Mesh generators

The mesh generators output mesh input files intended for use by LFRic applications. They generate 2D-mesh topologies comprised of faces (quadrilateral cells), edges and nodes elements.

Two separate generators are provided for the creation of either ‘’Cubed-Sphere’’ or ‘’Planar’’ meshes. Development of these tools is driven by application requirements on LFRic core infrastructure.

Output files are in NetCDF format following UGRID conventions [1]. While UGRID may describe the mesh topologies, this may not be sufficient for some use cases in LFRic applications. Where required, additional mesh information may be added using variable attributes on the mesh.

Cubed-Sphere mesh generator

Generates one (or more) 2D Cubed-Sphere meshes that each follow the base strategy.

• Six panels (1 per face of the cube), each of side n X n cells.

• Panels 1:4 band the equator, with Panel-1 centred on the null island [2].

• Panels 5 & 6 are centred on the North (90N,0E) and South (90S,0E) poles respectively.

–usage:

>> cubedsphere_mesh_generator <configuration.nml>

Planar mesh generator [3]

Generates one (or more) 2D gridded meshes that each follow the base strategy.

• Single panel of side n X m cells.

• Located using combination of the specified domain centre and extents.

• Axes aligned with <longitude>,<latitude> or <x>,<y>.

• Allows periodicity of oppposing domain boundaries to be set [4].

–usage:

>> planar_mesh_generator <configuration.nml>

Footnotes

[1]

NetCDF(.nc) file compliant with UGRID v1.0 convention.

[2]

Null Island: where the prime medridian and the equator intersect, i.e. 0N, 0E.

[3]

For historical reasons, the planar mesh generator is not restricted to a planar surface domain. References to planar meshes with respect the following sections should be taken as a mesh produced by the planar_mesh_generator program.

[4]

A pair of periodic domain boundaries are connected such, that where a field quantity exits the model domain crossing one of the boundaries, it re-enters the domain at the opposing domain boundary.