OASIS4 offers interpolations and regriddings based on
the Los Alamos National Laboratory SCRIP 1.4
library6. For more
details on these algorithms, see SCRIP 1.4 documentation in
Jones (1999) or
oasis4/doc/SCRIPusers.pdf.
These interpolations and related options are described here in
more detail. All related XML elements and attributes used in the
SMIOC configuration files and mentionned here are precisely defined
in section 6.5.6 and in their corresponding
schema in oasis4/util/xmlfiles.
With OASIS4, all coupling fields must be provided on a 3D grid. If a coupling field is in fact given on a 2D surface (e.g. the SST at the ocean surface) the vertical dimension of the field and the grid must have an extent of 1 (see more details in section 5.3). Therefore, the interpolation of a coupling field must always be expressed either as a full 3D interpolation (see element interp3D) or as a combination of same 2D interpolation for all vertical levels (see element interp2D) followed by a 1D interpolation in the vertical (see element interp1D).
Currently, the 3D interpolation algorithms available are 3D nearest neighbour (element nneighbour3D) or trilinear (element trilinear). A remapping using a set of weights and addresses pre-defined by the user and stored in a file can also be chosen with element user3D (see 4.3.3). The 2D interpolation available are 2D nearest neighbour (element nneighbour2D) or bilinear (element bilinear) or bicubic (element bicubic) or 2D conservative remapping (element conservativ2D). For the interpolation in the vertical, a linear (element linear) algorithm or no interpolation at all (element none), which should be chosen when the extent of the grid is 1 in the vertical, are possible choices.
When the interpolation is expressed as a 2D interpolation for all vertical levels followed by a 1D interpolation in the vertical, the combinations that can be specified are: