Experiences and expectations of NEMO Giving an 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 
 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 Marine ITCZ - A. Lazar

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).

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).

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)

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

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

Performance ORCA1: 15 processors : 3.59s per timestep (2.75yrs/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)

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

Drakkar code with DFS3 forcing 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)

Drake Passage and Bering Strait transport comparison ORCA025_G70 1958 - 2004

Complete and analyse N025_100 Investigate CICE vs LIM3 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

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

AGRIF nesting Bathymetry data Nesting tools T/S data

NEMO conversion to AGRIF routine AGRIF/NEMO code AGRIF/ NEMO AGRIF interface routines AGRIF library

Order-1 nest in 1° global NEMO

Order-1 nest in 1° model: surface differences (30d) Ice rheology

Schematic for calculation of fluxes at water surface Outer model Nest (modified) Example flux variables in red

Order-1 nest in 1° model: surface differences (30d) Empty boxes for ssheig and soicecov

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

No nest model vs order-3 nest in 1° model Top row: Mediterranean, bottom row: Gulf Stream 1st column 1deg model no nest; 2nd + 3rd columns 1deg model with factor 3 nest

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 IBM 2560 processors running AIX