2010 Stream 3

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S 3.1 : from LOCEAN-NEMO team

S3.1-a — Title

Motivation: ....
Status : ....
main tasks : ....
(1) ...

(2) ...

Principal Investigator : name (email adress)

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S3.2 : from NOCS-NEMO team (short-term)

S3.2-a — Revisit of surface mass and salt fluxes

Motivation: As a consequence of the embedding of sea-ice into the ocean (see S3.2-b), the total mass of salt of the combined sea-ice/ocean system is conserved by removing a volume of water from the ocean when ice forms or adding a volume of water when it melts. When ice forms, salt contained in the water is returned to the ocean, less the salt retained in the ice itself. When ice melts, the salt contained is added back to the ocean.
Status : Carried over from 2009 but work is well advanced. Full testing and documentation will be complete for 3.3 release
Principal Investigator : Yevgeny Aksenov (yka@…)

S3.2-b — Embedding sea-ice inside the ocean

Motivation: To improve the coupling between the sea-ice and ocean models, we embed the sea-ice into the ocean by changing the volume of the ocean and depressing the ocean interface by a depth equal to the mean ice draft. The latter is calculated as the water equivalent of the total ice and snow mass in the model grid box using in-situ local densities of seawater. The pressure gradient that takes into account the total weight of sea ice and snow in the top model grid box is added to the ocean momentum budget. The vertical coordinate is redefined for the whole water column.
Status : During 2009 the above scheme was implemented and tested at NOCS in a 100-year long integration of an ORCA2-LIM2 configuration using both linear and non-linear free surface options. It was also tested for short runs in the ORCA2-LIM3 configurations. A longer run in ORCA2-LIM3 will take place early in 2010 and the code committed for the NEMO 3.3 release. Principal Investigator : Yevgeny Aksenov (yka@…)

S3.2-c — Embedding sea-ice inside the ocean for CICE

Motivation: Similar changes will have to be made in order to fully embed CICE-modelled sea-ice. Subtle differences and problems may arise because of the B-grid basis of CICE. This work is listed separately to ensure that possible delays will not impact on the delivery of an embedded solution for LIM in 3.3

Principal Investigator : Yevgeny Aksenov (yka@…)

S3.2-d — Lateral ocean physics

Motivation: Griffies's implementation of the Gent and McWilliams? eddy transport as a skew flux is being implemented. This has the advantage that its numerical discretization can be written in terms of contributions from quarter cells – ‘triads’. This gives a tighter stencil, disallowing 2-gridpoint numerical noise that is permitted by the advective discretization. Isopycnal diffusion is also being discretized in terms of these triads, obviating the need to smooth isopycnal slopes horizontally with a Shapiro filter (as currently implemented in NEMO), or apply a background horizontal diffusivity that would mix diapycnally. Visbeck et al.'s formulation of spatially varying diffusivities is also being implemented, as an alternative to the current formulation based on the Held and Larichev timescale and the Rossby radius as a lengthscale. Mixed-layer depth is sensitive to the slope limiting that is employed, and a slope limiting algorithm will be added that behaves satisfactorily within and immediately below the mixed layer.

Status: A working prototype code for the iso-neutral and skew-flux operator was carefully reviewed in 2009. An final version will be ready for the 3.3 release. Considerable care has been taken in the formulation to ensure the tensorial representation is consistent with the variable volume layers (S-coordinate/z* representation). This has been documented and will be provided with the release.
Principal Investigator : George Nurser (agn@…)

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S 3.3 : from MERCATOR-NEMO team

S3.3-a — Title

Motivation: ....
Status : ....
main tasks : ....
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(2) ...

Principal Investigator : name (email adress)

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S 3.4 : from Met Office-NEMO team

S3.4-a — Title

Motivation: ....
Status : ....
main tasks : ....
(1) ...

(2) ...

Principal Investigator : name (email adress)

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