Resolution Dependencies of Deep Moist Convections in the Sub-kilometer Global Simulation

Abstract:

Sub-kilometer global simulation opens the door for resolving the cloud and examining the deep moist convection characteristics over the globe. Miyamoto et al. (2013) found the global-mean convection characteristics are drastically changed around 2 km grid spacing through a series of grid-refinement resolution testing (14 km - 0.8 km) with a constant vertical resolution by using NICAM (Satoh et al., 2014). We have implemented the comprehensive analysis of these simulations and discuss the diversity of convection characteristics. Less difference is found in the essential change of the simulated convection characteristics around 2 km grid spacing in between Land and Ocean. However, that change is more remarkable over the mid-latitude than tropics. We also categorized the convection based on the cloud disturbance; Madden-Julian oscillation (MJO), tropical cyclones, mid-latitudinal low depressions, and fronts. The convection in MJO has strong upward motion and larger core than other convections. It leads to less change of convection characteristics in MJO around 2 km grid spacing. This would be attributed with the strong thermodynamic background condition; large convective available potential energy and weak convergence. Convection with strong low-level convergence largely contributes the global mean convection features.