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MPAS-Dev / MPAS-Model

Repository for MPAS models and shared framework releases.
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Introduce "invariant stream" capability to MPAS-Atmosphere #1137

Closed mgduda closed 7 months ago

mgduda commented 7 months ago

This PR introduces the capability to store time-invariant fields in a separate file, thereby avoiding the need to store copies of these fields in every time-varying initial conditions or restart file.

Without any changes in workflow, MPAS-A will appear to a user to work as before. However, if a definition of the "invariant" input stream is added to the streams.atmosphere file at runtime, and if the input_interval is set to "initial_only", e.g.,

<immutable_stream name="invariant"
                  type="input"
                  filename_template="x1.40962.L32.invariant.nc"
                  input_interval="initial_only" />

, the model will read all time-invariant fields from the designated file when starting up -- either from a cold-start or a restart; additionally, when restart files are periodically written during a simulation, time-invariant fields will be omitted from those restart output streams.

A file containing time-invariant fields can be produced while running the init_atmosphere_model program by setting config_vertical_grid = true while also setting config_met_interp = false in the namelist.init_atmosphere file for the real-data initialization case (init case 7). The invariant file can be used as input to the init_atmosphere_model program when interpolating real-data ICs with config_met_interp = true, and this same invariant file is suitable for use in the "invariant" stream in the streams.atmosphere file.