3/14/20051/32 Coastal Processes and Arctic Climate Change Are they resolved? Do they matter? How do they scale? Andreas Münchow College of Marine Studies University of Delaware Collaborators: Drs. Falkner, Garvine, Melling, Weingartner

3/14/20052/32 Hypotheses/Conclusions Large, abrupt pulses of freshwater discharges do not disturb the thermohaline circulation substantially; Freshwater driven flows scale with the internal deformation radius L~10-km (“eddy” scale); Scaling implies small across-shore (~10-km) and long along-shore (~1000-km) correlation scales; “Measured” (and modeled) freshwater fluxes do not resolve relevant scales; Nares Strait mooring array designed to resolve the internal deformation radius, freshwater fluxes, and dynamics.

3/14/20053/32 Coastal Processes and Arctic Climate Change: 1.Insulation of the Arctic ice-cover from warm Atlantic water at depth, i.e., “maintenance of the Arctic halocline” 2.Arctic freshwater and the global thermohaline circulation (nonlinear, multiple equilibria) How to move water across sloping topography? global

3/14/20054/32 Hypotheses/Conclusions Large, abrupt pulses of freshwater discharges do not disturb the thermohaline circulation substantially;

3/14/20055/32 Today’s climate Greenland Ice Core Data oxygen isotopes  18 O ~  T temperature Figure from Alley et al. (2001) Climate of last 10,000 years appears most anomalous.  18 O COLD WARM

3/14/20056/32 Hysteresis Loop of Climate Change Overturning Circulation 100 mSv Rahmstorf (2000) Nonlinear response of thermohaline circulation to freshwater pertubations Caveats: Location of current climate? year duration Distance to convection sites Stommel (1961) COLD WARM

3/14/20057/32 Hysteresis Loop of Climate Change Overturning Circulation 100 mSv Rahmstorf (2000) Stommel (1961) COLD WARM Freshwater Flux Alley (2001)

3/14/20058/32 Freshwater Flux:  ∫ u(s-s 0 )/s 0 dA 0.1 Sv = 0.1  10 6 m 3 /s = 100 mSv = 3,150 km 3 /year Arctic Rivers Bering Strait Davis Strait Lena River Amazon River Lake Ontario Arctic Ice Volume Lake Agassiz* 110 mSv 70 mSv 100 mSv 17 mSv 200 mSv 9 mSv >1,000 mSv 3,800 km 3 /y 2,200 km 3 /y 3,000 km 3 /y 510 km 3 /y 6,300 km 3 /y 270 km 3 /y 30,000 km 3 >30,000 km 3 /y (*) glacial lake dammed by Laurentian ice sheet burst ~8200 BP (Barber et al., 1999, Nature)

3/14/20059/32 Today’s climate Younger Dryas Greenland Ice Core Data oxygen isotopes  18 O ~  T temperature Adapted from Alley et al. (2001) Climate of last 10,000 years appears most anomalous.  18 O COLD WARM Lake Agassiz discharge

3/14/200510/32 Hypotheses/Conclusions Large, abrupt pulses of freshwater discharges do not disturb the thermohaline circulation substantially; Freshwater driven flows scale with the internal deformation radius L (“eddy” scale); √∆  /  0 g D / f ~ 10 km   +∆  D f is Coriolis “force”

3/14/200511/32 “derived” velocity Nares Strait Hydrography, Aug Pics-AprilPics-August Density Temp. Salinity CanadaGreenland L L D view from Greenland across Nares Strait

3/14/200512/32 David Huntley (UDel) with “sonar” in Aug Velocity: Radars + Sonars Radars send and receive electromagnetic waves (radio, police) Sonars send and receives acoustic waves (sound, whales) Same physics.

