Effect of horizontal and vertical resolution in a non-hydrostatic global model: An aquaplanet study

The effect of the spatial resolution of numerical models on the atmospheric circulation has been a concern for some decades. In particular, the performance of physical processes in a global model is significantly affected by vertical resolution because processes in the most models are vertically one dimensional models. Nevertheless, systematic studies of how simulations are affected by finer vertical spacing have been limited, while many research groups have devoted to studies on horizontal resolution dependency. This study presents preliminary results related to the issue of how the simulation of overall large-scale features and precipitation by a non-hydrostatic global model depends on horizontal and vertical resolution. As a tool, a Non-hydrostatic Icosahedral Model (NIM), which has been developing at National Oceanic and Atmospheric Administration Earth System Research Laboratory (NOAA ESRL), is used. Aquaplanet simulations, forced by idealized zonally symmetric sea surface temperature (SST), are performed with systematically increasing resolutions. Verification of NIM aqua-planet simulation at low resolution with other published results, and the simulated results obtained from different resolution will be compared along with the discussion on the basic dependence of each physical process on horizontal and vertical model resolution.