[MITgcm-support] MNC usage comment & more powerful version of gluemnc

[Mark Hadfield]

I'm trying to set up some reasonably large model runs with MNC output. 
It's not clear to me how to arrange things for efficient management of 
the output files and I'd appreciate some advice.

It seems to be a fundamental design decision of the MNC package that it 
will not overwrite existing netCDF files. This seems a little odd to me, 
but there you go.

OK, so I am running the model in two segments, the second being started 
from the pickup files of the first. If I set MNC_USE_OUTDIR to .FALSE. 
then the second run fails when trying to write monitor_grid files, so I 
set MNC_USE_OUTDIR to .TRUE. and MNC_OUTDIR_DATE to .FALSE. and I get my 
netCDF output in a bunch of directories, one per processor per model 
run. These happen to be 72-processor MPI runs, so the two model runs 
generate 144 directories.

At the end I want to combine all the state files from these runs, so I 
cd to the parent of the MNC output directories and type

gluemnc mncout*/state*.nc

This fails because gluemnc can't handle input file names with directory 
separators in them. I have hacked gluemnc to avoid this limitation. This 
hacking involved liberal use of the basename command and I *think* it's 
working OK now.

But this all seems awfully hard. Am I doing it wrong? Is there an easier 
way of setting these things up?

-- 
Mark Hadfield          "Ka puwaha te tai nei, Hoea tahi tatou"
m.hadfield at niwa.co.nz
National Institute for Water and Atmospheric Research (NIWA)