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PLASIM

Gerneral Circulation Models Planet Simulator (PlaSim) and PUMA. These models are research models of intermediate complexity used in Meteorology and Earth Sciences.

Documentation

Manuals are located in:

• puma/doc for the PUMA model
• plasim/doc for the Planet Simulator

Installation

To build PlaSim using CMake:

mkdir build && cd build
cmake ..
make -j4
make install

The installation directory can be specified by adding the argument -DCMAKE_INSTALL_PREFIX=... to cmake.

Further options can be enabled/disabled:

• WITH_GUI (to display a diagnostic GUI while running, default OFF),
• WITH_LSG, WITH_COUPLER (compile and couple the LSG ocean model, default OFF),
• WITH_MPI (enable MPI for multiprocessor runs, default ON).

Further settings can be set using these variables:

• nlats (number of latitudes, default 32 64)
• nlevs (number of vertical levels, default 10 20)
• npros (number of processors, default 1 4, 1 if MPI is not enabled.).

These variables can be lists of multiple values, in which case a binary for each possible combination will be compiled.

For example, instead of cmake .. in the above, one can do

cmake -Dnlats=32 -Dnlevs=10 -DWITH_MPI=OFF ..

to compile a single binary.

Dependencies

On Fedora, install openmpi-devel for MPI and load it with module load mpi. For the postprocessor install netcdf-cxx4-devel

On Debian, install openmpi-bin and libopenmpi-dev for MPI. For the postprocessor install libnetcdf-c++4-devel.

Usage

Run the PlaSim command of the desired resolution and parallelism (for example, plasim_t21_l10_p1 for T21 horizontal spectral resolution with 10 vertical levels on one processor). Binaries compiled with MPI need to be run on the correct number of processors, e.g. through mpiexec -np 4 plasim_t21_l10_p4.

Some settings (run length and filenames for data and settings) can be set from the command line. Most settings are set by running PlaSim from a directory containing Fortran namelist files containing the model settings. Possible namelist files are:

• plasim_namelist
• miscmod_namelist
• fluxmod_namelist
• rainmod_namelist
• vegmod_namelist
• landmod_namelist
• radmod_namelist
• surfmod_namelist

Variables inside a namelist are specified by a sequence of key=value pairs in a group. Keys are case-insensitive. There must be at least one comma, space, tab or newline between variables. The namelist starts with &<group name> and ends with a single /. The namelist filename for module called mymod is mymod_namelist, containing a group name mymod_nl. For example, plasim_namelist could contain the following:

  &plasim_nl
   n_run_days = 5,
   n_run_steps = 0,
   n_run_months = 0,
   n_run_years = 0,
 /

Model parameters can also be controlled in this way. For example, the atmospheric carbon dioxide concentration can be set in radmod_namelist as follows:

&radmod_nl CO2=400 /

Settings in namelists override corresponding command line settings.

The run length can be set to either a number of days (with the -days argument or n_run_days in plasim_namelist), or to a number of years and months (with -months and -years, or n_run_years and n_run_years). If days is set it will override years and months settings. For example, a run set with 50 days and 1 month will finish after 50 days.

The output file is called plasim_output by default and can be specified with the command line argument -output _filename_. It can be converted into NetCDF using the srv2nc scipt or the postprocessor burn8.

The complete state of the model will be written to plasim_dump at the end of the run. This filename can be specified with the -dump option. This state can later be used to re-initialise the model with the -restart option. This can be useful to occassionally save model states in long runs. If the run is interrupted for any reason it can later be restarted from the state dump file.