1. 1 of 27 Moored Current Observations from Nares Strait: Andreas Münchow College of Marine and Earth Studies University of Delaware Collaborators: Drs. Melling (Canada) and Samelson (Oregon) 1.Relevance/context 2.The descriptive view 3.The statistical view 4.The “missing” view

2. 2 of 27 Dilution of the northern North Atlantic Ocean in recent decades Ruth Curry and Cecilie Mauritzen (2005, Science): How much fresh water causes salinity change? How fast does fresh water enter the sub-Arctic circulation? Where is the fresh water stored? “Excessive amounts of fresh water could alter the ocean density contrasts that drive the northernmost extension of the Atlantic MOC, diminish its northward heat transport, and substantially cool some regions …” “Great Salinity Anomaly” 0.03 Sv

3. 3 of 27 from National Sea Ice Data Center http://nsidc.org/data/seaice_index/ Sea Ice Extent March (max. extent) September (min. extent) 2006 2007

4. 4 of 27 Ice Area Extent: Deviation from 1979-2007 mean from http://www.arctic.noaa.gov/reportcard/seaice.html

5. 5 of 27 AMSR-E imagery (89 GHz): Sept.-2004 through May-2005 Agnew, Canadian Met. Service Dr. Holt of NASA/JPL

6. 6 of 27 1. Descriptive View ADCP mooring recovery, Northern Greenland, Aug.-16, 2006

7. 7 of 27 David Huntley (UDel) with “sonar Velocity: Sonars Sonars send and receives acoustic waves Measured Dopper shift proportional velocity Kennedy Channel, August 2003

8. 8 of 27 Nares Strait Freshwater Flux Experiment Velocity Snapshot (4-days) cm/s LDLD Greenland from Münchow et al. (2007) Volume Flux: Fresh Water Flux: 100-m Longitude West Latitude North 0.77±0.10  10 6 m 3 /s 28 ±4  10 6 m 3 /s

9. 9 of 27 July/August 2003 ADCP Survey Volume Flux Summary -0.77 Sv -0.92 Sv -0.91 Sv -1.03 Sv +4.3 Sv -4.8 Sv Greenland 0.9  0.10 Sv 1 Sv=10 6 m 3 /s ~5 Amazon ~1000 Delaware

10. 10 of 27 Nares Strait Hydrography, Aug.-2003 Density Temp. Salinity CanadaGreenland LDLD D L D = (∆  /  0 g D) 1/2 / f ~ 10 km   +∆  D from Münchow et al. (2006) Internal Rossby radius of deformation

11. 11 of 27 XX XXX ADCP CT/CTD All recovered instruments have clean 3-year records X X X X X X

12. 12 of 27 Nares Strait Freshwater Flux Experiment km-03, Canada km-24 km-30 Greenland, km-34 Time 20032006 30 -30 Along-Channel Currents, cm/s Velocity Time Series (3-years) cm/s Greenland ~300-km Arctic Ocean Aug. 5, 2005

13. 13 of 27 April-29, 2005 Ellesmere Island Greenland Land-fast ice cover Mooring line

14. 14 of 27 3. Statistical Views Ellesmere Island, Aug.-16, 2006: CT/CTD string recovery

15. 15 of 27 Time (days), April 2005 Sea level Atmospheric pressure Filtered sea level Adjusted sea level Alert, northern Ellesmere Island Tides and Filters

16. 16 of 27 High-resolution Power-spectra of Depth-averaged Flow at KS10 All frequencies Diurnal band Semi-diurnal band

17. 17 of 27 Kennedy Channel Tidal Ellipses of depth-averaged flow 12.42 hrs, the M 2 semi-diurnal tide 23.93 hrs, the K 1 diurnal tide

18. 18 of 27 Degrees of freedom: T/T D KS02 red (Canada) KS10 blue KS12 green KS14 black (Greenland) T D ~ 4-5 days T D ~ 1 days T D decorrelation time Trecord length

19. 19 of 27 Wind from Samelson et al (2006) KS14 (Greenland) KS10 KS02 (Canada) KS12 Note the southward flow and wind (significant at 95% confidence); Trends are in red (significant at 95% confidence)

20. 20 of 27 Record-Mean (3-year) Flow 44%35%13%8%weights KS02KS10KS12KS14mooring 0.59±0.09  10 6 m 3 /s

21. 21 of 27 April-29 2005 August-12 2005 20042005 northward flow (coastal Greenland) southward flow (channel) Mean + Seasonal Signal S a solar annual S sa solar semi-annual Flux Flow

22. 22 of 27 Principal Axes of variability after mean, trend, and seasonal variability has been removed (standard deviation)

23. 23 of 27 y, North Greenland Canada  =  (x 1,y 2,t) u=u(x,y 1,z,t)  =  (x,y 1,z,t) p=p(x,y 0,z b,t) 2 bottom pressure series 4 locations with ~30 current series 6 locations 4 density series Alert sea level and atmospheric pressure x, East  =  (x 2,y -1,z,t) Thule sea level and atmospheric pressure The “missing” view-1: Dynamics

24. 24 of 27 3-year Mean Flows Kennedy Channel Channel center, KS10 300m 0m Depth (m) 020 (cm/s)-180 90Deg. SpeedDirection The “missing” view-2: Vertical variability

25. 25 of 27 Conclusions: Array design and processing methodology sufficient to resolve scales of variability of the depth-averaged flow; Record-mean volume flux is 0.59±0.09 Sv southward; Seasonal variability has an amplitude of 0.15 Sv, thus does not reverse the mean flux; Linear trend indicates a steady increase in southward volume flux of 0.05±0.09 Sv/year which corresponds to a 25% increase from 2003 through 2006; Vertical variations and dynamics require attention desperately

26. 26 of 27 Going home … Navy Board Inlet, Aug.-2006

27. 27 of 27 Maslowski NPS

28. 28 of 27 Across-channel integral of f/g times V 0 (x) V 0 (x)=V g -V ADCP V g = relative geostrophic V ADCP = observed velocity CanadaGreenland Estimating Absolute Geostrophic Transport:

29. 29 of 27 NorthSouth