Improvement Of A Flux-form Non-hydrostatic Dynamic Core On The Yin-yang Grid

The conservative dynamic core on quasi-uniform grid is essential for global high-resolution numerical weather prediction and long-term climate projection.In this article,a flux-form non-hydrostatic dynamic core is developed on the Yin-Yang grid to improve the limitation of time step and computational efficiency of model.Yin-Yang grid is a quasi-uniform grid and it can implove the performance of latitude-longitude grid.The dynamic core build flux-form equations which uses the predictand with better conservation.A explicit flux-form transport scheme and a finite volume method are also adopted in order to ensure the mass conservation.For vertical direction,height-based terrain-following coordinate and Lorenz grid are used.Three-order Langrangian interplotion is used in model boundary process.As for time integration,the dynamic core uses HEVI scheme for fast wave calculation and the 3^th Runge-kutta scheme for slow wave.The 5^th upwind finite differential scheme is used for horizontal spatial integration and the 2^th differential method for vertical as well.A series of idealized three-dimensional experiments with the horizontal resolution of 2.5°are carried out to test the effect of the new frame.The numerical results reveal strong stability and good accuracy.The error of vertical velocity shows an order about 10^-5 and which of the meridional velocity about 10^-2 in the 12-day balanced flow test.Despite the low resolution of the model,the propagation of the14-day Rossby-Haurwitz wave is stably well simulated without deformation.The mountain-Rossby wave experiment shows that the trough initiated at the lee side of the mountain is developed downstream,and propagated to the southern hemisphere.As the results show,the flux-form non-hydrostatic dynamic core on the Yin-Yang is able to reach a stable and high-precision time integration with good conservative calculation.The dymamic core satisfies the demand for medium-range ensemble prediction and it provides a foundation for later construction of global spherical quasi-uniform dynamic core.