Using the 1D version of the Venus PCM (rcm1d)

One can run a single-column version of the Venus PCM. This is the rcm1d main program which simply uses the same physics as the 3D PCM but without dynamics, and for a single column. Very useful for some studies and when debugging or developing parametrizations.

Compilation

The main program rcm1d is compiled using the same compilation script, makelmdz_fcm, as for the 3D Venus 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.
• Even though the 1d-column version does not need to be run in parallel it should be compiled with option "-parallel mpi" because its outputs are managed by XIOS which requires being compiled with an MPI library (and hence the model should also be compiled with option "-io xios")

So for instance to compile a case for 78 vertical levels one would run something like:

makelmdz_fcm -arch somearch -p venus -d 78 -parallel mpi -io xios rcm1d

which would generate executable rcm1d_78_phyvenus_para.e in the bin subdirectory.

Inputs

Like the gcm program, the rcm1d program needs some inputs to be able 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;
• physiq.def for the definition of parametrizations that the user wants the model to run with;
• run.def and gcm.def files for the run configuration, which are similar to the one for the 3D PCM but in fact mostly not used as parameters there essentially concern dynamics.
• rcm1d.def A dedicated ASCII file adapted to the 1D case. An example rcm1d.def file, is available in LMDZ.VENUS/deftank.

Note that unlike the gcm program, the rcm1d program can run without any initial conditions start files (start.nc and startphy.nc); running rcm1d is as simple as running any serial code, e.g. assuming the executable has been renamed rcm1d.e:

./rcm1d.e

As for the GCM all external input files (apart from start files) are required to be present and available.

Outputs

The rcm1d main program uses the same output system than the 3D PCM. Therefore all outputs are managed by XIOS via xml files in the same way as the GCM.