Significant Imprints of Vertical Resolution on Scale Interactions in the Global Model for Prediction Across Scales

Global kilometer-scale model simulations have demonstrated clear benefits from refining horizontal resolution in representing mesoscale weather phenomena, yet the role of vertical resolution remains comparatively underexplored. To address this gap, 40-day experiments with the model for prediction across scales systematically varied both horizontal and vertical grid spacing. Horizontal refinement had minimal impact on kinetic energy (KE) at mesoscale wavelengths, whereas refinements in vertical resolution led to intensified KE transfer between the mesoscales and synoptic scales. This enhanced coupling was spatially connected to Rossby wave-like features. The results show that vertical resolution impinges on the mesoscale KE spectrum, substantially influencing the kinematics of the mid-latitude upper-troposphere, and underscoring the importance of carefully prescribing vertical grid spacing in high-resolution global models.