Sensitivity of Tropical Wave Structure to Resolution and Convection Treatment in a Global Non-Hydrostatic Model

Abstract

Tropical waves shape weather across equatorial regions, yet their representation in global models remains a formidable challenge. This study investigates how model fidelity depends on two key factors: horizontal resolution (120 km to 3.75 km) and the treatment of convection (parameterized vs. explicit). The 3.75-km simulation with explicit convection most faithfully reproduces wave structures and wave-driven rainfall. Interestingly, a 15-km simulation with an alternative parameterization scheme achieves comparable structural fidelity and wave-driven rainfall, but at the cost of a pronounced overall precipitation bias. Moreover, simulations that excel at capturing wave structure tend to perform poorly in reproducing propagation speed, whereas parameterized simulations—though less realistic in structure and rainfall—represent speed more accurately. This trade-off highlights both the promise and the limitations of global kilometer-scale models and underscores the need for continued model development to advance tropical weather and climate prediction.