Getting Started

Getting Started

ROMS is a very complex model with many options and capabilities. ROMS is composed of many Fortran files (.F), a few header files (.h), various input script files (.in), a metadata variable definition file (varinfo.yaml), and a single makefile. The ROMS algorithms are distributed with the following directory structure:

Compilers/                     make configuration files
Data/                          Input data root directory
    /ROMS/                     ROMS data root directory
         /CDL                  ROMS NetCDF metadata design
Master/                        Main standalone and coupling programs
ROMS/                          ROMS root directory
    /Adjoint/                  Adjoint model
            /Biology           Adjoint biology/ecosystem models
    /Bin                       Executable scripts
    /Drivers                   Computational drivers
    /External                  Standard input scripts
    /Functionals               Analytical expression header files
    /Include                   Test cases configuration header files
    /Modules                   Declaration modules
    /Nonlinear/                Nonlinear model
              /BBL             Bottom Boundary Layer formulation
              /Biology         Nonlinear biology/ecosystem models
              /SeaIce          SeaIce model
              /Sediment        Nonlinear sediment transport model
    /Obsolete                  Discontinued files
    /Programs                  Support programs
    /Representer/              Representer model
                /Biology       Representer biology/ecosystem models
    /Tangent/                  Tangent linear model
            /Biology           Tangent linear biology/ecosystem models
    /Utility                   Generic utility files
User/                          ROMS User interface root directory
    /External                  User standard input scripts
    /Functionals               User analytical expressions templates
    /Include                   User application header files

ROMS uses C-preprocessing extensively to activate and/or deactivate the various numerical and physical algorithm options. It also uses NetCDF to manage input and output data streams. It is highly recommended that first time users learn the basics of NetCDF before working with ROMS.

Basic Steps

• Register at the ROMS website (www.myroms.org) to get access to the algorithms and other user privileges. Select a username and password which will be used in the future to login and post messages on the ROMS forum, algorithm downloads, and contributing to wikiROMS.

• Make sure that you have the following required software in your computer before attempting to compile and run an application:
  • Git client to download source
  • Fortran 90 or Fortran 95 compiler
  • cpp program for C-preprocessing ROMS source code.
  • GNU make version 3.81 or higher to compile ROMS
  • Perl interpreter program
  • NetCDF library, with Fortran 90 interface
  • Message Passing Interface (MPI) library to run in parallel on a distributed-memory system

• Use a Git client to clone the latest version of the ROMS develop branch. It is highly recommended that you obtain the code on the same system that you will be compiling and running the code on to avoid file format issues.

• We recommend that you use the included build script to compile and link ROMS. This will set up your build environment and execute the make command to build the default ROMS upwelling application. This process allows you to avoid editing the makefile. Please visit the build script page for more detailed instructions.
  • You can also type make at the top of the directory structure where the makefile is located but we do not recommend this process because it requires changing the ROMS files which can cause conflicts when you update you ROMS code.

Note: To speed compilation, you may want to add the -j <n> flag to the build command (i.e. build.sh -j 4) where <n> is the number of processors you wish to compile with. Even single processor machines can benefit from the -j flag with <n> = 2.

Note: To make sure your application can compile successfully, you might want to set USE_DEBUG to on in the build script since it will compile faster. Once your application can compile you can unset USE_DEBUG in order to create an optimized executable. Please visit the build script page for more information

Note: In SVN revision 933 (January 26, 2019) all ocean_*.in files were renamed to roms_*.in and all ocean* ROMS executables were renamed to roms* in order to facilitate and clarify model coupling efforts. More information can be found in the ROMS repository Trac ticket #794. If you are working with a ROMS release prior to revision 933 you will need to replace roms_upwelling.in with ocean_upwelling.in and romsS, romsM, or romsO with oceanS, oceanM, or oceanO in all commands below.

• To run ROMS in serial, just type:
  romsS < ROMS/External/roms_upwelling.in > & log &
  or to run in parallel (distributed-memory) on two processors:
  mpirun -np 2 romsM ROMS/External/roms_upwelling.in > & log &
  or to run in parrallel (shared-memory) on two processors:
  setenv OMP_NUM_THREAD 2
  romsO < ROMS/External/roms_upwelling.in > & log &
  Here, the the file ROMS/External/roms_upwelling.in contains all the input parameters to required by this application. Visit roms.in for more information.

Notice that in distributed-memory, the leading < is omitted so all parallel threads can read and process this input script without any communications in between.