NEMO Developments and application at the Bedford Institute of Oceanography,

CanadaF. Dupont, Y. Lu, Z. Wang, D. Wright

Nemo user meeting 2009Dalhousie-DFO

Code updates NEMO2.3

Spectral nudging enabled in NEMO. AGRIF enabled with ice included (LIM2). Neptune Effect. JGR, Holloway and Wang, accepted.Smagorinsky type eddy diffusion parametrization.OBCs fully enabled. No computed phase velocity used, advective velocity instead for radiation. Best would be to include first-baroclinic phase speed. OBC volume conservation for multi-processors: missing mask for active nodes, added double double precision summation.OBC tides, including astronomical tides.

Dalhousie-DFO Nemo user meeting 2009

Spectralnudging

No-spectralnudging

AGRIF test with ¼ degree NA with 1/12 degree embedded.

This test run has been run for only 5 years and the statistics only excludes the first 12 month

Remaining issues: correcting at each time-step E-P fields too difficult. Annual volume correction done instead.

Nemo developer meeting 2009

AGRIF NO-AGRIF

Increasing Resolution Regionally: Example of SST and Sea Ice Prediction

Based on Local Grid Refinement

Results from a 1 degree global model with a NA zoom to ¼ degree

Region with ¼ degree resolution

Results from enhanced resolution region illustrating new ability to use AGRIF in ice infested regions

White indicates ice cover

Application to the global circulation using ORCA1 (UK setup)

RMS of InterAnnual Sea-Level 1993-2004

Obs

1º model

Tropical Pacific Variability

Also reproduces changes associated with MJO

Forcing sensitivity – Interannual VariabilityForcing sensitivity – Interannual Variability

Wind

Heat

Benefit of Increased Resolution:Sub-surface Flow from ¼° model

1º NEMO Multi-Decade Simulation using CORESea-ice concentration 1990-1996

Model (left) Obs. (right)

September integrated ice area

Fram Strait transport

Regional variation in

ice area

Wind important in all regions for interannual variations

Heat forcing mostly important in REG1

March Sea-ice velocity for the last year of a 10 year run

1º model with OMIP forcing

March Sea-ice velocity for the last year of a 6 year run

1/4º model with OMIP forcing

Although ocean currents are more realistic in the 1/4° simulation, the sea ice velocities are apparently still substantially overestimated.

Code Questions

AGRIF + NEMO3: FLD issue -> has 'conv' been updated for dealing with FORTRAN structure type? If not, this sounds like a prirority.BBL issues?Restartibility issue?AGRIF + time-splitting.This would require that the barotropic variables (ssh,ua_e) are interpolated in time at each barotropic time-step and force the child domain at the boundary. Useful for tidal applications.

Dalhousie-DFO Nemo developer meeting 2009

NEMO BBL Problem

Model: NEMO2.3 ORCA1, 46 levels CORE “normal-year” forcing

Test runs: Run 1: BBL diffusion set to 2000 m2/s Run 2: BBL diffusion set to 20000 m2/s

NEMO BBL Problem

Run with small BBL diffusion

Run with large BBL diffusion