Grid data files

The grids of the models being coupled can be given by the user or directly by the model through PSMILe specific calls (see section 4.2) in grid data files. These files can be all binary or all NetCDF. In
/prism/data/toyclim/input_toyclim_standard_standard_prism_2-2.tar.gz, NetCDF examples can be found.

The arrays containing the grid information are dimensioned (nx, ny), where nx and ny are the grid first and second dimension, except for Unstructured (U) and Reduced (D) grid, for which the arrays are dimensioned (nbr_pts,1), where nbr_pts is the total number of grid points.

1. grids or grids.nc: contains the component model grid longitudes, latitudes, and local angles (if any) in single or double precision REAL arrays (depending on OASIS3 compilation options). The array names must be composed of a prefix (4 characters), given by the user in the namcouple on the second line of each field (see section 5.3), and of a suffix (4 characters); this suffix is ``.lon'' or ``.lat'' for respectively the grid point longitudes or latitudes (see /prism/src/mod/oasis3/src
   /mod_label.F90.)

   If the SCRIPR/CONSERV interpolation is used for a grid, the grid data file may contain longitudes and latitudes for model mesh corners as arrays dimensioned (nx, ny, 4) or (nbr_pts,1, 4) where 4 is the number of corners; in this case, it must necessarily be a NetCDF file ( grids.nc). For Logically Rectangular LR grids, the grid corners will be automatically calculated approximately if they are not given in grids.nc. The names of the arrays must be composed of the grid prefix and the suffix ``.clo'' or ``.cla'' for respectively the grid corner longitudes or latitudes.

   If vector fields are defined on a grid which has a local coordinate system not oriented in the usual zonal and meridional directions, the local angle of the grid coordinate system must be given in grids.nc file in an array which name must be composed of the grid prefix and the suffix ``.ang''. The angle is defined as the angle between the first component and the zonal direction (which is also the angle between the second component and the meridional direction). In the grid file in /prism/data/toyclim/input_toyclim_standard_standard_prism_2-2.tar.gz, the angles of the torc grid are given in array torc.ang. If one of the SCRIPR interpolations is requested for a vector field, OASIS3 automatically performs the rotation from the local coordinate system to the geographic spherical coordinate system for a source grid, or vice-versa for a target grid.

   File grids or grids.nc must be present with at least the grid point longitudes and latitudes for all component model.

2. masks or masks.nc: contains the masks for all component model grids in INTEGER arrays (0 -not masked- or 1 -masked- for each grid point). The array names must be composed of the grid prefix and the suffix ``.msk''. This file, masks or masks.nc, is mandatory.

3. areas or areas.nc: this file contains mesh surfaces for the component model grids in single or double precision REAL arrays (depending on OASIS3 compilation options). The array names must be composed of the grid prefix and the suffix ``.srf''. The surfaces may be given in any units but they must be all the same (in INTERP/GAUSSIAN, it is assumed that the units are but they are used for statistics calculations only.) This file areas or areas.nc is mandatory for CHECKIN, CHECKOUT or CONSERV, and used for statistic calculations in INTERP/GAUSSIAN; it is not required otherwise.

4. maskr or maskr.nc: this file contains Reduced (D) grid mask in INTEGER arrays dimensioned array(nbr_pts) where nbr_pts is the total number of the Reduced grid points (0 -not masked- or 1 -masked- for each grid point). This file is required only for grids to which the REDGLO or GLORED transformation is applied. As mentionned above, these transformations should not be used anymore as interpolations are now available for Reduced grids directly. If used, the mask array name must be ``MSKRDxxx'' where ``xxx'' is half the number of latitude circles of the reduced grid (032 for a T42 for example).

If the binary format is used, grids, masks, areas, and maskr must have the following structure. The array name is first written to the file to locate a data set corresponding to a given grid. The data set is then written sequentially after its name. Let us call ``brick'' the name and its associated data set. The order in which the bricks are written doesn't matter. All the bricks are written in the grid data file in the following way:

        ...
        WRITE(LU) array_name
        WRITE(LU) auxildata
        ...

• LU is the associated unit,
• array_name is the name of the array (CHARACTER*8),
• auxildata is the REAL or INTEGER array dimensioned (nx, ny) or (nbr_pts,1) containing the grid data.