Resolution Dependence in a Global Atmospheric Simulation From km to 220 m Grid Spacing

Abstract We conducted a 220‐m mesh simulation over the global domain with realistic topography. This can be called a first “global large‐eddy simulation” (GLES) for deep convection. The resolution dependence across km‐ to sub‐km scales and sensitivity to turbulence schemes are investigated. The results showed that the too‐intense localized precipitation frequently produced in km‐scale models, known as “popcorn‐like” precipitation, weakens as resolution increases. Although zonal mean precipitation differs substantially across turbulence schemes at km‐scale resolution, it decreases as resolution increases, indicating convergence across the schemes. Low cloud fraction decreases with increasing resolution, whereas the resolution dependence of high cloud fraction depends on the turbulence scheme: it increases for the Smagorinsky‐type scheme and decreases for the Mellor‐Yamada‐type schemes. The response of low cloud distribution differs between the turbulence schemes. The present results indicate that GLES is promising for simulating precipitation intensity, while cloud simulation remains uncertain.