Thanks SO Much for ALL the Data: The Amundsen Sea Sector Data Set: Applications with UMISM: Where...

Thanks SO Much for ALL the Data: The Amundsen Sea Sector Data Set:

Applications with UMISM: Where and How Much WATER? What WILL happen in the future?

Thanks SO Much for ALL the Data: The Amundsen Sea Sector Data Set:

Applications with UMISM: Where and How Much WATER? What WILL happen in the future?

James L Fastook

University of Maine

We thank the NSF, which has supported the development of this model over many years through several different grants.

James L Fastook

University of Maine

We thank the NSF, which has supported the development of this model over many years through several different grants.

BEDMAP vs AGASEA/BBAS*

Airborne Geophysical survey of the Amundsen Sea Embayment (Holt et al., 2006 & Vaughan et al., 2006)

Embedded ModelsEmbedded Models

● High-resolution, limited domain

– runs inside

● Low-resolution, larger domain model.

● Modeling the whole ice sheet allows margins to be internally generated.

– No need to specify flux or ice thickness along a boundary transecting an ice sheet.

● Specification of appropriate Boundary Conditions for limited-domain model, based on spatial and temporal interpolations of larger-domain model.

● High-resolution, limited domain

– runs inside

● Low-resolution, larger domain model.

● Modeling the whole ice sheet allows margins to be internally generated.

– No need to specify flux or ice thickness along a boundary transecting an ice sheet.

● Specification of appropriate Boundary Conditions for limited-domain model, based on spatial and temporal interpolations of larger-domain model.

Nested Grids: 16263 nodes, 40 km

Nested Grids: 9000 nodes, 10 km

Nested Grids: 10920 nodes, 5 km

Nested Grids: 6402 nodes, 5 km

Nested Grids: 9000 nodes, 10 km

Nested Grids: 10920 nodes, 5 km

Nested Grids: 6402 nodes, 5 km

Nested Grids: 10920 nodes, 5 km

Nested Grids: 6402 nodes, 5 km

Nested Grid: Summary & runtimes

Grid

Nodes

DeltaX

DeltaT

Steps

Time/step(s)

Time(hr)

A116263

40 10 4000

0.81 0.9

E1 9000

10 5 8000

0.80 1.8

F110920

5 140000

0.88 9.8

G1 6402

5 140000

0.54 6.0

Full36000

5 140000

2.9 (est) 32.0

Vostok Temperature Proxy

Area-growth and retreat

●

Volume-growth and retreat

●

Water Peak during retreat

●

Data (Rignot 2004) and Results

1

3

5

7

9

2

4

6

Data (Lang 2004) and Results

65

4

3

2

1

PIG: velocity

●

PIG: bed

●

PIG: thickness

●

PIG: water

●

PIG: velocity

●

Thwaites: velocity

●

Thwaites: bed

●

Thwaites: thickness

●

Thwaites: water

●

Thwaites: velocity

●

Growth and retreat: thickness

● See AGASEA:Thick ● Requires bandwidth, movies are large…● http://tulip.umcs.maine

.edu/~shamis/iweb/WAIS-2006/AGASEA%3AThick.html

Growth and retreat: velocity

● See AGASEA:Velo● Requires bandwidth, movies are large…● http://tulip.umcs.maine

.edu/~shamis/iweb/WAIS-2006/AGASEA%3AVelo.html

Growth and retreat: water

● See AGASEA:Water● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-2

006/AGASEA%3AWater.html

Thwaites: thickness

● See Thwaites:Thick● Requires bandwidth, movies are large…● http://tulip.umcs.maine

.edu/~shamis/iweb/WAIS-2006/Thwaites%3AThick.html

Thwaites: velocity

● See Thwaites:Velo● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-2

006/Thwaites%3AVelo.html

Thwaites: water

● See Thwaites:Water● Requires bandwidth, movies are large…● http://tulip.umcs.maine

.edu/~shamis/iweb/WAIS-2006/Thwaites%3AWater.html

PIG: Thickness

● See PIG:Thick● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-

2006/PIG%3AThick.html

PIG: velocity

● See PIG:Velo● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-

2006/PIG%3AVelo.html

PIG: water

● See PIG:Water● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-

2006/PIG%3AWater.html

Future Retreat ScenariosFuture Retreat Scenarios

● Beginning with end of glacial cycle

– Run 100 years with conditions that produced present grounding line position.

