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Experiences and expectations of NEMO

Experiences and expectations of NEMO. Andrew C. Coward, Steve Alderson and Beverly de Cuevas. Benefits of NEMO: Curvilinear grids - tripolar. NEMO Users meeting : Thursday 22nd (afternoon) and Wednesday 23rd (morning) May 2007 ･ Coupled models CICLE project at the CNRM - M. Lucas

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Experiences and expectations of NEMO

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  1. Experiences and expectations of NEMO Andrew C. Coward, Steve Alderson and Beverly de Cuevas

  2. Benefits of NEMO: Curvilinear grids - tripolar

  3. NEMO Users meeting : Thursday 22nd (afternoon) and Wednesday 23rd (morning) May 2007･ • Coupled models • CICLE project at the CNRM - M. Lucas • MERSEA project and ECMWF system 4 prototype - A. Troccoli • First analyses of the new version of the sintex-F coupled model - C. De Boyer Montegut • Progress on incorporating NEMO into the next Met Office climate model - C. Harris • Grid computing with ARPEGE-NEMO coupled model - E. Maisonnave • Operational Oceanography • UK operational ocean forecasting with NEMO - A. Sellar • 1/12｡ ocean simulations with Mercator configurations - Y. Drillet • The MERSEA/Mercator Ocean global 1/4｡ analysis and forecasting system V2 : first results - G. Garric • Implementing NEMO in the new version of the Mediterranean Forecasting Sytem - S. dobricic for P. Oddo • Biogeochemistry of the ocean • Iron and C13 in NEMO-PISCES - A. Tagliabue • Biowaves project: first results from coupled physical/biogeochemical simulations in the N. Atlantic - G. Charria • Modeling the neodymium isotopic composition with the NEMO global ocean circulation model - T. Arsouze • Evidence for strong submesoscale variability of pCO2 in the northeast Atlantic Ocean - L. Resplandy • Developments / Portability • LIM3 a new sea ice model coupled to OPA - M. Vancoppenolle • Toward an alternative to the Leap Frog time stepping - M. Leclair • Impact of optimized calculation of Coriolis terms in the Mediterranean model set-up - S. dobricic • An update on the OASIS coupler development - S. Valcke • Dynamics of the ocean • Decadal variability of oxygen, temperature and salinity in mode and intermediate waters - J. Clark • SSS sensitivity in the Eastern North Atlantic subtropical gyre - B. Mourre • Diagnosis of IGW in an OGCM : an intercomparison between numerical simulations and in situ-measurements - X. Levaillant (pdf)
 • Diagnosing the ocean control on the seasonal migration of the MarineITCZ - A. Lazar

  4. OCEANS 2025: Themes and selected scientific objectives Theme 9: Next Generation Ocean Prediction Systems: • How sensitive are climate models to the manner in which sea ice is coupled? • Can nested models be trusted to give accurate results? • Can an ocean model be made energetically self-consistent? • What is the most appropriate level of complexity of biogeochemical models in climate studies? Approaches and methodologies: • Develop NEMO as the core OGCM for use by the scientific community in the UK, at resolutions of 1°, ¼°and 1/12°, and with nested grids (WP 9.10). • Develop an ocean model testbed permitting objective intercomparison and validation of a range of ecosystem models, with a view to embedding the most promising in OGCMs (WP 9.11).

  5. OCEANS 2025: Themes and selected scientific objectives Theme 2: Marine Biogeochemical Cycles • To determine the sensitivity to future climate change of the mechanisms sustaining total nutrient supply to the photic zone over the three major biomes of the North Atlantic. Approaches and methodologies: • Quantify the magnitude and sensitivity of nutrient fluxes associated with winter overturning and Ekman pumping. For overturning, this will be achieved using time-series stations, Argo floats and mooring data together with previous studies and basin-scale simulations (NEMO both at ¼º and with a smaller scale nested component at 1/12º in the North Atlantic).

