\newpage
\chapter{The configuration file {\it namcouple}}
\label{sec_namcouple}

The OASIS3-MCT configuration file {\it namcouple} contains, below
pre-defined keywords, all user's defined information necessary to
configure a particular coupled run.

The {\it namcouple} is a text file with the following characteristics:

\begin{itemize}
\item the keywords used to separate the information can appear in any
  order;
\item the number of blanks between two character strings is
  non-significant;
\item all lines beginning with \# are ignored and considered as
  comments.
\item {\bf blank lines are not allowed.}
\end{itemize}

The first part of {\it namcouple } is devoted to configuration of
general parameters such as the number of models involved in the
simulation or the number of fields.  The second part gathers specific
information on each coupling (or I/O) field, e.g. their coupling
period, the list of transformations or interpolations to be performed
by OASIS3-MCT and associated configuring lines (described in more
details in chapter \ref{sec_transformations}), etc.

In OASIS3-MCT, several {\it namcouple} inputs have been deprecated
but, for backwards compatibility, they are still allowed.  These
inputs will be noted in the following text using the notation
``UNUSED'' and not fully described. Information below these keywords
is obsolete in OASIS3-MCT; it will not be read and will not be used.

In the next sections, a simple {\it namcouple} example is given and
all configuring parameters are described. The additional lines
containing the different parameters required for each transformation
are described in section \ref{sec_transformations}. A realistic {\it
  namcouple} can be found in {\tt
  oasis3-mct/examples/tutorial/data\_oasis3/} directory.

\section{An example of a simple {\it namcouple}}
\label{subsec_examplenamcouple}

The following simple {\it namcouple} configures a run into which an
ocean, an atmosphere and an atmospheric chemistry models are
coupled. The ocean provides only the SOSSTSST field to the atmosphere,
which in return provides the field CONSFTOT to the ocean. One field
(COSENHFL) is exchanged from the atmosphere to the atmospheric
chemistry, and one field (SOALBEDO) is read from a file by the ocean.

\begin{verbatim}
######################################################################
# First section
#
 $SEQMODE
#
 $CHANNEL
#
 $NFIELDS
    4  
#
 $JOBNAME
#
 $NBMODEL
    3  ocemod   atmmod  chemod  55  70   99 
#
 $RUNTIME
    432000
#
 $INIDATE
#
 $MODINFO
#
 $NLOGPRT
   2     1
#
 $CALTYPE
#
######################################################################
# Second section 
 $STRINGS
#
# Field 1
 SOSSTSST SISUTESU 1 86400  5  sstoc.nc  EXPORTED
 182  149  128  64  toce  atmo   LAG=+14400  SEQ=+1
 P 2 P 0
 LOCTRANS CHECKIN MAPPING  BLASNEW CHECKOUT 
#
  AVERAGE 
  INT=1
  map_toce_atmo_120315.nc src opt
  1.0  1
  CONSTANT     273.15 
  INT=1
#
# Field 2
 CONSFTOT SOHEFLDO 6 86400  4   flxat.nc  EXPORTED
 atmo   toce  LAG=+14400  SEQ=+2
 P 0 P 2
 LOCTRANS  CHECKIN  SCRIPR CHECKOUT
#
  ACCUMUL 
  INT=1
  BILINEAR LR SCALAR LATLON 1
  INT=1
#
# Field 3
 COSENHFL  SOSENHFL  37  86400   1  flda3.nc  IGNOUT 
 atmo   atmo LAG=+7200 
 LOCTRANS
 AVERAGE
#
# Field 4
 SOALBEDO SOALBEDO  17  86400  0  SOALBEDO.nc  INPUT
#####################################################################
 $END
\end{verbatim}

% section{An example of a simple {\it namcouple}}

\section{ First section of {\it namcouple} file}
\label{subsec_namcouplefirst}

The first section of {\it namcouple } uses some predefined keywords
prefixed by the \$ sign to locate the related information. The \$ sign
must be in the second column. The first ten keywords are described
hereafter:

\begin{itemize}

\item {\tt \$SEQMODE}: UNUSED

\item {\tt \$CHANNEL}: UNUSED

\item {\tt \$NFIELDS}: On the line below this keyword is the total
  number of field entries in the second part of the {\it
    namcouple}. If more than one field are described on the same line
  (new in OASIS3-MCT\_1.0, see appendix \ref{sec_changes_new}) this
  counts as only one entry.

\item {\tt \$JOBNAME}: UNUSED

\item {\tt \$NBMODEL}: On the line below this keyword is the number of
  models running in the given experiment followed by {\tt
    CHARACTER$\star$6} variables giving their names, which must
  correspond to the name announced by each model when calling {\tt
    oasis\_init\_comp} (second argument, see section
  \ref{subsubsec_Initialisation}).

