1. Line W: A sustained measurement program sampling the North Atlantic Deep Western Boundary Current and Gulf Stream about 39°N 70°W Image copyrighted by Ocean Remote Sensing Group, JHU/APL J. Toole, R. Curry, T. Joyce, B. Peña-Molino, W. Smethie and J. Smith

2. Line W Contribution to AMOC Study in collaboration with the U.K. Rapid Programme Research supported by U.S. National Science Foundation MOVE RAPID Line W focus: Cold limb of the MOC between Cape Hatteras and Grand Banks

3. Sustained measurement program consists of a moored array and repeated hydrographic sampling Adjacent to SYNOP, Rise and SEEP arrays; Downstream from Halkin & Rossby

4. Field Program Shipboard sampling 2004-2008: spring and fall cruises CTD/O 2, LADCP, SADCP, CFCs, 129 I --------------------------------- 2008-2013: one cruise/year Moored Array 2004-2008: 2 conventional (2-yr endurance) 3 MMP (annual service) 1 conventional (2.5 yr) -------------------------------- 2008-2013: 4 conventional 2 MMP All on 2-year service schedule

5. Average LADCP Velocity Section 2004-2006 mean velocity profiles along-isobath component ULSW+CLSW+ ISOW+DSOW 25 ± 4 Sv

6. Equatorward transport across Line W partitioned by water mass: ULSW (yellow), CLSW (green), ISOW (purple), DSOW (black)  GS Rings near array red squares = ship data

7. ~60% of the sub-inertial variance accounted for by depth-independent motions Along-isobath variance is ~twice the across-isobath Due chiefly to motions at periods longer than a month

8. ~60% of baroclinic variance accounted for by 1 st EOF mode Red = along-isobath component Black = across-isobath Similar to first baroclinic mode for flat-bottom ocean, but bottom isn’t flat

9. Dynamical baroclinic modes flat bottom sloping bottom TRW N 2 profile

10. Kinetic Energy Frequency Spectra from W2 Black = 1000 m Red = 2700 m (more) evidence of Topographic Rossby Wave variability

11. Water Property Distributions

12. Receives the products of convection, overflow and entrainment that pass through Labrador Sea and ventilate the Atlantic deep basins

13. Time series of 129 I concentrations in Denmark Strait and Labrador Sea and at Line W from John Smith (BIO).

14. Line W is ongoing Just recovered the array for 2006-2008 deployment Once we process the recovered data, we will work to produce transport time series for the period 2004-2008 Invite collaborations to use these data help us learn how the time-varying DWBC at 39°N 70°W fits into the North Atlantic MOC