– Then 1900 years with 1.00 Weertman thinning at grounding line wherever the bed is below 550 m.

● Beginning with end of glacial cycle

– Run 100 years with conditions that produced present grounding line position.

– Then 1900 years with 1.00 Weertman thinning at grounding line wherever the bed is below 550 m.

Weertman Parameter

●

Future Retreat ScenariosFuture Retreat Scenarios

● Beginning with end of glacial cycle

– Run 100 years with conditions that produced present grounding line position.

– Then 1900 years with 1.00 Weertman thinning at grounding line wherever the bed is below 550 m.

● Two Cases:

1. Condition is applied everywhere.

• Ross and Filchner-Ronne, as well as East Antarctica.

2. Condition is only applied in Amundsen Sea Sector.

• Two distinct patterns of retreat emerge for these two cases.

● Beginning with end of glacial cycle

– Run 100 years with conditions that produced present grounding line position.

– Then 1900 years with 1.00 Weertman thinning at grounding line wherever the bed is below 550 m.

● Two Cases:

1. Condition is applied everywhere.

• Ross and Filchner-Ronne, as well as East Antarctica.

2. Condition is only applied in Amundsen Sea Sector.

• Two distinct patterns of retreat emerge for these two cases.

Case 1: thickness

● See Case 1:Thick● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-

2006/Case 1%3AThick.html

Case 1: velocity

● See Case 1:Velo● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-

2006/Case 1%3AVelo.html

Case 1: water

● See Case 1:Water● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-

2006/Case 1%3AWater.html

Case 2: thickness

● See Case 2:Thick● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-

2006/Case 2%3AThick.html

Case 2: velocity

● See Case 2:Velo● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-

2006/Case 2%3AVelo.html

Case 2: water

● See Case 2:Water● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-

2006/Case 2%3AWater.html

Future: water percent & volume

●

1. Conclusions: Past cycle1. Conclusions: Past cycle

• From a modeler’s perspective the new data set is great.

• The nested, embedded model captures the salient features of the Amundsen Sea Sector velocity field.

• The water system is

- dendritic, - follows bed topography, - appears to be decreasing in area as the present

is approached, - with peak water volumes during or just prior to

periods of retreat.

• From a modeler’s perspective the new data set is great.

• The nested, embedded model captures the salient features of the Amundsen Sea Sector velocity field.

• The water system is

- dendritic, - follows bed topography, - appears to be decreasing in area as the present

is approached, - with peak water volumes during or just prior to

periods of retreat.

2. Conclusions: Future retreat2. Conclusions: Future retreat

• Retreat scenarios depend strongly on whether grounding-line thinning is confined to the Amundsen Sector (Case 2) or involve the Ross and Filchner-Ronne too (Case 1).

• In Case 1, retreat is much faster and more extensive, and comes in from behind the Amundsen Sea Sector.

• Case 2 looks more like the classic “weak underbelly” with retreat in Thwaites and up the PIG with a non-smooth episodic retreat punctuated by pulses of water production that seem to precede retreat steps.

• Retreat scenarios depend strongly on whether grounding-line thinning is confined to the Amundsen Sector (Case 2) or involve the Ross and Filchner-Ronne too (Case 1).

• In Case 1, retreat is much faster and more extensive, and comes in from behind the Amundsen Sea Sector.

• Case 2 looks more like the classic “weak underbelly” with retreat in Thwaites and up the PIG with a non-smooth episodic retreat punctuated by pulses of water production that seem to precede retreat steps.

Case 1: Rate

● Case 1:Rate● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-

2006/Case 1%3ARate.html

Case 2: Rate

● See Case 2:Rate● Requires bandwidth, movies are large…● http://tulip.umcs.maine.edu/~shamis/iweb/WAIS-

2006/Case 2%3ARate.html