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The Greenland Sea and me

The Greenland Sea and me. Tor Eldevik Nansen Center/Bjerknes Centre, Bergen, Norway.

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The Greenland Sea and me

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  1. The Greenland Sea and me Tor Eldevik Nansen Center/Bjerknes Centre, Bergen, Norway

  2. Eldevik, T., F. Straneo, A.B. Sandø, and T. Furevik, 2005: Pathways and export of Greenland Sea Water. The Nordic Seas: An integrated perspective, H. Drange, T.M. Dokken, T. Furevik, R. Gerdes, and W. Berger, Eds., Geophysical Monograph Series, AGU, 89-103. Eldevik, T., J.E.Ø. Nilsen, K.A. Olsson, A.B. Sandø, and D. Iovino, 2006: Little trace of the Greenland Sea in the Atlantic Conveyor. In preparation. Johannessen, O.M., K. Lygre, and T. Eldevik, 2005: Convective chimneys and plumes in the northern Greenland Sea. The Nordic Seas: An integrated perspective, H. Drange, T.M. Dokken, T. Furevik, R. Gerdes, and W. Berger, Eds., Geophysical Monograph Series, AGU, 251-272. Nilsen, J.E.Ø., T. Eldevik, Ø. Skagseth, I. Fer, K.A. Mork et al., 2006: Ventilation, pathways and overflows of the Nordic Seas. In preparation. Oliver, K.I.C., T. Eldevik, D.P. Stevens and A. Watson, 2006: Simulating the life of post-convective eddies in the Greenland Sea. In revision. Olsson, K.A., E. Jeansson, L.G. Anderson, B. Hansen, T. Eldevik, R. Kristiansen, M.-J. Messias, T. Johannessen, and A.J. Watson, 2005: Intermediate water from the Greenland Sea in the Faroe Bank Channel: spreading of released sulphur hexafluoride. Deep Sea Res. I, 52, 279-294. ESOP-2 group (1999).The Thermohaline Circulation in the Greenland Sea, ESOP-2 Final Scientific Report, Bergen, Norway. TRACTOR group (2004). TRACTOR, Tracer and circulation in the Nordic Seas Region, Final science report. Report Series for the Bjerknes Centre for Climate Research 1503-8734, Bjerknes Centre for Climate Research, Bergen, Norway. ProClim papers:

  3. From the folklore “Until recently we would find giant ‘chimneys’ in the sea where columns of cold, dense water were sinking from the surface to the seabed 3,000 metres below, but now they have almost disappeared,” Wadhams said. “As the water sank it was replaced by warm water flowing in from the south, which kept the circulation going. If that mechanism is slowing, it will mean less heat reaching Europe.” Sunday Times 8/5/05 Tor Sponga, BT

  4. Is the Greenland Sea a major part of the Atlantic Conveyor? From Nansen (1906) to Hansen et al (2001) Mauritzen (1996) Hansen and Østerhus 2000 The rate of water mass transformation must match the strength of the circulation

  5. uE~0.3×Ugeo=2×10-3m/s F~0.5Sv (FGSDW~0.2SV) Q~2TW (QNwAC~200TW), q=50W/m2 0.5Sv ↔ sinking ~100m/yr ←?→ NWAC The capacity of the Greenland Sea r~100km, L~50km, H~500m, ΔT=1ºC Q

  6. The recent GSW contribution to the Atlantic Conveyor DS: ~0.1 Sv GSW × 0.6Sv(Girton et al 2001) FBC: ~0.3 Sv GSW × 1.7Sv (Hansen and Østerhus 2000) 0.4/6 = 7% SF6: 10% + 45% Consistent with OGCM Eldevik et al. (2005) Olsson et al. (2005) Hansen and Østerhus 2000

  7. So what? There’s been no real convection in the Greenland Sea since the 70s… Let’s look at the available data back to 1950

  8. The GSW contribution to AMOC from hydrographic data (NISE) Content DS FSC

  9. The GSW contribution to AMOC from hydrographic data (NISE) Fluxes DS FSC

  10. The GSW contribution to AMOC from model data (NERSC) DS 1Sv GSea No correlation FSC 1Sv

  11. The GSW contribution to AMOC from model data (NERSC) DS 1Sv GSea No correlation (Bentsen et al., 2004) FSC 1Sv

  12. The GSTRE and what I have learned from it • The GSTRE traces out the pathways of the Nordic Seas, and the exchanges with the Atlantic and Arctic oceans. • It is a real and suitable benchmark for ocean models. • The variability in tracer pathways and export reflects changes in the patterns and strength of the internal circulation of the Nordic Seas, and not in the fluxes of the overflows. • There is no clear link between the ventilation of the Greenland Sea and the "Atlantic Conveyor".

  13. Simulating the life of post-convective vortices in the Greenland Sea (in revision, 2006) Kevin Oliver School of Environmental Sciences University of East Anglia Norwich, U.K. Tor Eldevik G. C. Rieber Climate InstituteNansen Environmental and Remote Sensing Centre Bergen, Norway David Stevens School of Mathematics University of East Anglia Andrew Watson School of Environmental Sciences University of East Anglia

  14. SCVs in the Greenland Sea An SCV at 75N 0E, near the Greenland Fracture Zone (GFZ) Gascard et al, 2002. See also Wadhams et al, 2002, 2004, Budeus et al, 2004, Kasajima et al, 2006

  15. Mean density and circulation in the model at 850m Boreas Basin GFZ Greenland Basin Boundary between two sub-gyres No EGC but gyre around both basins Mean anticyclone in centre of Greenland Basin 400 km

  16. Tracer and velocity at 850m depth Zoom in on green box

  17. Tracer and velocity at 850m depth Zoom in on green box

  18. Tracer Temperature Velocity section Formation and migration of an SCV Ambient vertical shear Quasi-dipole formation Migration down the isopycnal slope

  19. Summary- Greenland Sea and AMOC • The ”capacity” of the GSea/contribution to the conveyor is <10% • Pre- or post 1970s (deep convection) does not matter • Nordic Seas: the rate of water mass transformation must match • the strength of the circulation • What is the link between convection and circulation?

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