Improvement of model configurations ORCA025, NATL12, NATL4-AGRIF

1. DRAKKAR PLANED ACTIVITIES 2007-2010 LEGI/LPO/LOCEAN Improvement of model configurations ORCA025, NATL12, NATL4-AGRIF Variability of the subpolar Atlantic (ORCA025, NATL12, NATL4) Variability of the Southern Ocean (ORCA025, PERIANT025, AGRIF)

2. Improvement of model configurations ORCA025, NATL12, NATL4-AGRIF • 1 - Internal parameterisations : • Sensitivity to the vertical resolution (64 levels?) • Parameterisation of subgridscale at ¼° resolution • Parameterisation of the vertical mixing (tidal mixing in the Indonesian throughflow) • Values of several key sea-ice parameters • 2 - Improvement of atmospheric forcing : • space/time resolution of satellite winds, • freshwater forcing, • diurnal cycle in solar heat flux, • accuracy of the atmospheric surface variables on recent periods (1990’s and 2000’s).

3. 3 - Eddy-resolving resolution : • Further developNATL12 configuration & local AGRIF refinement in NATL4(AMEN) • Validate in application studies on the role of the ocean mesoscale turbulence on water mass formation and cross-front transports.   • 4 - Development of validation tools • Development of statistical tools for a systematic quantitative model-observation comparisons with global observational databases(ENACT/ENSEMBLES & AVISO).

4. Variability of the subpolar Atlantic • (ORCA025, NATL12, NATL4) • 1 - Mode water variability (AMEN)(Virginie Thierry, A.M. Treguier, collaboration with Eric de Boisséson and the OVIDE team) • Identify the formation areas of subpolar mode water in the Eastern North Atlantic • understand the mechanisms that set up its properties and its variability • investigate the way mode water ventilates the interior of the gyres • 2 - Characterisation of the boundary currents variability from high frequency to the decadal scale, and forcing mechanisms(A.M. Treguier, C. Guiavarc’h (post doc in 2007), a PhD student to start in 2007 at LPO, Gaelle Hervieux, PhD student at LEGI (2007), B. Barnier, T. Penduff, A. Wirth) • Connexion between the Greenland-Iceland-Scotland overflow and the deep boundary current (2007) • Interannual to decadal variability of the DWBC from the overflows to the subtropical gyre (2007-2008) • High frequency variability of the boundary currents in the North Atlantic (2007) • Wind-forced variability of the boundary current in the Irminger Sea (2007-2010) • Variability modes and local processes (2007-2009) • Exchanges between the boundary current and the interior (2008-2010)

5. 3 - Variability modes and local processes (2007-2009)Participants: T. Penduff (LEGI), A. Lecointre (PhD starting in 2006, LEGI), A.M. Treguier (LPO), PhD student to start in 2008/2009 (LPO), B. Barnier (LEGI). • to characterize and study the transports of properties (especially mass, heat, salt) and their low-frequency fluctuations across the selected sections(48°N, 36°N, 24.5°N, 52°W, 66°W, WOCE A1E/AR7E Greeland-Ireland transect, OVIDE). • to relate these 2D structure with basin-scale modes of variability, using observed, reanalyzed, and simulated data. • 4 - Exchanges between the boundary current and the interior (2008-2010) • Participants: A.M. Treguier, T. Penduff, B. Barnier, J. Le Sommer, G. Madec, PhD student at LPO. Collaboration with the OVIDE team and Bruno Blanke. • mass exchanges between the boundary current, the overflows, and the interior of the gyres; • water mass formation and transformation, by atmospheric forcing and mixing processes on the basin scale (including the boundary current).

6. Variability of the Southern Ocean • (ORCA025, PERIANT025, AGRIF) • 1 - Dynamics and variability of the Antarctic Circumpolar Current • - Role of eddies in the density balance of the ACC • Participants: A.M. Treguier at LPO. Cooperation with S. Rintoul from CSIRO and M. England from UNSW in Australia. • - Role of eddies in the momentum balance of the ACC • Participants: J. Le Sommer at LEGI, A.M. Treguier at LPO and B. Barnier at LEGI. Ongoing discussion with C. Wilson at University of Liverpool. • Is the geographical distribution of eddy vorticity forcing in the model simulations consistent with direct observations? • What is the vertical structure of the eddy vorticity forcing? • How is the eddy vorticity forcing related to topographic steering?

7. 2 - Life-cycle of Antarctic Bottom Water • - Role of katabatic winds and polynia on the production of AABW (MAR). Participants: Pierre Mathiot (PhD student at LEGI), with contributions from B. Barnier, J. Le Sommer and J. M. Molines at LEGI, H. Gallée LGGE, A. M. Treguier at LPO. Cooperation with S. Rintoul and M. England from CSIRO in Australia. Ongoing discussion with A. de Montety et H. Goose for a possible cooperation with UC Louvain la Neuve. • What is the impact of the katabatic winds on the local ocean circulation and sea-ice cover? • What is the contribution of Antarctica’s Coastal polynyas to the formation of Antarctic Bottom Water (AABW), a major component of the world ocean meridional circulation? • 3 - Life-cycle of Mode Waters (SAMW and AAIW) • - Semi-annual variability of Intermediate waters.Participants : J. Le Sommer (LEGI), collaboration M. England (UNSW) • Does the SAO force the variability of water mass properties observed by Sun and Watts, 2002? • Does the modulation of properties correspond to a variability of formation rates? • Is the oceanic response dependent on the mechanical forcing (Ekman/subduction) or rather the thermodynamic forcing (heat and freshwater fluxes)?

8. 4 - Variability of cross frontal exchanges.Participants: A.M. Treguier, J. Le Sommer and G. Madec, collaborations with M. England, S. Rintoul, S. Speich and M. Arhan. One post-doc or PhD student sought for 2008. GOODHOPE project.