5.1. BASIN#

Create a configuration directory:
```
mkdir ~/CONFIGS/BASIN
```

Copy the input files for compilation from croco sources:

cd ~/CONFIGS/BASIN
cp ~/croco/croco/OCEAN/cppdefs.h .
cp ~/croco/croco/OCEAN/param.h .
cp ~/croco/croco/OCEAN/jobcomp .

Edit cppdefs.h for using BASIN case

# define BASIN

# undef REGIONAL

  You can also explore the CPP options selected for BASIN case.

  You can check the BASIN settings in ``param.h``.

Edit the compilation script jobcomp:

# set source, compilation and run directories
#
SOURCE=~/croco/croco/OCEAN
SCRDIR=./Compile
RUNDIR=`pwd`
ROOT_DIR=$SOURCE/..
#
# determine operating system
#
OS=`uname`
echo "OPERATING SYSTEM IS: $OS"

#
# compiler options
#
FC=$FC

#
# set MPI directories if needed
#
MPIF90=$MPIF90
MPIDIR=$(dirname $(dirname $(which $MPIF90) ))
MPILIB="-L$MPIDIR/lib -lmpi -limf -lm"
MPIINC="-I$MPIDIR/include"

# set NETCDF directories
#
#-----------------------------------------------------------
# Use :
#-lnetcdf           : version netcdf-3.6.3                --
#-lnetcdff -lnetcdf : version netcdf-4.1.2                --
#-lnetcdff          : version netcdf-fortran-4.2-gfortran --
#-----------------------------------------------------------
#
#NETCDFLIB="-L/usr/local/lib -lnetcdf"
#NETCDFINC="-I/usr/local/include"
NETCDFLIB=$(nf-config --flibs)
NETCDFINC=-I$(nf-config --includedir)

Compile the model:
- By using classical launch command (on individual computers):
```
./jobcomp > jobcomp.log
```
- OR by using a batch script (e.g. PBS) to launch the model (in clusters): For DATARMOR:
```
cp $CROCO_DIR/job_comp_datarmor.pbs .
qsub job_comp_datarmor.pbs
```
If compilation is successful, you should have a croco executable in your directory.

You will also find a Compile directory containing the model source files:
- .F files: original model source files that have been copied from $croco/OCEAN
- _.f files: pre-compiled files in which only parts defined by cpp-keys are kept
- .o object files
Copy the namelist input file for BASIN case:
```
cp ~/croco/croco/TEST_CASES/croco.in.Basin croco.in
```
Eventually edit it.

Run the model:

./croco croco.in > croco.out

If your run is successful you should obtain the following files:

basin_rst.nc # restart file
basin_his.nc # instantaneous output file

Have a look at the results:
```
ncview basin_his.nc
```
Test: some questions:
- What is the size of the grid (see param.h)?
- What are the name of the horizontal directions?
- What is the spatial resolution in both horizontal directions?
- How many vertical levels do you have?
- How are the vertical levels distributed (look for the cpp key NEW_S_COORD)?
- What are the initial dynamical conditions (see both cppdefs.h and croco.in)?
- What do the air-sea exchanges look like?
Re-run this case in parallel on 4 CPUs:

To run in parallel, your first need to edit cppdefs.h, param.h, and to recompile.
- Edit cppdefs.h:
```
# define MPI
```
- Edit param.h:
```
#ifdef MPI
integer NP_XI, NP_ETA, NNODES
parameter (NP_XI=2,  NP_ETA=2,  NNODES=NP_XI*NP_ETA)
parameter (NPP=1)
parameter (NSUB_X=1, NSUB_E=1)
```
Note

MPI tiles should be at least 20x20 points.
- Recompile.
- Run the model in parallel:
  - By using classical launch command (on individual computers):
    mpirun -np NPROCS croco croco.in
    where NPROCS is the number of CPUs you want to allocate. mpirun -np NPROCS is a typical mpi command, but it may be adjusted to your MPI compiler and machine settings.
  - OR by using a batch script (e.g. PBS) to launch the model (in clusters), examples are provided:
    cp ~/croco/croco_tools/job_croco_mpi.pbs .
  Edit job_croco_mpi.pbs according to your MPI settings in param.h and launch the run:
```
qsub job_croco_mpi.pbs
```
Warning

NPROCS needs to be consistent to what you indicated in param.h during compilation