Generic unicolumn rcm1d program

It is possible to run the Gneric PCM in a uni-column (aka "single-column") configuration: this can be done via the rcm1d program; quite useful form some first studies but also when developing and testing parametrizations.

Compilation

The main program rcm1d is compiled using the same compilation script, makelmdz_fcm, as for the 3D Generic lon-lat PCM. Nevertheless, there are few modifications:

• the -d option requires only one argument, the number of vertical levels;
• the main program to compile is rcm1d rather than gcm.

So for instance to compile a case for 26 vertical levels one would run something like:

makelmdz_fcm -arch somearch -d 26 -p generic rcm1d

Note that it is possible to compile and run with the XIOS library, which will require compiling in "mpi" mode (required by XIOS), even though the run will be serial:

makelmdz_fcm -arch somearch -d 26 -p generic -parallel mpi -io xios rcm1d

Inputs

Just like the 3D GCM, the rcm1d program needs some inputs to run. The needed files are:

• z2sig.def for the definition of vertical levels;
• traceur.def for the definition of tracers that the user wants the model to run with;
• callphys.def for the definition of parametrizations that the user wants the model to run with;
• rcm1d.def for the run configuration, which is similar to the 3D run.def; see The rcm1d.def Input File. In practice the rcm1d.def file is in fact copied as run.def by the rcm1d program when it runs.

Unlike the 3D GCMs, the rcm1d program can run without any start files, which is its default (restart=.false.). In this setup, one can (and often needs) needs to provide initial profiles of each tracer. These consist in files called profile_sometracername containing column-wise the initial values of the considered tracer. Then, the first line corresponds to the surface tracer and the following lines correspond to the layers. At the end of a 1D simulation, rcm1d outputs a restart file restart1D.nc which can be used as an initial condition for a following run.

If restart=.true. in rcm1d.def then the program will look for start files start1D.nc and startfi.nc and use these as initial conditions.

Outputs

If compiled without XIOS then rcm1d will output diagfi.nc and stats.nc files, just like the 3D GCM and the optional diagfi.def and stats.def files can be respectively added to specify which variables need be outputted. Likewise if compiled with XIOS then rcm1d will output all files as specified in the relevant xml files, just like the 3D GCM.

As mentioned above, at the end of a simulation rcm1d also outputs a restart1D.nc file containing the final computed state.