Simulating atmospheric dust and its radiative impact with a global variable-resolution model

In this study, a global variable-resolution modeling framework of atmospheric dust and its radiative feedback is introduced and evaluated. In this model, atmospheric dust is simulated simultaneously with the meteorological fields, and dust-radiation interaction is included. Five configurations of global mesh with the refinement at different resolutions and over different regions of interest are used to explore the impacts of regional refinement on modeling dust lifecycle at regional and global scales. The model produces reasonably the overall magnitudes and spatial variabilities of global dust metrics such as surface mass concentration, total deposition, AOD, and radiative forcing compared to observations and previous modeling results. Two global variable-resolution simulations with mesh refinement over major deserts of North Africa (V16km-NA) and East Asia (V16km-EA) simulates less dust emissions and smaller dry deposition rate inside the refined regions due to the weakend near-surface wind speed caused by better resolved topographic complexity at higher resolution. Dust mass loading over North Africa is close to each other between V16km-NA and U120km, while over East Asia, V16km-EA simulates higher dust mass loading. Over the non-refined areas with the same resolution, the difference between global variable-resolution and uniform-resolution experiments also exist, which is partly related to their difference in dynamic time-step and the coefficient for horizontal diffusion. Refinement at convection-permitting resolution around the Tibet Plateau (TP) leads to significantly different dust and precipitation around the TP against coarse resolution, which implies that dust-precipitation interaction over this area deserves further investigation with this  global variable-resolution modeling framework in future.