1. Do Physical Oceanographers Care About Coastal Processes in Water Less Than 20-m Deep?
Andreas Münchow, College of Marine Studies, University of Delaware
Fort Conger, Ellesmere Island, Aug. 2003
Roger Davis
12/12/04

2. Questions:
How does terrestial freshwater flux impact the thermohaline circulation and global climate?
Do large estuarine discharges form buoyancy-driven coastal currents?
How do upwelling favorable winds impact a large buoyant plume on the shelf?
What are the ambient shelf currents and how do the impact the large discharge?
12/12/04

3. Fronts as Convergence Zones:
river
shelf
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4. Rio de la Plata, Argentina
Horizontal Stratification,
large River Discharge
River Plume waters
Shelf Waters
Surface Front
Rio de la Plata, Argentina
12/12/04

5. Mississippi River Plume
Horizontal and Vertical Stratification,
Large River Discharge
Plume water
Shelf water
Mississippi River Plume
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6. Mackenzie River Plume:
clouds
ice
Note the
3 bands of
different color:
Sediment settling?
Biogeochemistry?
Pulsed discharge?
Stratification?
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7. Physical Oceanography:
Mass is conserved
density measurements
Momentum* is conserved
velocity measurements
(*) momentum=mass*velocity
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8. Mass: Hydrocast or CTD “old” style CTD (on-station)
“new” style CTD (underway)
12/12/04

9. Velocity: Radars + Sonars
Radars send and receive
electromagnetic waves (radio, police)
Sonars send and receives acoustic waves (sound, whales)
Same physics.
David Huntley with “sonar”
12/12/04

10. Surface drift currents (1-m) on the East Siberian Shelf Sea:
From Münchow et al. (1999)
12/12/04

11.  East Siberian Shelf coast ice edge Sloping isopycnals
suggest a flow, into the page, , or to the west
coast
ice edge
Temperature has little effect, impact, and is generally not useful
Note the correspondence of salinity and density, i.e., dynamics are dominate by an offshore source of freshwater.
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12. Upwelling on a shallow shelf
Temperature:
Cold bottom waters surface
Salinity:
Fresh coastal waters move offshore
Density:
Stratification changes rapidly
from Münchow and Chant (2000)
12/12/04

13. Surface currents from land-based HF radar
from Münchow and Chant (2000)
25k25km
Four characteristic flow patterns responding to wind and freshwater discharges
Modern radars get 80k80km
at the same 1-km resolution
12/12/04

14. Coastal Circulation off Barrow, Sept.-12, 2004
as measured by75-kHz acoustic Doppler current profiler
Flow is in the opposite direction from what is the canonical view of fresh Bering Sea water entering the Arctic via Barrow Canyon
12/12/04

15. Conclusions
Yes, physical oceanographers care about processes in shallow water
Arctic oceanography community often unaware of more advanced mid-latitude coastal oceanography
Physics crucial in understanding across-shore exchange processes including sediment transport
Advances in modern measuring technology slow to migrate into the Arctic community
12/12/04