Difference between revisions of "Ice Sheet Evolution Experiments"

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(New page: We will now do some simple ice-sheet evolution experiments using the higher-order model and the 1st-order mass advection scheme we just created. By "simple", I mean coarse resolution, idea...)
 
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We will now do some simple ice-sheet evolution experiments using the higher-order model and the 1st-order mass advection scheme we just created. By "simple", I mean coarse resolution, idealized domains with idealized boundary conditions that are actually somewhat non-sensicle. In some sense, we just want to be able to convince ourselves that the combination of a higher-order velocity solution and a mass advection scheme, works.
 
  
In the first case, we will allow a parablic-shaped mound of ice to spread out under it's own weight. The non-sensicle part is that we will assume a fixed lateral boundary; the ice sheet margin won't be allowed to move past it's original position. Think of an ice sheet surrounded by a very tall (and very strong) fence. In map view, the ice sheet will eventually take on the shape of a disk of uniform thickness.
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Now that we've (1) convinced ourselves that the higher-order model is "working" (at least as well as other higher-order models out there) and (2) added some code so that we can evolve the ice sheet geometry, we can do some simple experiments looking at the combination of the two. By "simple", I mean coarse resolution, idealized domains with idealized boundary conditions. These may actually be somewhat "non-sensicle" with respect to real ice sheets, but that makes the output much more easy to analyze.
  
In the second case, we will evolve an ice shelf of uniform thickness and temperature, which is confined on three sides and open to the ocean on the fourth side. With no accumulation, which we'll assume, the only thing that can happen is that ice flows out of the shelf front. Eventually, the shelf should thin to zero thickness, but how and when that happens will vary depending on a number of things.
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The two experiments we will attempt are:
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# Allow a parablic-shaped mound of ice to spread out under it's own weight. The non-sensicle part is that we will assume (i) zero surface mass balance (no accumulation or ablation) and (ii) a fixed lateral boundary. That is, the ice sheet margin won't be allowed to move past it's original position (think of an ice sheet surrounded by a very tall (and very strong) fence - the ice sheet will eventually take on the shape of a disk with uniform thickness).
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# Evolve a confined ice shelf of uniform thickness and temperature for XX years (that is, we will evolve the diagnostic solution to the unpublished ESIMINT ice shelf experiments 3 and 4 [http://homepages.vub.ac.be/~phuybrec/eismint/iceshelf.html], which you [[COMSOL activities#Shallow shelf approximation|explored a bit earlier in one of the COMSOL exercises]]. The non-sensicle part here is that again, we assume no accumulation or ablation. Thus, the only thing that can happen is that ice flows out of the shelf front. Eventually, the shelf should thin to zero thickness (but how and when that happens will vary depending on a number of things).

Revision as of 09:56, 6 August 2009

Now that we've (1) convinced ourselves that the higher-order model is "working" (at least as well as other higher-order models out there) and (2) added some code so that we can evolve the ice sheet geometry, we can do some simple experiments looking at the combination of the two. By "simple", I mean coarse resolution, idealized domains with idealized boundary conditions. These may actually be somewhat "non-sensicle" with respect to real ice sheets, but that makes the output much more easy to analyze.


The two experiments we will attempt are:

  1. Allow a parablic-shaped mound of ice to spread out under it's own weight. The non-sensicle part is that we will assume (i) zero surface mass balance (no accumulation or ablation) and (ii) a fixed lateral boundary. That is, the ice sheet margin won't be allowed to move past it's original position (think of an ice sheet surrounded by a very tall (and very strong) fence - the ice sheet will eventually take on the shape of a disk with uniform thickness).
  2. Evolve a confined ice shelf of uniform thickness and temperature for XX years (that is, we will evolve the diagnostic solution to the unpublished ESIMINT ice shelf experiments 3 and 4 [1], which you explored a bit earlier in one of the COMSOL exercises. The non-sensicle part here is that again, we assume no accumulation or ablation. Thus, the only thing that can happen is that ice flows out of the shelf front. Eventually, the shelf should thin to zero thickness (but how and when that happens will vary depending on a number of things).