1. Numerical Modeling of ocean circulation over the continental shelf and beneath the ice shelves in the Amundsen Sea, Antarctica WAIS September 28, 2006

2. Courant Institute of Mathematical Sciences New York University New York, U.S.A. David Holland Adrian Jenkins British Antarctic Survey Natural Environment Research Council Cambridge, U.K. Stan Jacobs Lamont-Doherty Earth Observatory, Columbia University New York, U.S.A.

3. Supported by

4. Continental Shelf, Amundsen Sea

5. Ice Shelves, Amundsen Sea

6. Outline 1.Ice Pump 2.POLAIR 3.Model Domain 4.Sea-Ice Simulation 5.CDW Pathways 6.Melt Rates 7.Tides 8.Heat Budget 9.Sensitivity CDW

7. 1 Ice Pump Pressure-Dependent Freezing-Point

8. Polar Ocean Land Atmosphere Ice Regional (POLAIR) Model(l)ing System 2 POLAIR Schematic

9. 2 POLAIR Components Isopycnic-ocean modification/combination of MICOM/Higdon Thermodynamic-dynamic sea-ice icepycnic & cavitating fluid Thermodynamic ice-shelf viscous-sublayer Forced by daily wind & air temperature (NCEP) Applied to Amundsen Sea and Ice Shelves

10. 2 POLAIR Hardware/Software columbia@nasa

11. 3 Model Domain Geographic Orientation Red box - full model domain Yellow Box- sub model domain (for most of analysis)

12. 3 Model Domain BEDMAP Bathymetry

13. 3 Model Domain Updated Bathymetry Nitsche & Jacobs LDEO (in prep.)

14. 3 Model Domain Bathymetry

15. 3 Model Domain Ice Shelf Thickness

16. 4 Sea-Ice - Concentration (& Velocity) Black-Hatched is Land (i.e., Grounded Ice) Lite-Blue- Hatched is Ice Shelf (i.e., Floating Ice) Vector Arrows are sea-ice motion Color is Sea-Ice Concentration (red is lots; blue is little) Grey- Hatched is open-ocean surface (i.e., no sea ice)

17. 5 CDW Pathways Depth 0000 m Lite-Blue- Hatched is Ice Shelf (i.e., Floating Ice) Black-Hatched is Land (i.e., Grounded Ice) Color is Ocean Temperature (red is warm; blue is cold) Vector Arrows are ocean motion

18. 5 CDW Pathways Depth 0100 m

19. 5 CDW Pathways Depth 0200 m

20. 5 CDW Pathways Depth 0300 m

21. 5 CDW Pathways Depth 0400 m

22. 5 CDW Pathways Depth 0500 m

23. 6 Melt Rate Year 5; Big Domain

24. 6 Melt Rate Model Equilibration Y0 to Y10 Large Interseasonal Variability

25. 7 Tides Variation of Sea-Surface Height Cyclonic Coastal Kelvin Wave

26. 7 Tides Basal Melt Rate (Tidal Forcing OFF) Annual Mean Basal Melt Rate is 66 cm/a

27. 7 Tides Basal Melt Rate (Tidal Forcing ON) Annual Mean Basal Melt Rate is 83 cm/a 25% Increase

28. 8 Heat Budget Continental Shelf Area Mask

29. 8 Heat Budget Ice Shelf Cavity Mask

30. Land Continental Shelf CDW 8 Heat Budget Tally 62 TW60 TW1 TW 41 TW40 TW

31. 9 Sensitivity CDW CDW Amount

32. 9 Sensitivity CDW CDW Temperature

33. Next Activities Coriolis Table (Grenoble)

34. Small fraction (~5%) available ocean heat used for melting Conclusions Linear increase in melt rate with increase in CDW amount Non-linear increase in melt rate with increase in CDW temperature