What Can We Find By Using The Global Cloud Resolving Model?

Recent advanced computer facility enables us to perform the global cloud resolving simulation. In Frontier Research Center for Global Change ( FRCGC ), we have been developing a new high-resolution global atmospheric model in cooperation with Center of Climate System Research ( CCSR ) in the University of Tokyo. This global model, called NICAM ( Nonhydrostatic ICosahedral Atmospheric Model ), is intended to be run in super high-resolution for the climate research. The first development of NICAM has just completed. The highest horizontal resolution is now 3.5km. Namely, the model can resolve each of cumulus. Such a global cloud resolving approach may avoid the ambiguity of cumulus parameterization. This means that we have a powerful tool for climate study and numerical weather prediction. However, there is a criticism that while the model result becomes realistic and provides much information, the interpretation of the model results becomes complex and we tend to lose the scientific sight. We always must make efforts to take an essence and/or mechanism of phenomena from the model results. Furthermore, we should compare the model results with observational data, especially, satellite data. In this paper, we introduce several results from the global cloud resolving simulation and attempt to compare the model results with observational results. First, we show the aqua planet experiment. In this simulation, we could capture the hierarchy structure of cloud; the super cloud cluster as the convectively coupled Kelvin wave, cloud cluster in the super cluster, meso-scale convective system in the cloud cluster. Second, we show the deterministic run with the realistic topography for the investigation of the predictability of the tropical cloud cluster, tropical cyclones, and so on. From the viewpoints of organization of cloud system, we found that the organization in the tropics is very sensitive to the boundary layer scheme and the vertical profile of water vapor. Third, we show an attempt of climate sensitivity focusing on the cloud feedback between the present climate and global warming climate. Such a simulation by the global cloud resolving model is a challenging study and gives an impact to the climate study community.