Write output and restarts in a configurable directory path

[aerorahul]

Is your feature request related to a problem? Please describe.
NCEP/EE2 standards require restart capabilities for the forecast model.
After several discussions w/ NCEP Central Ops during the HAFSv3 implementation process, a run directory structure was co-developed. To enable/refine this restart feature, the model components would require to write their restarts and output to sub-directories instead of at the run directory root level.
Doing so has several advantages:

• At long forecast hours, the output volume overwhelms the run directory and saving output in a component specific sub-directory will aid in better organizing data and diagnosing issues in the event of model failures
• The workflows can redirect these output to a common path allowing restart capabilities from failure to continue.
• WW3 output will be consistent w/ other components e.g. MOM6 and CICE6 that allow placing their output in similar sub-directories MOM6_OUTPUT/ and CICE_OUTPUT/. These paths are namelist controlled and the defaults are ./

Describe the solution you'd like
WW3 output and restarts are written out to WW3_OUTPUT/ and WW3_RESTART/ (or equivalent) subdirectories. The path to these subdirectories could be namelist configurable.

Describe alternatives you've considered
None that have all the advantages outlined in the feature request.

Additional context
A ticket for GFSv16 was opened during v16 implementation #219

[BinLiu-NOAA]

@aerorahul Thanks for initial/creating this issue. This feature will be very useful for HAFS application/workflow (I am sure for other applications as well). Thanks!

[JessicaMeixner-NOAA]

Please note this work was already planned. The timeline for completion is 4-6 weeks.

[JessicaMeixner-NOAA]

@aerorahul any idea on how long of a directory file path length we should prepare for?

[aerorahul]

@aerorahul any idea on how long of a directory file path length we should prepare for?

I would imagine a directory_path of 512 characters should be sufficient based on long usernames and typical partition paths that are seen on systems.
The filename could be different (based on the typical names of files in WW3).
The result: directory_path/filename
HTH's

[JessicaMeixner-NOAA]

Thanks @aerorahul I'll plan for that and we can adjust as needed.