1 Second section of namcouple for EXPORTED and EXPOUT fields

The first 3 lines for fields with status EXPORTED and EXPOUT are as follows:

   SOSSTSST SISUTESU 1 86400  5  sstoc.nc  EXPOUT
   182  149    128  64  toce  atmo   LAG=+14400 SEQ=+1
   P 2 P 0

where the different entries are:

• Field first line:
  • SOSSTSST : symbolic name for the field in the source component (80 characters maximum). It has to match the argument name of the corresponding field declaration in the source component; see oasis_def_var in section 2.2.5
  • SISUTESU : symbolic name for the field in the target component (80 characters maximum). It has to match the argument name of the corresponding field declaration in the target component; see oasis_def_var in section 2.2.5
  • 1 : UNUSED but still required for parsing
  • 86400 : coupling and/or I/O period for the field, in seconds
  • 5 : number of transformations to be performed by OASIS3 on this field
  • sstoc.nc : name of the coupling restart file for the field (32 characters maximum); mandatory even if no coupling restart file is effectively used (for more detail, see section 5.2)
  • EXPOUT : field status
• Field second line:
  • 182 : number of points for the source grid first dimension (optional)
  • 149 : number of points for the source grid second dimension (optional)⁸
  • 128 : number of points for the target grid first dimension (optional)
  • 64 : number of points for the target grid second dimension (optional)$^{1}$

    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 namcouple; otherwise, the fields will be written out as 1D arrays.

  • toce : prefix of the source grid name in grid data files (see section 5.1) (80 characters maximum)
  • atmo : prefix of the target grid name in grid data files (80 characters maximum)
  • LAG=+14400: optional lag index for the field (see section 2.5.3)
  • SEQ=+1: optional sequence index for the field (see section 2.5.4)
• Field third line
  • P : source grid first dimension characteristic (`P': periodical; `R': regional).
  • 2 : source grid first dimension number of overlapping grid points.
  • P : target grid first dimension characteristic (`P': periodical; `R': regional).
  • 0 : target grid first dimension number of overlapping grid points.

• 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 4.

Support to couple multiple fields via a single communication

With OASIS3-MCT, it is possible to couple mutiple fields via a single communication. To activate this option, the user must list the related fields on a single entry line (with a maximum of 5000 characters on one line) through a colon delimited list in the namcouple, for example:

ATMTAUX:ATMTAUY:ATMHFLUX TAUX:TAUY:HEATFLUX 1 3600 3 rstrt.nc EXPORTED

All fields will then use the same namcouple settings (source and target grids, transformations, etc.) for that entry. In the component model codes, these fields are still apparently sent or received one at a time through individual oasis_put and oasis_get. Inside OASIS3-MCT, the fields are stored and a single mapping and send or receive instruction is executed for all fields. This is useful in cases where multiple fields have the same coupling transformations and to reduce communication costs by aggregating multiple fields into a single communication.

This option does not put any constraint on the order of the related oasis_put and oasis_get in the codes.

As they appear in one single entry line, these fields must share the same coupling restart file but this restart file may contain other fields.

Footnotes

... (optional)⁸

For 1D field, put 1 as the second dimension