Evaluation of Community Atmosphere Model Version 6 and Its Super-Parameterized Version in Simulation of Cloud and Radiation Using Satellite Observation

Cloud plays a crucial role in modulating the energy budget of the earth-atmosphere system. Cloud-resolving models have been demonstrated to be capable of better simulating the microphysical processes within clouds. This study assesses the super-parameterized version of Community Atmosphere Model Version 6 (SPCAM6) in simulating clouds, radiation, and precipitation. The results indicate that SPCAM6 effectively reduces the overestimation of cloud amount in CAM6, particularly in equatorial and mid-high latitude regions. The improvement in cloud amount simulation further enhances the simulation of cloud radiative forcing and precipitation. Through further research on the North Pacific, Southern Ocean regions and Maritime Continent, it is found that with the coupling of the cloud-resolving model, cloud amount at high, middle, and low levels all exhibits a decreasing trend. However, liquid water content and ice water content (IWC) display different characteristics. Despite a decrease in cloud amount, IWC increases due to the heterogeneity of IWC in sub-grid scales, which is closer to actual observations. SPCAM6 can simulate sub-grid in-cloud processes and capture the in-cloud heterogeneity distribution, showing potential as a tool for understanding sub-grid cloud processes.