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## Grounding Line Dynamics

In Elmer/Ice, the dynamics of the grounding line is treated as a contact problem between the bedrock and the ice. We didn't use the floating hypothesis to determinate the GL position, neither we impose a Schoof type condition at the GL.

Many solvers and user functions are required to solve this complex problem. Here is a flowchart of the SIF file required to solve for the GL dynamics.

1. GroundedSolverInit: initialise the `GroundedMask` variable (+ 1 if grounded, - 1 if floating, 0 if on the grounding line (also grounded but allow to localise the GL))
2. {Compute the Normal vector only where the ice is grounded. This is done by setting `Compute Normal` to `False` for all boundaries, excepted at the bedrock where:
```ComputeNormal Condition = Variable GroundedMask
Real MATC "tx + 0.5"```

}

### References

Favier L., O. Gagliardini, G. Durand and T. Zwinger, 2012. A three-dimensional full Stokes model of the grounding line dynamics: effect of a pinning point beneath the ice shelf. The Cryosphere, 6, 101-112, doi:10.5194/tc-6-101-2012.

Durand G., O. Gagliardini, B. de Fleurian, T. Zwinger and E. Le Meur. 2009. Marine Ice-Sheet Dynamics: Hysteresis and Neutral Equilibrium, J. of Geophys. Res., Earth Surface, 114, F03009, doi:10.1029/2008JF001170. [pdf]

Durand G., O. Gagliardini, T. Zwinger, E. Le Meur and R.C.A. Hindmarsh, 2009. Full-Stokes modeling of marine ice-sheets: influence of the grid size., Annals of Glaciology, 50(52), p. 109-114.