3/14/200513/32    t0t0 t hrs eastwest Barrow Canyon Velocity Section: Synoptic velocity observation in Barrow Canyon, Alaska (view is to the south): The flow scales with the internal deformation radius, about 5-km. The flow is also unsteady. Münchow and Carmack (1996) DD L

3/14/200514/32 I II III Eddies in the Arctic Sept.-22, 2004 IIIIII USCGC Healy 75-kHz ADCP L D

3/14/200515/32 Interaction of wind- and buoyancy forced motions Salinity Fresh riverine water turns right at the coast. Münchow and Garvine (1993) L D

3/14/200516/32 Hypotheses/Conclusions Large, abrupt pulses of freshwater discharges do not disturb the thermohaline circulation substantially; Freshwater driven flows scale with the internal deformation radius L~10-km (“eddy” scale); Scaling implies short across- (~10- km) and long along-shore (~1000- km) correlation scales

3/14/200517/32 Ward Hunt Ice Shelf ~ 4 km 3 fresh water and unique ecosystem lost from dammed epishelf lake in Disraeli Fjord Mueller et al. (2003) crack Ice shelf Ellesmere Island Disraeli Fjord Arctic Ocean

3/14/200518/32 Ward Hunt Ice Shelf Nutt (1966): The drift of ice island WH-5

3/14/200519/32 Labrador Shelf Moving ice on the Labrador shelf indicates trapping of fresh water and ice on the shelf Hudson Strait LABRADOR NASA deep convection site winter 1997 (Pickart et al., 2002)

3/14/200520/32 North (cm/s) East (cm/s) Labrador Labrador Sea Time (hours) basin shelf freshsalty Velocity Depth Sal. Temp.warmcool cold Crossing the Labrador Current, July-23, 2003 southward eastward

3/14/200521/32 Hypotheses/ Conclusions Large, abrupt pulses of freshwater discharges do not disturb the thermohaline circulation substantially; Freshwater driven flows scale with the internal deformation radius L~10-km (“eddy” scale); Scaling implies small across-shore (~10-km) and long along-shore (~1000- km) correlation scales; “Measured” (and modeled) freshwater fluxes do not resolve relevant scales ??? ?? Chapman and Beardsley (1989) adapted by Khatiwala et al. (1999)

3/14/200522/32 Davis Strait 3-year Mean ~150-m ~300-m ~500-m with 95% confidence levels for speed and direction “Ross” data (Tan et al., 2005)

3/14/200523/32 Baffin Island Current West Greenland Current 1.5Sv 0.7Sv 2.3Sv   Velocity normal to Davis Strait mooring section: 3-year mean velocity (contours) over salinity (color) 3-year mean velocity minus 95% confidence 3-year mean velocity plus 95% confidence Volume flux: 1.5 ± 0.8 Sv Freshwater flux: 75 ± 38 mSv EOF Analyses

3/14/200524/32 Davis Strait Northward 150-m (“surface”) Annual harmonic + Semi-annual harmonic + record mean Baffin Island Current West Greenland Current

3/14/200525/32 Retreat of Jakobshavn Isbræ West-Greenland NASA/USGS Greenland Ice Sheet Baffin Bay 5-km

3/14/200526/32 Hypotheses/Conclusions Large, abrupt pulses of freshwater discharges do not disturb the thermohaline circulation substantially; Freshwater driven flows scale with the internal deformation radius L~10 km (“eddy” scale); Scaling implies short across-shore (~10-km) and long along- shore (~1000-km) correlation scales; “Measured” (and modeled) freshwater fluxes do not resolve relevant scales; Nares Strait mooring array designed to resolve the internal deformation radius, freshwater fluxes, and dynamics

3/14/200527/32 Canadian Archipelago Throughflow Study (CATS): NASA 2002/223 Petermann Glacier Humbold Glacier Arctic Ocean Greenland

3/14/200528/32

3/14/200529/32 Geostrophic current Kennedy Channel Hydrography, Aug Pics-AprilPics-August   S CanadaGreenland L L D D view from Greenland across Nares Strait

3/14/200530/32 Salinity s Velocity Freshwater Flux/unit area Nares Strait South (Kennedy Channel)  ∫ u(s-s 0 )/s 0 dA  ∫ u dA  

3/14/200531/32 Across-channel flow Along-channel flow 100-m * Pics-April Pics-August.html  Wind  

3/14/200532/32 Hypotheses/Conclusions Large, abrupt pulses of freshwater discharges do not disturb the thermohaline circulation substantially; Freshwater driven flows scale with the internal deformation radius L~10-km (“eddy” scale); Scaling implies small across-shore (~10-km) and long along-shore (~1000-km) correlation scales; “Measured” (and modeled) freshwater fluxes do not resolve relevant scales; Nares Strait mooring array designed to resolve the internal deformation radius, freshwater fluxes, and dynamics.