distortion effects of stereographic coordinate systems

[aaschwanden]

I'm posting this here as food for thought, as the discussion has come up at the ice sheet-climate interaction workshop in Reading UK, 9/30-10/2 2013.

For global, fully coupled paleo simulations, large part of the northern hemisphere becomes glaciated. Using the same polar-stereographic domain covering the northern for the ice sheet model leads to substantial distortions away from the poles, not only in volume calculations but in the momentum balance equations.

From an earth system model point of view it would be desirable to run the ice sheet model on a geographic lat/lon grid as well (with an appropriately rotated pole towards the equator). This is unlikely to happen for any existing ice sheet model.

However, we could evaluate the possibility to make the momentum calculations also lat/lon aware, that is, allowing dx and dy to vary. Correct me if I'm wrong: we're already doing this for area and volume calculations but not for the momentum balance.