Targets and Ongoing Activities of the Model Development at FRSGC especially on the Coupled A-O GCM
Taroh Matsuno
Frontier Research System for Global Change (FRSGC)
Tokyo, Japan
At the FRSGC development of new climate models is directed toward the following three targets:
1. Coupled A-O GCM consisting of a T213 spectral AGCM and an around 0.1° resolution OGCM.
2. Non-hydrostatic global AGCM with the horizontal resolution of ca. 5 km which can express meso-scale convective systems explicitly.
3. Integrated model of various component models of global environment such as atmospheric composition, carbon cycle and ecosystem which are to be developed in other research programs of the FRSGC.
All these targets were determied by considering that newly developed models will be run on the Earth Simulator by exploiting its gigantic resources.
At present activities are limited to the targets 1 and 2 and that toward the latter will be reported later by Sato.
A coupled model is being developed collaborating with the Center for Climate System Research (CCSR) of the University of Tokyo and the National Institute for Environmental Studies (NIES). The atmospheric component is originally developed by CCSR and NIES as the one with T42/L20 resolution and a higher resolution version (T213/L50) is now being developed. It is expected that with this resolution (about 60 km grid) regional climate can be reproduced as well as smaller - scales important weather systems such as Baiu front and typhoons. The original model contains also a new land surface model which includes processes to express variety of surface conditions such as forest, grassland, permafrost and so on. The ocean component is based on the Modular Ocean Model 3 (MOM3) developed at the Geophysical Fluid Dynamics Laboratory. For applying the model to high resolution situation, the polar axis of the spatial coordinate is rotated in such a way that the new poles are located over land and farthest from coastal line, in order to avoid contraction of longitudinal grid separation near the poles. By making the horizontal mesh size around 0.1°, ocean baroclinic eddies can be resolved and the eddy-induced mass transport effect is expected to be included automatically without parameterizing it as proposed by Gent and McWilliams. This is one of major features of our CGCM which can be realized only by using large computer resources.
