prism_set_corners

prism_set_corners (grid_id, nc, corner_actual_shape, corner_1st_array,
corner_2nd_array, corner_3rd_array, ierror)

Table 5.9: prism_set_corners arguments

For geographical grids, the volume elements which discretise the computing domain covered locally by the process are defined by giving the geographical position of the corner (vertices) of those volume elements. The exchange and repartitioning between two coupled components of a field provided on a geographical grid will be based on this geographical description of the local partition.

• corner_actual_shape

  The array corner_actual_shape is dimensioned (2,ndim) and gives, for each of the ndim dimensions (see table 5.8), the minimum and maximum local index values corresponding to the ``actual'' shapes of the corner_xxx_array arrays treated by the process including halo regions. corner_actual_shape is therefore greater or equal to the valid_shape (see section 5.3.1).

• corner_xxx_array

  Shape of corner_xxx_shape

  Table 5.10 gives the expected shape of the corner_xxx_array for the various grid_type. For PRISM_irrlonlat_regvrt, the corners must be given in an order such that when moving from one corner to the next one, the grid cell interior must always be to the left¹⁰. Furthermore, the first corner must be the lower left one in the (i,j) space, as illustrated in Figure 5.2 in the case nc$_{half} = 4$.

  
  
  
  

  Table 5.10: Dimensions of corner_xxx_arrays for the various grid_type; nc is the total number of corners for each volume element; nc$_{half}$ is nc divided by 2; i, j, k, npt_hor are the extent of the respective numerical dimensions (see table 5.8).

  
  
  

  
  
  

  Figure 5.2: Corner ordering for PRISM_irrlonlat_regvrt grids (here with nc$_{half} = 4$)

  

  Units of corner_xxx_array

  Currently, the array corner_1st_array must be provided in degrees East in the interval -7*180 to 7*180; longitudes of the corners of one cell have to define the size of the cell (e.g. a cell with corners at 5 and 355 is a cell of 350 degrees, not a cell of 10 degrees). Currently, the array corner_2nd_array must be provided in degrees North (spherical coordinate system) in the interval -90 to 90. For corner_3rd_array, units must be the same on the source and target sides.

Footnotes

... left¹⁰

This means that the corners must be given in a mathematical positive sense for a right-handed (i,j,k) coordinate system, but in a mathematical negative sense for a left-handed (i,j,k) coordinate system. See also http://en.wikipedia.org/wiki/Cartesian_coordinate_system.