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Thule domain

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JRowanJordan edited this page Feb 21, 2023 · 8 revisions

CalvingMIP uses a modified version of the Thule artificial ice sheet domain proposed by Hilmar Gudmundsson (described here).

A Matlab function for the bedrock bathymetry (B) for the Thule domain is given by;

R=800e3;
Bc=900; 
Bl=-2000; 
Ba=1100;  

function [B]=BedGeom(x,y,R,Bc,Bl,Ba)
rc=0;
r=sqrt(x.*x+y.*y);
theta=atan2(y,x);
l=R-cos(2*theta).*R/2;
a=Bc-(Bc-Bl)*(r-rc).^2./(R-rc).^2;
B=Ba*cos(3*pi*r./l)+a ;
end

This leads to a total domain size of approximately 2000 km by 2000 km. We deliberately do not make any prescriptions in regard to model resolution and leave this decision ultimately up to individual participants. As the bathymetry is mathematically defined as a continuous function it should be useable for a variety of model frameworks.

ThuleSurf

Fig.1 -Thule bathymetry

ThuleTop

Fig.2 - Top down view of Thule bathymetry

For ease of ues of the Thule domain we find it convienient to name some geographical features that arise due to the underlying bedrock bathymetry, As such we define the North and South Tsalal, East and West Sphinx and Caprona A, B, C and D ice shelves. We also definie the North and South Benett ridges as being the ridges in bedrock bathymetry located under the North and South Tsalal ice shelves respectively. Finally, we define the Halbrane A and B ice streams as those feeding into the North Tsalal ice shelf whilst Halbrane C and D feed into the South Tsalal ice shelf.

We also define eight different profiles for use in experiments, namely;

  • "Caprona A profile" for the Caprona A ice shelf between (-390 km, 0 km) and (-590 km, 450 km)

  • "Caprona B profile" for the Caprona B ice shelf between ( 390 km, 0 km) and ( 590 km, 450 km)

  • "Caprona C profile" for the Caprona C ice shelf between (-390 km, 0 km) and (-590 km, -450 km)

  • "Caprona D profile" for the Caprona D ice shelf between ( 390 km, 0 km) and ( 590 km, -450 km)

  • "Halbrane A profile" for the Halbrane A ice stream and North Tsalal ice shelf between (-150 km, 0 km) and (-150 km, 740 km)

  • "Halbrane B profile" for the Halbrane B ice stream and North Tsalal ice shelf between ( 150 km, 0 km) and ( 150 km, 740 km)

  • "Halbrane C profile" for the Halbrane C ice stream and South Tsalal ice shelf between (-150 km, 0 km) and (-150 km, -740 km)

  • "Halbrane D profile" for the Halbrane D ice stream and South Tsalal ice shelf between ( 150 km, 0 km) and ( 150 km, -740 km)

Thule_Schematic

Fig.3 - Schematic representation of the Thule Ice Sheet. The zero elevation of bedrock bathymetry is showin in blue, an imposed calving front position from Experiment 3 in red with experimental profiles shown in black. Geographical features have also been labelled.
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