  Then the user may indicate on the same line the maximum Fortran unit
  number used by the models. In the example, Fortran units above 55,
  70, and 99 are free for respectively the ocean, atmosphere, and
  atmospheric chemistry models. {\bf In all cases, OASIS3-MCT library
    assumes, during the initialization phase, that units 1025 and 1026
    are free and temporarily uses these units to read the {\it
      namcouple} and to write corresponding log messages to file {\tt
      nout.000000}.} After the initialization phase, OASIS3-MCT will
  still suppose that units above 1024 are free, unless maximum unit
  numbers are indicated here in the {\it namcouple}.
  % If {\tt \$CHANNEL} is {\tt NONE}, {\tt \$NBMODEL} has to be 0 and
  % there should be no model name and no unit number.

\item {\tt \$RUNTIME}: On the line below this keyword is the total
  simulated time of the run, expressed in seconds (or any other time
  units as long as the same are used in all models and in the {\it
    namcouple}, see \ref{subsubsec_sendingreceiving}).
  % If {\tt \$CHANNEL} is {\tt NONE}, {\tt \$RUNTIME} has to be the
  % number of time occurrences of the field to interpolate from the
  % restart file.

\item {\tt \$INIDATE}: UNUSED

\item {\tt \$MODINFO}: UNUSED
 
\item {\tt \$NLOGPRT}: The first and second numbers on the line below
  this keyword refer to the amount of debug and time statistic
  information written by OASIS3-MCT for each model and processor.

  The first number (that can be changed at runtime with the {\tt
    oasis\_set\_debug} routine, see section
  \ref{subsubsec_auxroutines}) may be:
  \begin{itemize}
  \item 0 : one file debug.root.xx is open by the master proces of
    each model and one file debug\_notroot.xx is open for all the
    other processes of each model to write only error information.
  \item 1 : one file debug.root.xx is open by the master proces of
    each model to write information equivalent to level 10 (see
    below); one file debug\_notroot.xx is open for all the other
    processes of each model to write error information.
  \item 2 : one file debug.xx.xxxxxx is open by each process of each
    model to write normal production diagnostics
  \item 5 : as for 2 with in addition some initial debug info
  \item 10: as for 5 with in addition the routine calling tree
  \item 12: as for 10 with in addition some routine calling notes
  \item 15: as for 12 with even more debug diagnostics
  \item 20: as for 15 with in addition some extra runtime analysis
  \item 30: full debug information
  \end{itemize}
  The second number defines how time statistics are written out to
  file {\tt *.timers\_xxxx}; it can be:
  \begin{itemize}
  \item 0 : nothing is calculated, nothing is written.
  \item 1 : some time statistics are calculated and written in a
    single file by the processor 0 as well as the min and the max
    times over all the processors.
  \item 2 : some time statistics are calculated and each processor
    writes its own file ; processor 0 also writes the min and the max
    times over all the processors in its file.
  \item 3 : some time statistics are calculated and each processor
    writes its own file ; processor 0 also writes in its file the min
    and the max times over all processors and also writes in its file
    all the results for each processor.
  \end{itemize}
  For more information on the time statistics written out, see section
  \ref{timestat}.

\item {\tt \$CALTYPE}: UNUSED

\end{itemize}

% {Description of {\it namcouple} first section}

\section{Second section of {\it namcouple} file }
\label{subsec_namcouplesecond}

The second part of the {\it namcouple}, starting after the keyword
{\tt \$STRINGS}, contains coupling information for each coupling (or
I/O) field.  Its format depends on the field status given by the last
entry on the field first line ({\tt EXPORTED}, {\tt IGNOUT} or {\tt
  INPUT} in the example above). The field may be :

\begin{itemize}
\item {\tt AUXILARY}: UNUSED
\item {\tt EXPORTED}: exchanged between component models and
  transformed by OASIS3-MCT
\item {\tt EXPOUT}: exchanged, transformed and also written to two
  debug NetCDF files, one before the sending action in the source
  model below the {\tt oasis\_put} call (after local transformations
  {\tt LOCTRANS} and {\tt BLASOLD} if present), and one after the
  receiving action in the target model below the {\tt oasis\_get} call
  (after all transformations). {\tt EXPOUT} should be used when
  debugging the coupled model only. The name of the debug NetCDF file
  (one per field) is automatically defined based on the field and
  component model names.
\item {\tt IGNORED}: with OASIS3-MCT, this setting is equivalent to
  and converted to EXPORTED
\item {\tt IGNOUT}: with OASIS3-MCT, this setting is equivalent to and
  converted to EXPOUT
\item {\tt INPUT}: read in from the input file by the target model
  below the {\tt oasis\_get} call at
  appropriate times corresponding to the input period indicated by the
  user in the {\it namcouple}. See section \ref{subsec_inputdata} for
  the format of the input file.
\item {\tt OUTPUT}: written out to an output debug NetCDF file by the
  source model below the {\tt oasis\_put} call, after local
  transformations {\tt LOCTRANS} and {\tt BLASOLD}, at appropriate
  times corresponding to the output period indicated by the user in
  the {\it namcouple}.