  6. OCEANS 2025: Themes and selected scientific objectives Theme 1: Climate, Ocean Circulation, and Sea Level • Model simulations of climate change in the ocean • Identifying the causes of recent climate change in the ocean • Physical-biogeochemical budgets and mixing in the Southern Ocean (DIMES) Research plan and deliverables: • 2008: Completed simulation of changes in the ocean over the period 1950 - 2006 obtained by running NEMO globally at 1/4° resolution (and with a nested 1/12° North Atlantic grid) using NCEP/NCAR (and possibly ECMWF) derived surface flux fields (WP 1.1b)

  7. The UK is moving towards a more coordinated approach based on the NEMO model • This forms the core of “OCEANS 2025” with plans for (amongst others): • Global 1/4o models with biogeochemistry and 1/12o nested regions • Global 1/12o physics only model by 2010

  8. Theme 9: NOCS NEMO activities • Produced global 1 degree NEMO configuration (ORCA1) [shared with UKMO] • Tested ORCA1 with “LOBSTER” NPZD model, about to test new NOCS biogeochemistry model “MEDUSA” • Developed “interpolation on the fly” option for handling surface forcing fields • Constructed ORCA1 forcing datasets which are compatible with those used with the current DRAKKAR (global 1/4o) model • Completed multi-decadal integrations of ORCA025 • Developed capability to run AGRIF nests in sea-ice regions

  9. Performance ORCA1: 15 processors : 3.59s per timestep (2.75yrs/day) ORCA1: 30 processors : 1.97s per timestep (5yrs/day) ORCA1: 32 processors with LOBSTER : 3.57s per timestep ORCA025: 56 processors: Avg ts = 14.2634 ( 9 entries ) Min = 12.016 Max = 28.412 (0.28yrs/day) On HECToR: ORCA025: 221 processors: Avg ts = 2.44 ( 14400 entries ) Min = 2.13 Max = 7.533 (1.6yrs/day) 16 processors 1.5s per timestep (~ 7 years/day) 64 processors 4.5s per timestep (~ 0.6 years/day) 512 processors 7.2s per timestep (~0.12 years/day)

  10. Current status of Drakkar configurations • at NOCS • Steven Alderson, Andrew Coward, Beverly de Cuevas, Adrian New, George Nurser, Yevgeny Aksenov, Jeff Blundell, Jeremy Grist

  11. N025_100 run (NOCS) • Drakkar code with DFS3 forcing • On-line interpolation of atmospheric fields • cdmp = 0.0333 (5 times weaker than G70) • icedmp = 25 (same as G70) • 1958 - 2004 (currently1997)

  12. Drake Passage and Bering Strait transport comparison N025_100 1958 - 1975 ORCA025_G70 1958 - 2004

  13. NOCS plans for 2008 • Complete and analyse N025_100 • Investigate CICE vs LIM3 • Extend tests with AGRIF in North-west Atlantic • Run ORCA025 with biogeochemistry

  14. Experiments with AGRIF at NOCS Oceans 2025 Steven Alderson Work Package 2.5: “… NEMO will be run globally at 1/4° with biogeochemistry and with a higher resolution 1/12° nested model ….”

  15. AGRIF nesting Bathymetry data Nesting tools T/S data

  16. NEMO conversion to AGRIF NEMO Conversion routine AGRIF/NEMO code AGRIF/ NEMO AGRIF interface routines AGRIF library

  17. Order-1 nest in 1° global NEMO

  18. Order-1 nest in 1° model: surface differences (30d)

  19. Schematic for calculation of fluxes at water surface Outer model Nest (modified)

  20. Order-1 nest in 1° model: surface differences (30d)

  21. 1° model vs order-3 nest in 1° model: SST (4mnth) latitude longitude longitude

  22. No nest model vs order-3 nest in 1° model

  23. Further work • Continuity across restart files • Higher resolution run (standard mpi_send) • Blanking of areas (e.g. Pacific) • AGRIF with biogeochemical models • Southern Ocean region

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