API overview

ClimaCore is organized as one module per subsystem. A model is assembled from the bottom of this table up: a domain is meshed, the mesh gets a topology, the topology and a quadrature rule give a grid, a grid and a staggering give a space, and fields live on spaces.

Module	Provides
`Domains`	The continuous domain: intervals, rectangles, the sphere
`Meshes`	Element meshes: intervals, rectilinear planes, the equiangular cubed sphere
`Topologies`	Element connectivity, including distributed (MPI) topologies
`Geometry`	Coordinates, local geometry, covariant/contravariant/Cartesian vectors
`Quadratures`	Gauss–Lobatto–Legendre and Gauss–Legendre nodes and weights
`Grids`	Spectral-element, finite-difference, and extruded grids; the CG/DG switch
`CommonGrids`	Convenience constructors for the standard grids
`Spaces`	Function spaces on grids; center/face staggering; DSS
`CommonSpaces`	Convenience constructors for the standard spaces
`Fields`	`Field` and `FieldVector`, the data containers and state vectors
`DataLayouts`	The memory layouts behind fields
`Operators`	Spectral-element, finite-difference, and DG operators; tendency completion
`Limiters`	Quasi-monotone and mass-borrowing limiters
`Hypsography`	Terrain-following vertical coordinates
`MatrixFields`	Banded matrix fields and solvers for implicit vertical problems
`Remapping`	Interpolation between spaces and to latitude–longitude grids
`InputOutput`	HDF5 checkpoint writers and readers
`Utilities`	Half-integer indexing, caches, and other shared helpers
`DebugOnly`	Hooks for locating NaNs and mismatched spaces

Export conventions

Only Domains, Meshes, Geometry, Quadratures, DataLayouts, Limiters, MatrixFields, Remapping, CommonGrids, and CommonSpaces export names. Everything in Spaces, Grids, Operators, Fields, Topologies, Hypsography, and InputOutput is called with its module qualifier, as in Spaces.SpectralElementSpace2D or Operators.GradientC2F. The usual import line is

import ClimaCore: Domains, Meshes, Topologies, Spaces, Fields, Geometry, Operators

Naming conventions

Finite-difference operators name the staggering they map between: C2F from cell centers to faces, F2C from faces to centers.
Spectral-element operators take a form-type parameter: Divergence() is the strong form and Divergence{WeakForm}() the weak form, and likewise for Gradient and Curl.
A trailing ! marks a function that mutates its first argument.
The Galerkin discretization of a spectral-element grid is Grids.CG() or Grids.DG(); Spaces.discretization(space) reads it back.