Numerical Modeling of ocean circulation

over the continental shelf and

beneath the ice shelves

in the Amundsen Sea, Antarctica

WAISSeptember 28, 2006

Courant Institute of Mathematical

Sciences New York University

New York, U.S.A.

David Holland Adrian Jenkins British Antarctic SurveyNatural Environment Research CouncilCambridge, U.K.

Stan Jacobs Lamont-Doherty Earth

Observatory,Columbia UniversityNew York, U.S.A.

Supported by

Continental Shelf, Amundsen Sea

Ice Shelves, Amundsen Sea

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

1 Ice Pump Pressure-Dependent Freezing-Point

Polar Ocean Land Atmosphere Ice Regional (POLAIR)

Model(l)ing System

2 POLAIR Schematic

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

2 POLAIR Hardware/Software columbia@nasa

3 Model Domain Geographic Orientation

Red box - full model domain

Yellow Box- sub model domain (for most of analysis)

3 Model Domain BEDMAP Bathymetry

3 Model Domain Updated Bathymetry

Nitsche & Jacobs LDEO (in prep.)

3 Model Domain Bathymetry

3 Model Domain Ice Shelf Thickness

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)

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

5 CDW Pathways Depth 0100 m

5 CDW Pathways Depth 0200 m

5 CDW Pathways Depth 0300 m

5 CDW Pathways Depth 0400 m

5 CDW Pathways Depth 0500 m

6 Melt Rate Year 5; Big Domain

6 Melt Rate Model Equilibration Y0 to Y10

Large Interseasonal Variability

7 Tides Variation of Sea-Surface Height

Cyclonic Coastal Kelvin Wave

7 Tides Basal Melt Rate (Tidal Forcing OFF)

Annual Mean Basal Melt Rate is 66 cm/a

7 Tides Basal Melt Rate (Tidal Forcing

ON)

Annual Mean Basal Melt Rate is 83 cm/a

25% Increase

8 Heat Budget Continental Shelf Area Mask

8 Heat Budget Ice Shelf Cavity Mask

Land

Continental Shelf

CDW

8 Heat Budget Tally

62 TW

60 TW

1 TW

1 TW 41 TW

40 TW

9 Sensitivity CDW CDW Amount

9 Sensitivity CDW CDW Temperature

Next Activities Coriolis Table (Grenoble)

• 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