2.2. NUOPC attributes (CESM/NorESM)

This page covers the CESM/NorESM run configuration and the attributes the mediator obtains from it. For what a run configuration is and how it relates to the driver and the mediator, see Core concepts.

For CESM/NorESM the run configuration is the nuopc.runconfig file, which the driver ingests at start-up. As explained in the concepts, the mediator does not read this file directly — the driver ingests it and sets attributes on the components, and the mediator queries the attributes it needs.

Importantly, each component obtains its attributes at initialization through calls to NUOPC_CompAttributeGet. This is a general NUOPC mechanism, not specific to the mediator: the driver makes the run-configuration attributes available on every component, and each one — CMEPS and all of the model components in the coupled configuration — obtains the attributes it uses this way.

The file is organized into the component_list (the active components, e.g. MED ATM LND ICE OCN ROF GLC WAV), the run sequence runSeq:: block, and a set of ESMF attribute groups. Each group is written as <name>:: … :: and holds the attributes for a particular scope:

  • DRIVER_attributes — driver-level settings:

    • the model name

    • timing and log output paths

    • reproducible-sum options

    • the water-vapor saturation scheme

    • the coupler restart pointer (drv_restart_pointer)

  • PELAYOUT_attributes — the processor layout:

    • the task and thread counts, root PE and stride for each component (atm_ntasks, atm_rootpe, …)

    • the number of instances

    • asynchronous-PIO settings

  • ALLCOMP_attributes — attributes queried by every component, not just the mediator:

    • the orbital parameters (orb_*)

    • the scalar-field descriptors (ScalarField*) that describe the scalar values exchanged between each component and the mediator

    • the per-component model names (ATM_model, OCN_model, …)

    • the mesh mask, profiling, and other coupling-wide options

  • MED_attributes — the mediator’s own attributes, and by far the largest group. These are the attributes the mediator queries; they are detailed in Attributes the mediator queries below.

  • CLOCK_attributes — time-management attributes, also queried by every component:

    • the per-component coupling timesteps (atm_cpl_dt, ocn_cpl_dt, …)

    • the calendar

    • the start date and time

    • the stop and restart cadence (stop_*, read_restart)

  • ATM_attributes, ICE_attributes, GLC_attributes, LND_attributes, OCN_attributes, ROF_attributes, WAV_attributes — per-component attributes visible to the driver. Most hold little more than a verbosity level plus a few component-specific options (for example aqua_planet under ATM_attributes).

2.2.1. Attributes the mediator queries

During its initialization phases the mediator retrieves attributes with NUOPC_CompAttributeGet. Each lookup reports whether the attribute is present and set, so optional attributes can fall back to defaults. The attributes CMEPS consumes fall into a few groups:

  • Coupling mode — coupling_mode selects which host exchange logic (esmFldsExchange_<host>_mod.F90) and which custom prep calculations are used.

  • Atmosphere/ocean flux options — for example aoflux_grid (the grid on which the air-sea fluxes are computed) and ocn_surface_flux_scheme.

  • Diagnostics and budgets — for example do_budgets (enable the water and energy budget diagnostics).

  • Auxiliary history — the histaux_* settings for the mediator’s auxiliary history streams.

  • Debugging — for example dbug_flag and check_for_nans.

Most of these attributes are set for you by the compset and case configuration. Where you can change them yourself, it is through user_nl_cpl or xmlchange as described in Configuring and running a case (CESM/NorESM).

Note

The complete list of attributes CMEPS requires or recognizes — including which are required, which are optional, and which are specific to a particular host — is given in the Reference. This page orients you to the attributes the mediator queries; the Reference is the authoritative catalogue.