Consider the future of grid specifications

[bnlawrence]

Currently we have gridspec, but it is not obvious that gridspec is the right kind of animal for the general software description of grids in simulation software descriptions. It might be a useful specialisation at some point, but higher level concepts appear to be necessary.

[bnlawrence]

W. Deconinck et al. / Computer Physics Communications 220 (2017) 188–204 in their figure 4 have a useful ontology of types of grids:

The paper itself needs reading (especially section 3.2), but this snippet gives a flavour of the important bits:

For convenience the above concrete grids can be retrieved by a short grid identifier, e.g. O1280, in which the number represents the number of parallels between the North Pole (90◦ latitude) and equator (0◦ latitude). The grid identifiers for the grid classes RegularLonLatGrid, RegularGaussianGrid, ClassicGaussianGrid and OctahedralGaussianGrid are respectively L#, F#, N# and O#. These grid identifiers provide a common language to uniquely reference a grid in terms of resolution and category.
The classification further envisions to incorporate grids like the IcosahedralGrid, the CubedSphereGrid, and the YinYangGrid [31], which can be seen as combinations of sub-grids. These grids inherit from a class StructuredZonesGrid as illustrated in Fig. 4.
Listing 1 details how one can create the grids shown in Fig. 5 using either a grid identifier as described previously, or a Config object containing enough information to construct the correct grid. Such Config object could be constructed using JavaScript Object Notation (JSON), either programmatically (from a string) or from a file. Internally a Factory design pattern [32] is responsible for instantiating the correct concrete grid implementation.

[bnlawrence]

It's a runtime configuration as to what the decomposition is ... so we need to think about having a sensible runtime configuration sitting inside the CIM as well ...

[bnlawrence]

See also the specialisations:

• CMIP6 atmosphere
• CMIP6 ocean
• CMIPO6 atmos-chem
• CMIP6 sea ice
• CMIP6 land ice