YetAnotherCoupler
2.4.2

The Hybrid cubic spherical BernsteinBézier (short: HCSBB) patch interpolation method is based on Alfeld, P. et al. “BernsteinBézier polynomials on spheres and spherelike surfaces.” Comput. Aided Geom. Des. 13 (1996): 333349.. It is implemented for source fields defined on grid cell or corner points.
The interpolation method first triangulates the source grid. Then the derivatives of the source field across the edges of the triangles are estimated. Using these, triangular patches from a blend of spherical BernsteinBézier polynomials are constructed which are used for the interpolation of the target points.
The resulting target field will always have a contiguous first derivative.
The Patch recovery interpolation method (Zienkiewicz, O. and Zhu, J.: The Superconvergent Patch Recovery and a Posteriori Error Estimates. Part 1: The Recovery Technique, Int. J. Numer. Meth. Eng., 33, 1331–1364, 1992.), which was in included in YAC1 and is implemented in the Earth System Modeling Framework does not guarantee the above mentioned property, which is why we implemented HCSBB in YAC2 as a replacement.
This interpolation method is computationally expensive and produces a quite big interpolation stencil.
HCSBB currently has no option that can be configured by the user.