Next-Generation Model Development Group

Figure: Cubic grid(left top) and icosahedral grid(left bottom). Right figure shows the result of life-cycle experiment of extratropical cyclones by the icosahedral atmospheric model with 3.5km grid.

We are developing super-high resolution atmospheric and oceanic general circulation models, which can be run efficiently on the "Earth Simulator". In order to explicitly resolve clouds for the atmosphere, it is necessary to cover the the entire globe with less than 5km mesh. For the ocean, explicit resolving of mesoscale eddies requires less than 10km grid size. For these purposes, we do not employ the traditional latitude-longitude grid. Instead, we use quasi-uniform grid systems, which are advantageous for parallel-computation and calculation of physical processes.

The atmospheric modeling subgroup is developing a global cloud resolving model based on the non-hydrostatic equations by using an icosahedral grid structure as the horizontal mesh. With this model, we can explicitly calculate cloud physical processes including various transformations of water substance such as cloud water, rain, snow, and graupel. By directly resolving clouds and avoiding cumulus parameterizations with our new model, it is hoped that this model will lead to breakthrough of predictions of hydrological cycle and climate change.

The oceanic modeling subgroup is developing an oceanic general circulation model by using the cubic grid. We expect that the mass and heat transport caused by the mesoscale eddies can be studied in the world ocean using this new model without parameterizations. In parallel to this development, we also carry out eddy-resolving calculation of the southern ocean as a first step to the study of the world ocean eddy activities.