Restarts

[fjansson]

Restarts can either be scheduled in both models using their namelists, or produced on demand with interface functions. If restarts are scheduled in the namelists, note that the spin-up time should be added for Dales.

This is a wish list for restarts.

OpenIFS interface

• set restart time, patch namelist, option NFRRES, in &NAMRES. (Negative value is hours, positive value is number of steps). Note that the files are written at the start of the next step.
• function to immediately write restart file, if possible

Dales

• setting trestart when creating a Dales model in the coupler is currently broken, presumably due to work on the Dales interface. Suggest we fix this when migrating the coupler to the new version of the interface.

Short-term plan:

For Dales, use les.write_restart(). For OpenIFS, schedule restart at end of run manually, using namelist option NFRRES. Note that the files are written at the start of the next step. finalize() calls the the first half gcm time step function to ensure that the files get written.

[fjansson]

Restarts are now working, and provide exactly the same simulation trajectory as a run without restarts.
Differences from the above:

• The final extra half step is now an extra full step. The first step of a restarted run = call to CALPAR doesn't actually advance time, so there is a one step overlap.
• NFRRES in the openIFS namelist is patched from the number of steps requested on command line.

TODO:

• when patching namelist, make sure that the entry NRESTS is not present, as it changes the meaning of NFRRES and breaks our restarts.

• The newly added accumulated surface rain fields in Dales are not restored on restarts, but start again from 0.