bug: obs_diag_streamflow

🐛 🐛 🐨

Describe the bug

1. Run obs_diag with wrf_hyrdo obs_seq.finals with SNOW_THICKNESS
2. What was the expected outcome? Successful run of obs_diag
3. What actually happened?
   Errors out with message about NC_UNLIMITED size already in use.

Error Message

 ERROR FROM:
  source : netcdf_utilities_mod.f90
  routine: WriteNetCDF
  message: types:def_dim obs_diag_output.nc: NetCDF: NC_UNLIMITED size already i
 n use
  message: ...

Which model(s) are you working with?

wrf_hydro

Version of DART

Which version of DART are you using?
Reported with v9.9.0-637-g654607621
Reproduced with v9.13.2

Have you modified the DART code?

Yes - v9.9.0-637-g654607621 has the fix for bug: #323
v9.13.2 nope.

Build information

Please describe:

1. Cheyenne
2. intel

Suspected cause

The error is happening because streamflow_obs_diag.f90 has a local max_defined_types that is undefined

86 integer :: max_defined_types_of_obs

There is

 550     max_defined_types_of_obs = lookup_flavor(flavor)

but this is in an if statement that is not entered.

So when you get to the netcdf writing:

max_defined_types_of_obs           0 NF90_UNLIMITED           0

so for this line:

call nc_check(nf90_def_dim(ncid=ncid, &
          name='obstypes', len=max_defined_types_of_obs, dimid=TypesDimID), &
          'WriteNetCDF', 'types:def_dim '//trim(fname))

Netcdf thinks you are defining the unlimited dimension again.

The 3D sphere obs_diag obs_kind_mod::max_defined_types_of_obs. I'm not sure at the moment why streamflow_obs_diag has a local max_defined_types_of_obs

"! All streamflow observations are identity observations at this point" is not true right?

         ! Check to see if it is an identity observation.
-         ! All streamflow observations are identity observations at this point
         if (flavor < 0) then

            ! Not every model location has a streamflow observation, but the
            ! location can be anywhere in the model state, so the 'flavor' can
            ! be quite large. We cannot allocate that much space, so we create
            ! a lookup array  ....

-           max_defined_types_of_obs = lookup_flavor(flavor)  !HK max_defined_types_of_obs  is unset for real obs.

            if (flavor > num_obs_types) then
               write(string1,*)'unsupported identity observation ',-1*flavor
               write(string2,*)'Increase "num_obs_types" and recompile.'
               call error_handler(E_ERR, 'obs_diag', string1, source, text2=string2)
            endif

            obsname = 'STREAM_FLOW'
            Nidentity = Nidentity + 1
         endif

Reproduce the failure by running obs_diag with the wrf_hydro obs_seq.finals input and SNOW_THICKNESS. Read streamflow_obs_diag.f90 around the local max_defined_types_of_obs declaration and its lookup_flavor assignment, then inspect netcdf_utilities_mod.f90:WriteNetCDF. Done means the run completes without the NC_UNLIMITED size-already-in-use error.