Blatter-Pattyn model

The Blatter-Pattyn model is given by

where u and v are the depth-independent x and y components of velocity, $\bar{\eta }$ is the depth-averaged effective viscosity, H is the ice thickness, ρ is the ice density, g is the acceleration due to gravity, and s=s(x,y) is the ice surface elevation.

Notice the symmetry in the equations. This means that, computationally, many of the same subroutines can be used for discretization.