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HYCOM-CICE-compilation.md

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The compilation of the nersc-hycom-cice model is handled by the compile script, simply called compile_model.sh, located in $NHCROOT/bin. This script does a lot of things "behind the carpet", so here is a quick description of what it actually does.

The compile script has to be run in the experiment dir, and a local directory "build" will be created that contains a copy of the source code (copied from $NHCROOT/hycom/RELO/). Its inside this directory that the compilation of the code takes place and final executable will be located.

Invocation of compile_model.sh

Running the compile_model.sh script without arguments will provide you with a brief description of how to run it. Here is the short version:

  Example:
     $(basename $0) [ -u ]  [ -m mpi_library ]  compiler

  arguments   :
     compiler : compiler to use for. Currently supported: ifort gfortran pgi

  optional arguments :
     -u              : update code in build dir from $sourcedir
     -m mpi_library  : on some machines you need to specify what mpi library to use

The only necessary argument is the compiler to use. Accepted values are pgi, gfortran, intel. The compile script needs this to choose the correct macro files when compiling the model.

The optional argument "-u" will make sure that you copy the most recent code from the $NHCROOT/hycom/RELO/ directory into the local build directory. If you run without the "-u" option, you will make no changes to the source code inside the build directory. (This is useful if you make local changes and want to keep them before possibly copying these changes to the "main" directory at $NHCROOT/hycom/RELO/).

The last optional argument "-m" determines what openmpi framework to use. On hexagon (and meny other big HPC installations), the openmpi framework is set by loading modules, so this argument is not needed in this case. On a mopre "generic" system, such as your local linux installation, you will have to specify what mpi framework to use (typical values are mpich, mpich2, openmpi, lam, intempi, etc etc).... The compile script needs this information mainly to choose the correct location of ESMF fortran modules when compiling the model.

compile_models.sh, step by step

Initial stuff...

Initially, the compile scripts set somelocal variables, such as ARCH (architecture) and SITE /(sitename) using the linux uname command.

Using these variables, a MACROID variable is set. This variable is used for getting the correct Makefile macros when compiling the HYCOM and COCE model code.

ESMF setup

Next, the compile script tries to get the location of the ESMF libraries and the ESMF include files. Three variables will be set (these are used in the makefile macros). The variables are

Variable Description
ESMF_DIR Top-level directory of the ESMF installation
ESMF_LIB_DIR Directory of the ESMF library
ESMF_MOD_DIR Directory of the ESMF fortran modules

Three cases arise:

  • If you have set ESMF_DIR, ESMF_MOD_DIR and ESMF_LIB_DIR before callign the compile script, then these will be used as they are.

  • Hardcoded cases (only hexagon for now) set ESMF_MOD_DIR and ESMF_LIB_DIR based on ESMF_DIR

  • Generic cases set ESMF_MOD_DIR and ESMF_LIB_DIR based on ESMF_DIR and the mpi library you use.

Source from EXPT.src

From the experiment source file (EXPT.src), the script will get equation of state to use, based on the variable SIGVER. It also sets the number of terms used by the equation of state.

copy code from $NHCROOT/hycom/RELO/

If the build dir does not exist, then an rsync command is run to get the HYCOM and CICE code from $NHCROOT/hycom/RELO/. If the directory does exist, no code will be copied unless tyhe "-u" option is provided to the script.

hycom_feature_flag

It is possible to specify hycom preprocessor flags inside this file to activate or deactivate features in the hycom code. If the file exists, it will be read and passed on to the C preprocessor command.

Set up eq of state

The equation of state will be set up next, and linked to the correct statement function based on the choice of SIGVER. This include file is needed when compiling hycom.

Compile CICE

The compilation of CICE then follows, using variables set up earlier in the script. Note that the grid size needs to be passed to CICE at this stage.

Compile HYCOM

The final step is to compile the HYCOM source code. This also compiles the main hycom-cice executable, and links the CICE and HYCOM object files to create the hycom_cice executable.