3D interpolations and remappings

3D interpolations and remappings in OASIS4 are just 3D extensions of the SCRIP 2D algorithms (see section 4.3.1). These interpolations are implemented but still need to be fully validated.

• 3D nearest neighbour (element nneighbour3D): an inverse-distance weighted nearest-neighbour interpolation (the distance is the square root of the sum of the square radial distance and the square of the great circle distance on the sphere at the highest vertical level):
  • The number N of source neighbours can be specified (element nbr_neighbours).
  • The distance can be weighted by a Gaussian (element gaussian_variance)
  • If some or all of the N nearest neighbours are masked, different options are available (element if_masked)
  • This interpolation is available for all types of 3D grid supported by OASIS4 (see section 5.3.1).

• trilinear (element trilinear): an interpolation based on a local trilinear approximation :
  • If some or all of the 8 bilinear neighbours are masked, different options are available (element if_masked).
  • This interpolation is available for all types of 2D grid supported by OASIS4 (see section 5.3.1).