Couplers allow the data exchange – e.g. of energy, momentum, water and important trace gases such as carbon dioxide – between the Earth system model components for ocean, atmosphere and land, and are essential for representing the climate system's complex processes and feedbacks in the models.

To meet the special needs of the Icosahedral Nonhydrostatic general circulation model (ICON), Moritz Hanke, Dr René Redler, Teresa Holfeld and Maxim Yastremsky wrote "Yet Another Coupler" (YAC).

In different climate models, scientists usually use different grids for their calculations. Traditionally, rectilinear grids have mostly been used, and the bases of the grid cells were rectangular. Today, unstructured grids with triangles or other polygonal shapes are used as well. The new coupler supports multiple grid types, as for example the unstructured grid used by ICON. YAC offers flexible coupling of physical fields defined on different types of grids on the sphere. All supported grids can be combined with any of the interpolations supported.

The software version YAC 1.2.0 is available to the climate modelling community. Information about access to the software is provided on the YAC Doxygen website under section code availability: https://doc.redmine.dkrz.de/YAC/html/index.html