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BUOYANT EDDIES ENTERING THE LABRADOR SEA OBSERVED WITH GLIDERS, FLOATS AND ALTIMETRY*

BUOYANT EDDIES ENTERING THE LABRADOR SEA OBSERVED WITH GLIDERS, FLOATS AND ALTIMETRY*. By Hjálmar Hátún (1,2), Charles C. Eriksen (1), Peter B. Rhines (1) and Jonathan M. Lilly (3) 1) University of Washington, 2) Faroese Fisheries Laboratory 3) Earth and Space Research. *Submitted to JPO.

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BUOYANT EDDIES ENTERING THE LABRADOR SEA OBSERVED WITH GLIDERS, FLOATS AND ALTIMETRY*

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  1. BUOYANT EDDIES ENTERING THE LABRADOR SEA OBSERVED WITH GLIDERS, FLOATS AND ALTIMETRY* By Hjálmar Hátún (1,2), Charles C. Eriksen (1), Peter B. Rhines (1) and Jonathan M. Lilly (3) 1) University of Washington, 2) Faroese Fisheries Laboratory 3) Earth and Space Research *Submitted to JPO

  2. Deeper component Shallower component Thermohaline circulation in the North Atlantic Ocean

  3. Heat flux Freshwater Intrusion; How ? Labrador Greenland [m] 1000 LSW 2000 3000 Freshwater intrusion into the Labrador Sea EOW

  4. W. Greenland Current Irminger Water Deep Boundary Current The main currents Greenland Labrador Sea

  5. Low High Open ocean flow pattern Greenland 700-m depth stream Function from floats (Lavender et al. 2002)

  6. Eddy activity Greenland Eddy-kinetic energy (EKE) based on satellite altimetry (Lilly et al. 2003)

  7. Seaglider 015 Seaglider 014 Winter convection Greenland Convection depth in winter 1997 (Pickart et al. 2002)

  8. North Seaglider 015 Hydrographic section from a Seaglider

  9. December 04 December 04 December 04 December 04 IW January 06 January 06 January 06 February February WGCW March EOW IW WGCW LSW Convection and freshwater intrusion observed by floats

  10. Wings 1.80 m Seabird CTD 52 kg Satellite telemetry Swim bladder The Seaglider

  11. Target A dive 3) 1) 2)

  12. (courtesy: SSALTO/DUACS) Sea surface height signature of eddies

  13. 3 2 Sea surface temperature signature of eddies 19 March Courtesy: Physical Oceanography Distributed Active Archive Center (PO.DAAC)

  14. Eddy trajectory A Seaglider trapped by an Irminger Ring

  15. Simulation Seaglider track in the eddy reference frame Observations

  16. WGCW IW Hydrographic cross-sections

  17. Density and velocity cross-sections

  18. Track of the eddy center Surface current velocities

  19. From the Seaglider Sea surface height signature Altimetry (Jason-1)

  20. Shelf-basin property exchanges Interior Labrador Sea

  21. Shelf-basin property exchanges ~200m of low- saline water

  22. Shelf-basin property exchanges ~20 cm of freshwater (S = 0)

  23. -2 -2.5 MJ/m 2.5 cm -2 43 MJ/m - 1.0 cm Contribution from one eddy to upper and lower layer Heat Freshwater

  24. Conclusions • We have given the first detailed description of a Irminger Ring immediately after its formation • The typical post-convection (April-June) freshwater influx of ~25 cm to the Labrador Sea (0-200 m layer) can be accounted for by 10 Irminger Rings • 10 Irminger Rings would also account for the observed post-convection convergence of heat in the lower (200-1000 m) layer. • 50-100% of the shelf-basin heat and salt exchange can be account for by eddies IF the eddies disintegrate in the convection region

  25. Heat flux (buoyancy flux) Dssh Adv. of buoyancy, mass or both = lateral flux Future prospects: Lateral buoyancy flux Heat flux

  26. Buoyancy convergence Density convergence Future prospects: Open ocean Greenland ? 0 W March All float profiles from 2000 to 2005 (composite 1993-2005)

  27. Future prospects:Shelves New NSF-funded project: Three Seagliders on the Iceland-Scotland ridge for three years Iceland Faroe Islands Argo float trajectories (2002 to 2005) Scotland

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