A global ocean mesh to overcome the North Pole singularity

A semi-analytical method is presented for constructing a global orthogonal curvilinear ocean mesh which has no singularity point inside the computational domain since the mesh poles are moved to land points. The method involves defining an analytical set of mesh parallels in the stereographic polar plan, computing the associated set of mesh meridians, and projecting the resulting mesh onto the sphere. The set of mesh parallels proposed here is defined as a series of embedded circles. The resulting mesh presents no loss of continuity in either the mesh lines or the scale factors over the whole ocean domain, as the mesh is not a composite mesh. Thus, the Bering Strait can be opened without specific treatment. The equator is a mesh line, which provides a better numerical solution for equatorial dynamics. The resolution can be easily controlled through the definition of three analytical functions which can increase resolution and/or maintain a low ratio of anisotropy. The mesh has been implemented in the LODYC general circulation ocean model. Results of a semi-diagnostic simulation are shown.