Dynamical Core of an Atmospheric General Circulation Model on a Yin–Yang Grid

The three-dimensional dynamical core of an atmospheric general circulation model employing Yin–Yang grid is developed and examined. Benchmark test cases based on the shallow-water model configuration are first performed to examine the validity of two-dimensional calculations. The experiments show that the model simulates reasonable flow fields with second-order accuracy. The model validation is then extended to three-dimensional features where the capability of the dynamical core on the Yin–Yang grid has not been tested before: the global mountain gravity wave, long-term integration, and life cycle experiments. The simulated flow fields are in good agreement with the results of original experiments in all three experiments. The sensitivity of the model flow field to the overset region is also tested. The experiments reveal that the presence of the overset region does not significantly affect the dynamics on both long and short time scales, if the number of overset grids is fixed to three and the high-order interpolation method is applied for data interpolation between the Yin–Yang grids.