4.4. Glossary

cap: A NUOPC-compliant software layer between a component’s native code and the mediator, presenting the component to the coupled system through import and export states. See Core concepts.
CDEPS: The Community Data Models for Earth Prediction Systems — data components (DATM, DOCN, …) that can replace an active component, for example by replaying saved coupler forcing (see the histaux discussion in History output).
component: A model of one part of the Earth system — atmosphere (atm), ocean (ocn), sea ice (ice), land (lnd), river (rof), wave (wav) or land-ice (glc).
coupling interval: The period between successive couplings of a component, set by the <COMP>_NCPL settings and reflected in the run sequence. See Configuring and running a case (CESM/NorESM).
driver: The top-level NUOPC application component that harnesses the mediator and the component models and runs the coupled time loop. It is host-specific, unlike the shared mediator. See Core concepts.
exchange grid: An ESMF grid formed from the overlap of two component grids, on which atmosphere/ocean fluxes may be computed. See Atmosphere/ocean fluxes.
FBExp: The internal-state field bundle holding the fields the mediator exports to a component. See Code organization.
FBImp: The internal-state matrix of field bundles FBImp(n,k) — component n’s fields on grid k. See Code organization.
field dictionary: The per-host YAML file (fd_<host>.yaml) defining the standard names, units and metadata of the coupled fields. See Fields and the field dictionary.
fraction: The fraction of a surface type (land, ocean, sea ice) in a grid cell, used as a weight in merges and mappings. See Surface fractions.
histaux: Auxiliary coupler history streams that record the fields a source component sends into the mediator, for reuse as forcing via CDEPS. See History output.
mapping: Interpolation of a field from a source grid to a destination grid through an ESMF routehandle. See Mapping.
mediator: The CMEPS component that couples the component models — mapping, merging, computing fluxes and albedos, and maintaining fractions. Shared across host applications.
merging: Combining one or more mapped source fields into a single destination field. See Merging.
phase: A named routine the mediator registers with NUOPC and that the run sequence invokes (for example med_phases_prep_ocn). See The phase lifecycle.
routehandle: A precomputed sparse-matrix set of interpolation weights used to apply a mapping. See Mapping.
run configuration: The host-specific file (nuopc.runconfig for CESM/NorESM, ufs.configure for UFS) supplying the attributes the driver and mediator read. See NUOPC attributes (CESM/NorESM).
run sequence: The ordered recipe of component runs, mediator phases and field transfers, with their coupling intervals, that the driver ingests. See The run sequence.