The model outputs are of three types: the restart file, the output listing,
and the diagnostic output file(s). The restart file is used internally by the code when
the user wants to start the model with initial conditions defined by a
previous simulation. It contains all the information that is necessary in
order for there to be no changes in the model results (even at the computer
precision) between a run performed with several restarts and the same run
performed in one step. It should be noted that this requires that the restart file
contain two consecutive time steps for all the prognostic variables, and
that it is saved in the same binary format as the one used by the computer
that is to read it (in particular, 32 bits binary IEEE format must not be used for
The output listing and file(s) are predefined but should be checked
and eventually adapted to the user's needs. The output listing is stored in
file. The information is printed from within the code on the
logical unit . To locate these prints, use the UNIX command
"grep -i numout" in the source code directory.
By default, diagnostic output files are written in NetCDF format but an IEEE binary output format, called DIMG, can be choosen by defining key_ dimgout.
Since version 3.2, when defining key_ iomput, an I/O server has been added which provides more flexibility in the choice of the fields to be written as well as how the writing work is distributed over the processors in massively parallel computing. The complete description of the use of this I/O server is presented in the next section.
By default, if neither key_ iomput nor key_ dimgout are defined, NEMO produces NetCDF with the old IOIPSL library which has been kept for compatibility and its easy installation. However, the IOIPSL library is quite inefficient on parallel machines and, since version 3.2, many diagnostic options have been added presuming the use of key_ iomput. The usefulness of the default IOIPSL-based option is expected to reduce with each new release. If key_ iomput is not defined, output files and content are defined in the diawri.F90 module and contain mean (or instantaneous if key_ diainstant is defined) values over a regular period of nn_write time-steps (namelist parameter).
Old Model Output (default or key_ dimgout)
Gurvan Madec and the NEMO Team
NEMO European Consortium2017-02-17