GENIE Gridspec Diagrams Boundary

Boundary contact regions occur where two grid tiles meet, but do not overlap. The boundary type below is suitable for grid tiles with logically-rectangular discretisations; it consists of:


 * An anchor point - a point common to both grid tiles;


 * An "alignment" flag, used to indicate whether the anchor point is shared in index space by both tiles;


 * An orientation, which can be used to indicate how vector fields are transformed as they cross the boundary - for instance, whether latitudes on the first grid tile map to latitudes or longitudes on the second grid tile;


 * A refinement, which describes whether grid lines (cell edges) are continuous between tiles, just continuous for the coarser tile, or coprime.



Note: the gridspec overview contains introductory and background information on the gridspec; more detailed information can be found in Balaji's gridspec document on the Earth System Curator website.