prism_def_grid

prism_def_grid(grid_id, grid_name, comp_id, valid_shape, grid_type,ierror)

Table 5.7: prism_def_grid arguments

This routine declares a grid and describes its structure.

• grid_name

  The argument grid_name must match the attribute `local_name' of the corresponding element `grid' in the SMIOC XML file and must be unique within the component.

• valid_shape

  The array valid_shape is dimensioned (2,ndim) and gives, for each of the ndim dimensions of the grid (see table 5.8), the minimum and maximum local index values corresponding to the ``valid'' part of the corner (see 5.3.2), point (see 5.3.6, mask (see 5.3.3) and field (see 5.4.1) arrays treated by the process, without the halo region (i.e. $iloc_{low}, iloc_{high}, jloc_{low}, jloc_{high}$ on figure 5.7). For example, if the actual extent of the first dimension is from 1 to 100, it may be that the ``valid'' part of the array goes from 2 to 98 (i.e. valid_shape(1,1)=2 and valid_shape(2,1)=98 . Note that the ``valid'' part of the grid must be uniquely defined and cannot overlap to itself.

  
  
  

  Figure 5.1: 2D example of the valid shape (expressed as valid_shape in prism_def_grid) of the corner, point, mask and field arrays transfered through the PSMILe API with shape corner_actual_shape or point_actual_shape or mask_actual_shape or var_actual_shape respectively (see below).

  

• grid_type

  The argument grid_type describes the grid type and implicitly specifies the shape of the corner, point, mask and field arrays passed to the PSMILe. Grids that are currently supported cover:

  • in the horizontal: regular, irregular, Gaussian reduced
  • in the vertical: regular
  • non-geographical grids (`gridless' grids) are also supported for repartitioning (but not for I/O in the current version).
  Table 5.8 lists the possible values of grid_type for the different grids supported by OASIS4 and the corresponding number of dimensions ndim.

  Other characteristics of the grid will be described by other routines and the link will be made by the grid identifier grid_id.

  
  
  
  

  Table 5.8: Possible values of grid_type and ndim for the different grids supported by PSMILe.

  
  
  

Gaussian reduced grids. For Gaussian reduced grids, all processes defining the grid have to call
prism_def_grid with grid_type=PRISM_gaussreduced_regvrt. Two numerical dimensions (ndim=2) are used to describe the 3D domain: the first dimension covers the horizontal plane and the second dimension covers the vertical. Furthermore, all these processes have to provide a description of the global reduced gaussian grid by a call to prism_reducedgrid_map (see 5.3.5), and have to describe the local partition of the grid with a call to prism_def_partition (see 5.3.4).

Non-geographical grids. For fields located on a non-geographical grid, prism_def_grid still has to be called with grid_type = PRISM_gridless. For coding reasons, ndim must be always equal to 3 and the call to prism_def_grid must be done with valid_shape(1:2, 2:3) = 1. The partitioning of non-geographical grids must also be described by a call to prism_def_partition (see 5.3.4); furthermore, a call to prism_set_points_gridless (see 5.3.7) is also required.