\end{itemize}

\subsection{Second section of {\it namcouple} for {\tt EXPORTED} and
  {\tt EXPOUT} fields}
\label{subsubsec_secondEXPORTED}

The first 3 lines for fields with status {\tt EXPORTED} and {\tt
  EXPOUT} are as follows:
  \begin{verbatim}
   SOSSTSST SISUTESU 1 86400  5  sstoc.nc  EXPORTED
   182  149    128  64  toce  atmo   LAG=+14400 SEQ=+1
   P 2 P 0 
\end{verbatim}
%\vspace{-0.2cm} 
where the different entries are:
\begin{itemize}
\item Field first line:
  \begin{itemize}
  \item {\tt SOSSTSST} : symbolic name for the field in the source
    model ({\tt CHARACTER*128}). It has to match the argument {\tt name}
    of the corresponding field declaration in the source model; see
    {\tt oasis\_def\_var} in section \ref{subsubsec_Declaration}
  \item {\tt SISUTESU} : symbolic name for the field in the target
    model ({\tt CHARACTER*128}).  It has to match the argument {\tt
      name} of the corresponding field declaration in the target
    model; see {\tt oasis\_def\_var} in section
    \ref{subsubsec_Declaration}
  \item 1 : UNUSED but still required for parsing
  \item 86400 : coupling and/or I/O period for the field, in seconds
  \item 5 : number of transformations to be performed by OASIS3 on
    this field
  \item sstoc.nc : name of the coupling restart file for the field
    ({\tt CHARACTER*8}); mandatory even if no coupling restart file is
    effectively used (for more detail, see section
    \ref{subsec_restartdata})
  \item {\tt EXPORTED} : field status
  \end{itemize}
\item Field second line:
  \begin{itemize}
  \item 182 : number of points for the source grid first dimension
    (optional)
  \item 149 : number of points for the source grid second dimension
    (optional)\footnote{For 1D field, put {\tt 1} as the second dimension}
  \item 128 : number of points for the target grid first dimension
    (optional)
  \item 64 : number of points for the target grid second dimension
    (optional)$^{1}$

    {\bf These source and target grid dimensions are optional but note that
    in order to have 2D fields written as 2D arrays in the debug
    files, these dimensions must be provided in the {\it namcouple};
    otherwise, the fields will be written out as 1D arrays.}
  
  \item toce : prefix of the source grid name in grid data files (see
    section \ref{subsec_griddata}) ({\tt CHARACTER*4})
  \item atmo : prefix of the target grid name in grid data files ({\tt
      CHARACTER*4})
  \item {\tt LAG=+14400}: optional lag index for the field (see section \ref{subsub_lag})
  \item {\tt SEQ=+1}: optional sequence index for the field (see
    section \ref{subsec_sec})
  \end{itemize}
\item Field third line
  \begin{itemize}
  \item P : source grid first dimension characteristic (`P':
    periodical; `R': regional).
  \item 2 : source grid first dimension number of overlapping grid
    points.
  \item P : target grid first dimension characteristic (`P':
    periodical; `R': regional).
  \item 0 : target grid first dimension number of overlapping grid
    points.
  \end{itemize}
     
\end{itemize}
    
The fourth line gives the list of transformations to be performed for
this field. In addition, there is one or more configuring lines
describing some parameters for each transformation. These additional
lines are described in more details in the chapter
\ref{sec_transformations}.

\subsection{Second section of {\it namcouple} for {\tt OUTPUT} fields}
\label{subsubsec_secondOUTPUT}
The first 2 lines for fields with status {\tt OUTPUT} are as follows:
  \begin{verbatim}
  COSHFTOT  COSHFTOT   7   86400  0  fldhftot.nc OUTPUT 
  atmo   atmo 
\end{verbatim}
% \vspace{-0.2cm}
where the different entries are as for {\tt EXPOUT} fields, except
that:
\begin{itemize}
\item the source symbolic name must be repeated twice on the field
  first line,
\item the restart file name (here {\tt fldhftot.nc}) is needed only if
  a {\tt LOCTRANS} transformation is present,
\item there is no output file name on the first line,
\item there is no grid dimension\footnote{This means that all output
    fields will be written out in the output files as 1D arrays (this
    should be fixed in the next OASIS3-MCT version).} and no LAG or SEQ
  index on the second line; ;
\end{itemize}
The name of the output file is automatically defined based on the
field and component model names.

The third line is {\tt LOCTRANS} if this transformation is chosen for
the field. Note that {\tt LOCTRANS} is the only transformation
supported for {\tt OUTPUT} fields.

\subsection{Second section of {\it namcouple} for {\tt INPUT} fields}
\label{subsubsec_secondINPUT}

The first and only line for fields with status {\tt INPUT} is:

  \begin{verbatim}
  SOALBEDO SOALBEDO  17  86400  0  SOALBEDO.nc  INPUT
  \end{verbatim}
\vspace{-0.5cm}
where the different entries are:
\begin{itemize}
\item {\tt SOALBEDO}: symbolic name for the field in the target model
  ({\tt CHARACTER*128} repeated twice)
\item 17: index in auxiliary file cf\_name\_table.txt (see above for
  EXPORTED fields)
\item 86400: input period in seconds
\item 0: number of transformations (always 0 for {\tt INPUT} fields)
\item {\tt SOALBEDO.nc}: {\tt CHARACTER*32} giving the input file name
  (for more detail on its format, see section \ref{subsec_inputdata})
\item {\tt INPUT}: field status.
\end{itemize}