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Bogi Hansen & Hjálmar Hátún Faroe Marine Research Institute

The northern source of the Norwegian Atlantic Current. NwAC. Its forcing. and bifurcation. Østerhus et al., GRL 2005. Nordic Seas. Greenland. 3.8 Sv. 0.8 Sv. Faroe Current. 3.8 Sv. Iceland. Faroes. Scot- land. Bogi Hansen & Hjálmar Hátún Faroe Marine Research Institute.

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Bogi Hansen & Hjálmar Hátún Faroe Marine Research Institute

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  1. The northern source of the Norwegian Atlantic Current NwAC Its forcing and bifurcation Østerhus et al., GRL 2005 Nordic Seas Greenland 3.8 Sv 0.8 Sv Faroe Current 3.8 Sv Iceland Faroes Scot- land Bogi Hansen & Hjálmar Hátún Faroe Marine Research Institute

  2. The Faroe Current 4 CTD cruises a year along the standard section

  3. Deploying trawl-protected ADCP

  4. Recovering trawlprotected ADCP

  5. Definition:Atlantic water iswater that has recently crossed the Greenland-Scotland Ridge into the Nordic Seas and has not been mixed with ambient waters.

  6. 3-point mixing model

  7. Monthly and annually averaged Atlantic water transport in the Faroe Current 1997 - 2008 Average: 3.5 Sv

  8. Sea-level Wind What is the force, driving the IF-inflow ? • A stable transport requires a stable force

  9. Correlation between monthly averaged Atlantic inflow and wind stress

  10. Sea-level drop: SLHW - SLHE Transport SLHE Atlantic inflow and sea-level drop across the Ridge Iceland Faroes SLHW Scot- land Monthly correlation: R = 0.63 Annual correlation: R = 0.87

  11. Iceland Faroes Scot- land

  12. 8.5 Sv out implies lowering of Nordic Seas SLH by 30 cm/day Sea-level drop Iceland-Faroe Atlantic inflow Remote wind forcing could raise sea-level west of Ridge Outflow from Nordic Seas could lower sea-level east of Ridge R > 0 Atlantic Ocean Nordic Seas To Arctic Ocean R < 0 To Denmark Str. Atlantic inflow Iceland Faroe Ridge FBC-overflow East West IFR-overflow

  13. Correlation coefficient between monthlysea-level height and Faroe Current inflow _ +

  14. Why are the exchanges that stable ? World Ocean Nordic Seas Cooling It takes decadesto empty ”dam” Greenland Scotland Ridge Overflow AMOC

  15. Monthly averaged overflow transport through the Faroe Bank Channel (Hansen & Østerhus, 2007) Millions of m3 per second

  16. Bifurcation of Faroe Current Helland-Hansen & Nansen, 1909 Salinity at 100 m depth in May 1904

  17. PVDs from moored ADCPs(Hátún thesis, 2004)Red sticks: Surface Southern Faroe Current

  18. Two ADCP records Explains 70% of variance NB EB

  19. Seasonal transport variation from combined altimetry and geostrophy Seasonal amplitude: 0.6 Sv Maximum in March Seasonal amplitude: 0.2 Sv

  20. Windstress and bifurcation Sea-level tilt across the Southern Faroe Current Annual sea-level tilt Nordic Seas wind stress curl

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