“…A range of new general circulation models, including the Finite Element Sea Ice-Ocean Model (FESOM) (Wang et al, 2014), the Finite Volume Community Ocean Model (FVCOM) (Chen et al, 2003(Chen et al, , 2007Lai et al, 2010), the Stanford Unstructured Non-hydrostatic Terrain-following Adaptive NavierStokes Simulator (SUNTANS) (Fringer et al, 2006;Vitousek and Fringer, 2014), and the Second-generation Louvainla-Neuve Ice-ocean Model (SLIM) (Bernard et al, 2007;Comblen et al, 2009), are based on semi-structured triangular grids, with the horizontal directions discretised according to an unstructured spherical triangulation, and the ver-D. Engwirda: Unstructured grid-generation for general circulation modelling 2119 tical direction represented as a stack of locally structured layers. The Model for Predication Across Scales (MPAS) (Skamarock et al, 2012;Ringler et al, 2013Ringler et al, , 2008) adopts a similar arrangement, except that a locally orthogonal unstructured discretisation is adopted, consisting of both a Spherical Voronoi Tessellation (SVT) and its dual Delaunay triangulation.…”