AMEN (NATL4 + AGRIF) A tlantic M ode water E xperiment using N emo/Agrif

1. AMEN (NATL4 + AGRIF)Atlantic Modewater Experimentusing Nemo/Agrif Virginie Thierry, Sébastien Theetten, Jean-Marc Molines, Anne-Marie Tréguier, Carole Grit Drakkar Team, Nemo team, Agrif Team Drakkar Meeting - Grenoble

2. Scientific Objectives Study mode water in the North-East Atlantic: formation, properties, subduction and variability • Identify formation area • Understand mechanisms that setup its properties • Determine the link between NAO index or other atmospheric indexes and mode water properties • Investigate the way mode water ventilates the ocean interior • Evaluate the ability of Drakkar model configurations to simulate correctly water masses and mode water in the eastern part of the North-Atlantic Drakkar Meeting - Grenoble

3. AMEN model configuration AMEN : refinement in NATL4 in the North-East Atlantic • NATL4: Atlantic ocean, 20°S-80°N • Agrif zoom : 30°W-0°E, 31°N-55°N Drakkar Meeting - Grenoble

4. AMEN model configuration • NATL4: ¼° resolution, eddy permitting, sea ice, closed boundaries, 486x529x64 grid points, time step: 2400S, • Agrif zoom: 1/12°, eddy resolving, 383x397x64 grid points , time step: 720S, • 64 grid points on the vertical: • 36 levels within the first 1000 m, 6m at the surface, 50m at 500 m, 200 m at 5900 m • Agreement with the NOC • Bathymetry in Agrif zoom • Identical to Mercator NATL12 bathymetry (for validation, exchanges purposes) Drakkar Meeting - Grenoble

5. AGRIF validation ►SALINITY Drakkar Meeting - Grenoble

6. AGRIF validation Annual mean of EKE averaged along the western boundary Low-resolution grid High-resolution grid Drakkar Meeting - Grenoble

7. AGRIF validation Annual mean of EKE averaged along the southern and northern boundary Low-resolution grid High-resolution grid Drakkar Meeting - Grenoble

8. Mode water in ORCA025-G70 Example of profile containing mode water 18°W – 44°N July 2001 Identify by PV < 6 10-11 m-1 s-1 Drakkar Meeting - Grenoble

9. Mode water in ORCA025-G70 Density of the mode water core 2001 1991 Drakkar Meeting - Grenoble

10. Mode water in ORCA025-G70 Potential temperature of the mode water core 2001 1991 Drakkar Meeting - Grenoble

11. Mode water in ORCA025-G70 T/S diagram in the POMME area ORCA 1993 / ORCA 2000 / POMME ORCA 1993 / ORCA 2000 / POMME In the POMME area, central water are fresher in ORCA025 than in the data Drakkar Meeting - Grenoble

12. Mode water in ORCA025-G70 Time series of the mode water properties at 18°W-44°N Over the period 1991-2001, the mode water is getting warmer, saltier, lighter Consistent with the observed warming of the cental water in the Bay of Biscay over 1992-2003 (Gonzalez-Pola et al 2005) Drakkar Meeting - Grenoble

13. Workplan 2007 • Finalize the configuration and run the simulation • Resolve med water problem ! • Validate the simulation with the large data set available in the area: POMME, OVIDE, ARGO and historical data • Investigate mode water properties variability in using the model and the data and mechanisms of this variability • Comparison with ORCA025-G70 2008 • Use the Lagrangian tool Ariane to determine formation area, ventilation area and ventilation processes • Comparison with NATL12 • … Drakkar Meeting - Grenoble

14. Questions • What forcing field shall we use ? • The target period is 1980-2006 • Large data set in the 80’s (see J. Paillet thesis) • Woce data in the 90’s • POMME: 2000-2001 • OVIDE: 2002, 2004, 2006 Drakkar Meeting - Grenoble

15. Thank you Drakkar Meeting - Grenoble

16. Mode water in ORCA025-G70 Salinity of the mode water core 2001 1991 Drakkar Meeting - Grenoble

17. Mode water in ORCA025-G70 Potential vorticity of the mode water core 2001 1991 Drakkar Meeting - Grenoble

18. Mode water in ORCA025-G70 Thickness of the mode water layer 2001 1991 Drakkar Meeting - Grenoble