The northern source of the Norwegian Atlantic Current
- Slides: 20
The northern source of the Norwegian Atlantic Current Nw. AC Its forcing and bifurcation Greenland Østerhus Nordicet al. , GRL Seas 2005 0. 8 Sv Faroe 3. 8 Sv Current 3. 8 Sv Iceland Faroes Scotland Bogi Hansen & Hjálmar Hátún Faroe Marine Research Institute
The Faroe Current 4 CTD cruises a year along the standard section
Deploying trawl-protected ADCP
Recovering trawlprotected ADCP
Definition: Atlantic water is water that has recently crossed the Greenland. Scotland Ridge into the Nordic Seas and has not been mixed with ambient waters.
3 -point mixing model
Monthly and annually averaged Atlantic water transport in the Faroe Current 1997 - 2008 Average: 3. 5 Sv
What is the force, driving the IF-inflow ? • A stable transport requires a stable force Sea-level Wind
Correlation between monthly averaged Atlantic inflow and wind stress
Atlantic inflow and Iceland sea-level drop across the Ridge SLHE Faroes SLHW Sea-level drop: SLHW - SLHE Transport Monthly correlation: R = 0. 63 Annual correlation: R = 0. 87
Iceland Faroes Scotland
Iceland-Faroe Atlantic inflow Remote wind forcing could raise sea-level west of Ridge Outflow from Nordic Seas sea-level 8. 5 Sv out could implieslowering of east of SLH Ridge Nordic Seas by 30 cm/day Sea-level drop Atlantic Ocean R>0 R<0 Nordic Seas To Denmark Str. Atlantic inflow West Iceland Faroe Ridge IFR-overflow To Arctic Ocean East FBC-overflow
Correlation coefficient between monthly sea-level height and Faroe Current inflow _ +
Why are the exchanges that stable ? World Ocean Nordic Seas Cooling It takes decades to empty ”dam” Overflow AMOC Greenland Scotland Ridge
Millions of m 3 per second Monthly averaged overflow transport through the Faroe Bank Channel (Hansen & Østerhus, 2007)
Bifurcation of Faroe Current Salinity at 100 m depth in May 1904 Helland-Hansen & Nansen, 1909
PVDs from moored ADCPs (Hátún thesis, 2004) Red sticks: Surface Southern Faroe Current
Two ADCP records NB EB Explains 70% of variance
Seasonal transport variation from combined altimetry and geostrophy Seasonal amplitude: 0. 6 Sv Maximum in March Seasonal amplitude: 0. 2 Sv
Windstress and bifurcation Sea-level tilt across the Southern Faroe Current Annual sea-level tilt Nordic Seas wind stress curl