996) NCOM - 2004 HYCOM - 2004

  22. Temperature Structure Comparison Locations of TAO and PIRATA buoys used in this evaluation Buoys are divided into two sets based on the vertical sampling and continuity of the time series over calendar year 2004 Set 1 (denoted by o’s): 1, 20, 40, 60, 80, 100, 120, 140, 180, 300, 500 m. Set 2 (denoted by x’s): 1, 25, 50, 75, 100, 125, 150, 200, 250, 300, 500 m.

  23. Temperature Structure Comparison 2004 subsurface temp at 140°W, 2°N Buoy / HYCOM / nonassim HYCOM Temperature difference Buoy - HYCOM / Buoy - nonassim HYCOM Significant impact of temperature profile assimilation via NCODA

  24. Set 1 Set 2 Temperature Structure Comparison HYCOM vs. non-assim HYCOM – Mean error 47 TAO/PIRATA buoys 2004

  25. Vertical Temperature Structure 2004 subsurface temp at 140°W, 2°N Temperature difference Buoy HYCOM/NCODA - Buoy V3.0 NCOM - Buoy V2.5 11th HYCOM Consortium Meeting

  26. Sea Surface Temperature Basin-wide mean error: 0°C, RMSE: .2°C Mean error – HYCOM/NCODA vs. MODAS white area = ± .25°C Over 2004 from the V3.0 hindcast simulation

  27. Sea Surface Temperature Basin-wide skill score: .90 Skill score – HYCOM/NCODA vs. MODAS Over 2004 from the V3.0 hindcast simulation

  28. Sea Surface Temperature Unassimilated MEDS SST vs. HYCOM vs. NCOM Over 2004 from the V3.0 hindcast simulation and operational V2.5

  29. 10 20 30 0 10 20 30 0 10 20 30 Forecast verification statistics from .08 global HYCOM 1.0 0.9 0.8 0.7 World Ocean NW Arabian Sea and Gulf of Oman Gulf Stream Median SSH anomaly correlation 1.0 0.9 0.8 0.7 Equatorial Pacific Kuroshio Gulf of Mexico 0.6 0 Forecast length (days) 4 Forecasts included in statistics

  30. Adding tidal capability to global HYCOM • Collaboration with tide model expert, Brian Arbic, U. Texas • For use in .04 global HYCOM with R&D starting in FY09 with state-of-the-art scientific foundation and accuracy HYCOM with 8-component tide vs tide guage HYCOM RMS errors for M2 tide vs satellite altimetry .72 resolution .08 resolution .72 HYCOM tide model tide guage Example with typical error: 89.6% of variance explained 0 5 10 15 20 25 RMS error = 6.7 cm RMS error = 9.9 cm Average RMS error over all 102 pelagic tide guages = 12.3 cm

  31. Mont St Michel Wetting and Drying in HYCOM

  32. Wetting and Drying in HYCOM Baraille et al. (SHOM) 0 meter layer thickness

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