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 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 of 27 from National Sea Ice Data Center Sea Ice Extent March (max. extent) September (min. extent)

4 of 27 Ice Area Extent: Deviation from mean from

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

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

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 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 of 27 July/August 2003 ADCP Survey Volume Flux Summary Sv Sv Sv 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 of 27 Nares Strait Hydrography, Aug 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 of 27 XX XXX ADCP CT/CTD All recovered instruments have clean 3-year records X X X X X X

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

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

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

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

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

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

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

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

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

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

27 of 27 Maslowski NPS

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 of 27 NorthSouth